安原英明（ヤスハラヒデアキ） - インフラ空間情報基盤研究部門 -愛媛大学防災情報研究センタ -　

氏名: 安原英明（ヤスハラヒデアキ）

学位: 京都大学土木工学専攻修士課程

J-Global ID: 201501002234494774

研究キーワード: 透水特性岩盤岩石不連続面鉱物溶解力学クリープ連成現象模擬セメント溶液温度・拘束圧プロパント続成作用不連続面温度液状化対策エアースパージング遠心模型実験岩盤水理 THMC連成放射性廃棄物地層処分熱水貯蔵システムヒマラヤ水系化学反応総合防災放射性廃棄物処分岩盤工学防災教育三軸試験圧力融解岩盤透水性プラクチャー不飽和土

研究分野: 社会基盤（土木・建築・防災） / 地盤工学
エネルギー / 地球資源工学、エネルギー学
社会基盤（土木・建築・防災） / 防災工学

経歴: 2016年04月 - 現在愛媛大学大学院・理工学研究科教授
2007年10月 - 2016年03月愛媛大学大学院・理工学研究科准教授
2005年11月 - 2007年09月愛媛大学大学院・理工学研究科助教
学歴

学歴: 2001年08月 - 2005年10月ペンシルバニア州立大学 Dpt. Energy and Geo-Environmental Engineering
2000年04月 - 2003年03月京都大学大学院・理工学研究科土木工学専攻博士後期課程（中途退学）
1998年04月 - 2000年03月京都大学大学院・工学研究科土木工学専攻修士課程
1994年04月 - 1998年03月京都大学土木工学科

所属学会: 日本材料学会 AMERICAN ROCK MECHANICS ASSOCIATION ダム工学会資源・素材学会岩の力学連合会地盤工学会土木学会

論文: Utilization of Soybean as Catalyst Material in Enzyme-Mediated Calcite Precipitation (EMCP) for Crack Healing Concrete
Regina Aprilia Zulfikar, Heriansyah Putra, Hideaki Yasuhara
Journal of the Civil Engineering Forum 7 1 59 - 70 2021年01月 [査読有り]
研究論文（学術雑誌）
Development of rock fracturing model considering mineral composition and distribution and its application to coupled Thermal-Hydraulic-Mechanical-Chemical (THMC) simulator
Kiyoshi Kishida, Shogo Izawa, Sho Ogata, Hideaki Yasuhara
JGS Special Publication In press 2020年09月 [査読有り]
研究論文（学術雑誌）
Review of Enzyme-Induced Calcite Precipitation as a Ground-Improvement Technique
Heriansyah Putra, Hideaki Yasuhara, Erizal, Sutoyo, Muhammad Fauzan
Infrastructures 5 8 66 - 66 2020年08月 [査読有り]
研究論文（学術雑誌）
Calcite-induced precipitation methods (CIPMs) have recently become potential techniques in geotechnical engineering for improving the shear strength of sandy soil. One of the most promising methods among them is enzyme-induced calcite precipitation (EICP). In this technique, a mixed solution composed of reagents and the urease enzyme, which produces calcite, is utilized as the grouting material. The precipitated calcite in granular soil provides ties among the grains of soil and limits their mobility, thus promoting an improvement in strength and stiffness and also a reduction in the hydraulic conductivity of sandy soil. This paper discusses the potential increase in the strength and stiffness of the soil, the additional materials for grouting, the effect of these materials on the treatment process, and the engineering properties of the soil. The possible sources of the urease enzyme and the applicability of the EICP method to other soil types are also discussed in this paper. The environmental and economic impacts of the application of EICP are also presented. The envisioned plans for application, potential advantages, and limitations of EICP for soil stabilization are discussed. Finally, the primary challenges and opportunities for development in future research are briefly addressed.
Predictions of Rock Temperature Evolution at the Lahendong Geothermal Field by Coupled Numerical Model with Discrete Fracture Model Scheme
Muhammad Qarinur, Sho Ogata, Naoki Kinoshita, Hideaki Yasuhara
Energies 13 12 3282 - 3282 2020年06月 [査読有り]
研究論文（学術雑誌）
The comprehensive exploitation of geothermal fields has an impact on the productivity of the reservoirs. To realize sustainable steam production, changes in the rock temperature need to be predicted and controlled. A coupled thermo-hydro-mechanical (THM) model employing COMSOL Multiphysics was proposed to study the characteristics of heat transfer, fluid flow, and solid deformation at the Lahendong geothermal field, in North Sulawesi, Indonesia. The numerical results were compared with analytical and measured data in order to validate the numerical simulation. Based on the results, the predicted temperatures of the production wells showed significant decrease with the production time. In addition, a reduction in the reservoir temperature leads to lower specific gross electrical power within the production well, which should significantly reduce the sustainability of the power plant.
岩盤工学分野における熱・水・応力・化学連成解析
安原英明
電力土木 407 4 - 9 2020年05月 [招待有り]
研究論文（学術雑誌）
Coupled thermal–hydraulic–mechanical–chemical modeling for permeability evolution of rocks through fracture generation and subsequent sealing
Sho Ogata, Hideaki Yasuhara, Naoki Kinoshita, Kiyoshi Kishida
Computational Geosciences 2020年04月 [査読有り]
研究論文（学術雑誌）
鉱物分布を考慮したき裂発生・進展解析による圧裂引張試験時の花崗岩の破壊挙動評価
伊澤正悟,緒方奨,安原英明,木下尚樹,岸田潔
材料 69 3 236 - 242 2020年03月 [査読有り]
研究論文（学術雑誌）
Examination of calcite precipitation using plant-derived urease enzyme for soil improvement
Heny Sulistiawati Baiq, Hideaki Yasuhara, Naoki Kinoshita, Heriansyah Putra, and Erni Johan
International Journal of GEOMATE 19 231 - 237 2020年 [査読有り]
研究論文（学術雑誌）
Instabilities Susceptibility Assessment of Fractured Rock Masses Using Geographic Information System: Application on the Sector of Mako (South-Eastern Senegal)
Déthié Sarr, Hamath Kebe, Hideaki Yasuhara, Ababacar Fall, Mapathé Ndiaye
International Journal of Geosciences 10 995 - 1007 2019年11月 [査読有り]
研究論文（学術雑誌）
損傷理論を導入した多孔質岩盤における熱・水・応力・化学連成解析
緒方奨, 安原英明, 岸田潔
土木学会論文集C（地圏工学） 75 1 131 - 145 2019年01月 [査読有り]
研究論文（学術雑誌）
Small-strain shear modulus and liquefaction resistance of sand with carbonate precipitation
Minson Simatupang, Mitsu Okamura, Kazuyuki Hayashi, Hideaki Yasuhara
Soil Dynamics and Earthquake Engineering 115 710 - 718 2018年09月 [査読有り]
研究論文（学術雑誌）
Improving Shear Strength Parameters of Sandy Soil using Enzyme-Mediated Calcite Precipitation Technique
Putra, H, Yasuhara, H, Kinoshita, N, Erizal, Sudibyo
Journal of Civil Engineering Science and Application, 20 2 91 - 95 2018年09月 [査読有り]
研究論文（学術雑誌）
Modeling of coupled thermal-hydraulic-mechanical-chemical processes for predicting the evolution in permeability and reactive transport behavior within single rock fractures
Sho Ogata, Hideaki Yasuhara, Naoki Kinoshita, Dae-Sung Cheon, Kiyoshi Kishida
International Journal of Rock Mechanics and Mining Sciences 107 271 - 281 2018年04月 [査読有り]
研究論文（学術雑誌）
圧力融解を考慮した連成モデルへのDual Porosity理論実装と岩盤の長期透水性評価
緒方奨, 安原英明, 岸田潔
材料 67 3 310 - 317 2018年03月 [査読有り]
研究論文（学術雑誌）
We improved our coupled thermo-hydro-mechanical-chemical (THMC) simulator by adopting the dual porosity model to predict the long-term permeability change of the fractured rocks. The model evaluates influence of the geochemical reaction on the evolution of the permeability in fractured rock. Pressure solution that may occur both at grain contacts and the contacting asperities within fractures was incorporated in the model. By using the developed THMC numerical model, long-term prediction of rock permeability under simulated subsurface environments near the radioactive waste repository was conducted. As a result of analysis, the permeability decreased by two orders of magnitude smaller than the initial value due to the pressure solution contacting asperities within fractures in the excavation distributed zone (EDZ). When carrying out radioactive waste disposal, the pressure solution within the fractures may have the effect on minimizing the increasing of the permeability in EDZ area.
炭酸カルシウム結晶析出時の飽和度が改良砂の液状化強度特性に及ぼす影響
林和幸, 岡村未対, 安原英明, SIMATUPANG Minson
土木学会論文集C（地圏工学） 74 2 164 - 176 公益社団法人土木学会 2018年 [査読有り]
研究論文（学術雑誌）
炭酸カルシウム(CaCO3)の結晶をセメント物質とする固化土のせん断強度は，間隙での結晶析出時の飽和度が低いほど高まるとされている．本研究では，CaCO3析出時の飽和度をコントロールし砂の液状化抵抗の改善効率を高める試みを粒径が異なる砂に適用し，砂の粒径によるその改善効率の違いを調べた．実験ではCaCO3含有率を1%以下，その析出時の飽和度を20 ~ 100%の範囲でコントロールした豊浦砂および4号硅砂供試体を非排水繰返し三軸試験に使用した．CaCO3析出には，ウレアーゼの尿素分解作用を活用する方法を採用した．砂粒子表面に析出した結晶の観察とその同定はSEM-EDXで行った．その結果，飽和度をコントロールしたCaCO3析出による液状化抵抗の改善効果は，CaCO3結晶径に対し砂の粒径が相対的に小さいほど高いことが明らかとなった．
Optimum Condition for the Application of Enzyme-Mediated Calcite Precipitation Technique as Soil Improvement Method
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita
International Journal on Advanced Science, Engineering Information Technology 7 6 2145 - 2151 2017年12月 [査読有り]
研究論文（学術雑誌）
Constitutive model for soft rocks considering structural healing and decay structural healing
Mamoru Kikumoto, Vu Pham Quang Nguyen, Hideaki Yasuhara, Kiyoshi Kishida
COMPUTERS AND GEOTECHNICS 91 93 - 103 2017年11月 [査読有り]
研究論文（学術雑誌）
The behavior of soft rock depends on the contact area between mineral particles and the tensile strength of the interparticle cementation, which are usually referred to as structures. We investigated the effects of structural decay and healing on the behavior of soft rock through monotonic and slide-hold-slide triaxial tests under the drained condition with constant effective confining pressure. We developed a constitutive model for soft rocks incorporating structural healing and decay in the context of the extended critical state theory. The model was validated via laboratory tests and captured the behavior of soft rock, including the healing and decay phenomena. (C) 2017 Elsevier Ltd. All rights reserved.
Applicability of Natural Zeolite for NH-Forms Removal in Enzyme-Mediated Calcite Precipitation Technique
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita
Geosciences 7 61 doi:10.3390/geosciences7030061 2017年06月 [査読有り]
研究論文（学術雑誌）
製紙スラッジ焼却灰を利用した低炭素コンクリートの性能評価
木下尚樹, 氏家勲, 河合慶有, 川口隆, 安原英明, 長江俊勝
Journal of MMIJ 133 6 132 - 139 2017年06月 [査読有り]
研究論文（学術雑誌）
Application of magnesium to improve uniform distribution of precipitated minerals in 1-m column specimens
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita, Akira Hirata
GEOMECHANICS AND ENGINEERING 12 5 803 - 813 2017年05月 [査読有り]
研究論文（学術雑誌）
This study discussed the possible optimization of enzyme-mediated calcite precipitation (EMCP) as a soil-improvement technique. Magnesium chloride was added to the injection solution to delay the reaction rate and to improve the homogenous distribution of precipitated minerals within soil sample. Soil specimens were prepared in 1m PVC cylinders and treated with the obtained solutions composed of urease, urea, calcium, and magnesium chloride, and the mineral distribution within the sand specimens was examined. The effects of the precipitated minerals on the mechanical and hydraulic properties were evaluated by unconfined compressive strength (UCS) and permeability tests, respectively. The addition of magnesium was found to be effective in delaying the reaction rate by more than one hour. The uniform distribution of the precipitated minerals within a 1-m sand column was obtained when 0.1 mol/L and 0.4 mol/L of magnesium and calcium, respectively, were injected. The strength increased gradually as the mineral content was further increased. The permeability test results showed that the hydraulic conductivity was approximately constant in the presence of a 6% mineral mass. Thus, it was revealed that it is possible to control the strength of treated sand by adjusting the amount of precipitated minerals.
温度・拘束圧・持続載荷期間に依存する堆積岩不連続面の変形・透水特性
木下尚樹, 安原英明
Journal of MMIJ 133 3 53 - 57 2017年03月 [査読有り]
研究論文（学術雑誌）
動的シミュレーションによる高エネルギー吸収型落石防護網の性能評価
木下尚樹, 安原英明, 矢田部龍一, 加賀山肇
Journal of MMIJ 133 3 46 - 52 2017年03月 [査読有り]
研究論文（学術雑誌）
Optimization of Enzyme-Mediated Calcite Precipitation as a Soil-Improvement Technique: The Effect of Aragonite and Gypsum on the Mechanical Properties of Treated Sand
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita, Akira Hirata
CRYSTALS 7 2 doi:10.3390/cryst7020059 2017年02月 [査読有り]
研究論文（学術雑誌）
The effectiveness of magnesium as a substitute material in enzyme-mediated calcite precipitation was evaluated. Magnesium sulfate was added to the injecting solution composed of urea, urease, and calcium chloride. The effect of the substitution on the amount of precipitated materials was evaluated through precipitation tests. X-ray powder diffraction and scanning electron microscopy analyses were conducted to examine the mineralogical morphology of the precipitated minerals and to determine the effect of magnesium on the composition of the precipitated materials. In addition to calcite, aragonite and gypsum were formed as the precipitated materials. The effect of the presence of aragonite and gypsum, in addition to calcite, as a soil-improvement technique was evaluated through unconfined compressive strength tests. Soil specimens were prepared in polyvinyl chloride cylinders and treated with concentration-controlled solutions, which produced calcite, aragonite, and gypsum. The mineralogical analysis revealed that the low and high concentrations of magnesium sulfate effectively promoted the formation of aragonite and gypsum, respectively. The injecting solutions which produced aragonite and calcite brought about a significant improvement in soil strength. The presence of the precipitated materials, comprising 10% of the soil mass within a treated sand, generated a strength of 0.6 MPa.
A synthesis of approaches for modelling coupled thermal–hydraulic–mechanical–chemical processes in a single novaculite fracture experiment
Alexander E. Bond, Ivan Brusky・Tianqing Cao・Neil Chittenden・Randall Fedors, Xia-Ting Feng・Jin-Ping Gwo, Olaf Kolditz・Philipp Lang・Christopher McDermott・Ivars Neretnieks・Peng-Zhi Pan・Jan Sembera・Hua Shao・Nori Watanabe・Hide Yasuhara・Hong Zheng
Environmental Earth Sciences 76 1 DOI10.1007/s12665-016-6326-6 2017年01月 [査読有り]
研究論文（学術雑誌）
The geological formation immediately surrounding a nuclear waste disposal facility has the potential to undergo a complex set of physical and chemical processes starting from construction and continuing many years after closure. The DECOVALEX project (DEvelopment of COupled models and their VALidation against EXperiments) was established and maintained by a variety of waste management organisations, regulators and research organisations to help improve capabilities in experimental interpretation, numerical modelling and blind prediction of complex coupled systems. In the present round of DECOVALEX (D-2015), one component of Task C1 has considered the detailed experimental work of Yasuhara et al. (Earth Planet Sci Lett 244: 186-200, 2006), wherein a single artificial fracture in novaculite (micro-or crypto-crystalline quartz) is subject to variable fluid flows, mechanical confining pressure and different applied temperatures. This paper presents a synthesis of the completed work of six separate research teams. A range of approaches are presented including 2D and 3D high-resolution coupled thermo-hydro-mechanical-chemical models. The results of the work show that while good, physically plausible representations of the experiment can be obtained using a range of approaches, there is considerable uncertainty in the relative importance of the various processes, and that the parameterisation of these processes can be closely linked to the interpretation of the fracture surface topography at different spatial scales.
Evolution of mechanical and hydraulic properties in sandstone induced by simulated mineral trapping of CO2 geo-sequestration
Hideaki Yasuhara, Naoki Kinoshita, Dae Sung Lee, Junhyung Choi, Kiyoshi Kishida
INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL 56 155 - 164 2017年01月 [査読有り]
研究論文（学術雑誌）
CO2 geological storage has been studied as a countermeasure against global warming. When the injected CO2 reacts with rock minerals, some portion of it may ultimately precipitate to carbonate minerals, such as calcite, and become trapped within the injected reservoir. Although it is of significant importance to examine how the trapped minerals exert an influence on the mechanical, hydraulic, and transport properties of the targeted reservoir rocks, because the minerals may affect the integrity of these rocks, such works are quite sparse in the literature. In this study, the influence of mineral trapping on the evolution of the physical properties was evaluated by replicating the precipitation of calcite that may occur in the mineral-trapping process. The calcite precipitation was enhanced artificially to occur within the void spaces of Berea sandstone. Subsequently, the treated samples were examined through mechanical and permeability experiments. The experimental results revealed that an approximately 10% substitution of the void spaces by the precipitated calcite increased the elastic modulus twofold and the uniaxial compressive strength (UCS) by 20%, and decreased the permeability by one order of magnitude. A cementation theory revealed the process of the calcite precipitation occurring on the free-surface of grains. Predictions of the permeability, using the Kozeny-Carman equation, suggest that variations in permeability imply an increase in surface roughness of the composed grains due to calcite precipitation. (C) 2016 Elsevier Ltd. All rights reserved.
Development of approaches for modelling coupled thermal–hydraulic–mechanical–chemical processes in single granite fracture experiments
Alexander E. Bon, Ivan Brusky・Neil Chittenden, Xia-Ting Feng, Olaf Kolditz・Philipp Lang・Renchao Lu, Christopher McDermott, Ivars Neretnieks・Peng-Zhi Pan・Jan, Šembera・Hua Shao・Hide Yasuhara・Hong Zheng
Environmental Earth Sciences 75 19 2016年10月 [査読有り]
研究論文（学術雑誌）
The geological formation immediately surrounding a nuclear waste disposal facility has the potential to undergo a complex set of physical and chemical processes starting from construction and continuing many years after closure. The DECOVALEX project (DEvelopment of COupled models and their VALidation against EXperiments) was established and maintained by a variety of waste management organizations, regulators and research organizations to help improve capabilities in experimental interpretation, numerical modelling and blind prediction of complex coupled systems. In the present round of DECOVALEX (D-2015), one component of Task C1 has considered the detailed experimental work of Yasuhara et al. (Appl Geochem 26: 2074-2088, 2011), wherein three natural fractures in Mizunami granite are subject to variable fluid flows, mechanical confining pressure and different applied temperatures. This paper presents a synthesis of the completed work of six separate research teams, building on work considering a single synthetic fracture in novaculite. A range of approaches are presented including full geochemical reactive transport modelling and 2D and 3D high-resolution coupled thermohydro- mechanical-chemical (THMC) models. The work shows that reasonable fits can be obtained to the experimental data using a variety of approaches, but considerable uncertainty remains as to the relative importance of competing process sets. The work also illustrates that a good understanding of fracture topography, interaction with the granite matrix, a good understanding of the geochemistry and the associated multi-scale THMC process behaviours is a necessary pre-cursor to considering predictive models of such a system.
Coupled thermo-hydro-mechanical-chemical modeling by incorporating pressure solution for estimating the evolution of rock permeability
Hideaki Yasuhara, Naoki Kinoshita, Sho Ogata, Dae-Sung Cheon, Kiyoshi Kishida
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 86 104 - 114 2016年07月 [査読有り]
研究論文（学術雑誌）
A coupled THMC numerical model has been developed to examine the long-term change in permeability of the porous sedimentary rocks that are assumed to be composed purely of quartz. Specifically, the chemo-mechanical process of the pressure solution was incorporated into the model. The developed model was validated by replicating the existing experimental measurements of the porosity reduction and the evolving silica concentration. Subsequently, by simulating the burial of high-level radioactive wastes in the deep subsurface, namely, by applying the simulated confining pressure and temperature conditions, the long-term evolution of the rock permeability was predicted. The model predictions clearly showed a significant influence of the pressure dissolution on the change in permeability with time. The predicted permeability of the rocks close to the wastes decreased by one order of magnitude in 10(4) years when considering the pressure dissolution, while the permeability changed little during the same period when the pressure dissolution was not considered. This reduction should delay the dispersion of the radioactive materials dissolved in the groundwater. (C) 2016 Elsevier Ltd. All rights reserved.
Critical state modeling of sedimentary rock incorporating healing and decay of rock friction
Nguyen, V. P. Q, Kikumoto, M, Yasuhara, H, Kishida, K
Proc. of the 50th U.S. Rock Mechanics Geomechanics Symposium 2016年06月 [査読有り]
研究論文（国際会議プロシーディングス）
Experimental study on shear strength recovery of single rock joint under thermal conditions
Kiyoshi KISHIDA, Naoya TSUDA, Takao YANO, Hideaki YASUHARA
Japanese Geotechnical Journal 11 1 11 - 20 2016年 [査読有り]
研究論文（学術雑誌）
加温条件下での岩石不連続面のせん断応力回復に関する実験的研究
岸田潔, 津田直弥, 矢野隆夫, 安原英明
地盤工学ジャーナル 11 11 - 20 2016年 [査読有り]
研究論文（学術雑誌）
Effect of Magnesium as Substitute Material in Enzyme-Mediated Calcite Precipitation for Soil-Improvement Technique
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita, Debendra Neupane, Chih-Wei Lu
Frontiers in Bioengineering and Biotechnology 4 37 doi: 10.3389 2016年 [査読有り]
研究論文（学術雑誌）
Distribution of grout material within 1-m sand column in insitu calcite precipitation technique
Debendra Neupane, Hideaki Yasuhara, Naoki Kinoshita, Heriansyah Putra
SOILS AND FOUNDATIONS 55 6 1512 - 1518 2015年12月 [査読有り]
研究論文（学術雑誌）
This study evaluates the potential of improving an insitu calcite grouting technique. The grout is composed of an equimolar solution of urea CaCl2 and an enzyme named urease. We examine the distribution of the grout materials and precipitated calcite within sand columns with a diameter of 5 cm and a height of 100 cm. In the first series of experiments, the concentration distributions of the individual grout materials (i.e., urea, CaCl2 and urease) within the sand specimen are evaluated. In the second series of experiments, an enzyme-reagent mixed solution (i.e., grout) is injected into the sand columns to evaluate the distribution of calcite. Sand samples are collected from various vertical locations within the treated columns and the amount of precipitated calcite is evaluated. Furthermore, attempts are made to achieve the uniform distribution of the injected grout and hence uniform calcite distribution throughout the specimen. The results show that a uniform distribution of the grout materials up to a distance of 1 m from the inlet is achievable. It is also observed that a relatively uniform distribution of calcite is achievable as long as the rate of calcite precipitation is well controlled. (C) 2015 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.
CO2地中貯留の鉱物トラップ再現実験による砂岩の力学・透水特性評価
安原英明, 柏木亮太, 木下尚樹, LEE Dae Sung, 岸田潔
J MMIJ 131 8/9 497 - 502 2015年08月 [査読有り]
研究論文（学術雑誌）
Measurements of Fracture Aperture in Granite Core Using Microfocus X-Ray CT and Fluid Flow Simulation
KISHIDA K, Ishikawa, T, Higo, Y, Sawada, A, Yasuhara, H
ARMA 15 0485 2015年07月 [査読有り]
研究論文（国際会議プロシーディングス）
Long-term observation of permeability in sedimentary rocks under high-temperature and stress conditions and its interpretation mediated by microstructural investigations
Hideaki Yasuhara, Naoki Kinoshita, Hiroaki Ohfuji, Manabu Takahashi, Kazumasa Ito, Kiyoshi Kishida
WATER RESOURCES RESEARCH 51 7 5425 - 5449 2015年07月 [査読有り]
研究論文（学術雑誌）
In this study, a series of long-term, intermittent permeability experiments utilizing Berea sandstone and Horonobe mudstone samples, with and without a single artificial fracture, is conducted for more than 1000 days to examine the evolution of rock permeability under relatively high-temperature and confining pressure conditions. Effluent element concentrations are also measured throughout the experiments. Before and after flow-through experiments, rock samples are prepared for X-ray diffraction, X-ray fluorescence, and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy to examine the mineralogical changes between pre and postexperimental samples, and also for microfocus X-ray CT to evaluate the alteration of the microstructure. Although there are exceptions, the observed, qualitative evolution of permeability is found to be generally consistent in both the intact and the fractured rock samplesthe permeability in the intact rock samples increases with time after experiencing no significant changes in permeability for the first several hundred days, while that in the fractured rock samples decreases with time. An evaluation of the Damkohler number and of the net dissolution, using the measured element concentrations, reveals that the increase in permeability can most likely be attributed to the relative dominance of the mineral dissolution in the pore spaces, while the decrease can most likely be attributed to the mineral dissolution/crushing at the propping asperities within the fracture. Taking supplemental observations by microfocus X-ray CT and using the intact sandstone samples, a slight increase in relatively large pore spaces is seen. This supports the increase in permeability observed in the flow-through experiments.
Dis ibution of mineralized carbonate and its quantification method in enzyme mediated calcite precipitation technique
Debendra Neupane, Hideaki Yasuhara, Naoki Kinoshita, Yuji Ando
SOILS AND FOUNDATIONS 55 2 447 - 457 2015年04月 [査読有り]
研究論文（学術雑誌）
This study discusses the possible application of enzyme mediated calcite precipitation, EMCP, as a soil-improvement technique. It explains the experimental works on this EMCP technique. The first part of this paper addresses the different methods for quantifying the amount of calcite precipitated within sand. Two methods, namely, the thermal decomposition method and the CO2 volume evaluation method, are examined. These methods serve to evaluate the calcite distribution within the treated sand. The second part of this paper explains the experimental procedures and the results of drum-can experiments. Homogenous sand specimens, with a diameter of 57 cm and a height of 60 cm, are prepared inside a steel drum-can. A grout solution, comprising urea, urease, and CaCl2, is injected into the centre of the sand specimens. Subsequently, the improved samples within the specimens are collected and their compressive strength is evaluated. The maximum measured unconfined compressive strength is 380 kPa. An attempt is made to relate the improved mechanical properties of EMCP-treated sand to the amount of mineralized carbonate. The obtained calcite-strength relation is found to be in close agreement with the relation obtained in previous literature. (C) 2015 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.
圧力溶解現象を考慮した数値解析モデルによる岩盤の長期透水特性評価
安原英明, 緒方奨, 木下尚樹, 岸田潔
土木学会論文集 C(地圏工学)(Web) 71 4 292 - 300 Japan Society of Civil Engineers 2015年 [査読有り]
研究論文（学術雑誌）
放射性廃棄物地層処分施設近傍の岩盤の水理学特性を詳細に把握することは，安全に処分事業を進めるうえで必要不可欠である．周辺岩盤には，掘削影響による応力場の変化，廃棄体からの放熱，地熱や地殻応力による地化学反応が複合的に絡みあい，各現象を統合的に評価する必要がある．本研究では，岩石構成粒子接触部における圧力溶解現象を考慮した熱・水・応力・化学連成解析モデルを開発し，放射性廃棄物地層処分施設の周辺岩盤の透水性の長期予察解析を行った．その結果，圧力溶解現象を考慮しない場合，周辺岩盤の透水性変化は確認されず，圧力溶解現象を考慮した場合は，時間の経過と共に透水性が最大1オーダー程度低下する傾向が得られた．
Structural Healing and Decay of Sedimentary Soft Rock in Triaxial Slide-Hold-Slide, Process and Its Modeling
Kikumoto, M, Vu, N.P.Q, Ohno, M, Kishida, K, Yasuhara, H, Elsworth, D
Proceedings of the 2014 ISRM International Symposium – 8th Asian Rock Mechanics Symposium 536 - 545 2014年10月 [査読有り]
Discussion on Friction Factor of Single Rock Joint under Slide-Hold-Slide Process in Considering Influence of Thermal Conditions
Tsuda, N, Yasuhara, H, Yano, T, Kishida, K
Proceedings of the 2014 ISRM International Symposium – 8th Asian Rock Mechanics Symposium 263 - 269 2014年10月 [査読有り]
Mechanical Behavior of Rock Joints with Various Kinds of Joint Surface Roughness under Cyclic Direct Shear Loading Conditions
Maskey, S, Yasuhara, H, Kishida, K
Proceedings of the 2014 ISRM International Symposium – 8th Asian Rock Mechanics Symposium 231 - 238 2014年10月 [査読有り]
Evolution of Permeability in Granite Fracture under High pH Conditions
Yasuhara, H, Kinoshita, N, Maeta, K, Nakashima, S, Kishida, K
Proceedings of the 2014 ISRM International Symposium - 8th Asian Rock Mechanics Symposium 1977 - 1982 2014年10月研究論文（学術雑誌）
Evolution of Mechanical and Hydraulic Properties in Sandstone Induced by Mineral Trapping
Yasuhara, H, Kinoshita, N, Nakashima, S, Kishida, K
ARMA 2014 14 7112 2014年06月 [査読有り]
研究論文（国際会議プロシーディングス）
Time Dependency Friction Factor of Rock Single Fracture under Slide-Hold-Slide Direct shear experiments
Kishida, K, Tsuda, N, Yano, T, Yasuhara, H
ARMA 2014 14 7388 2014年06月 [査読有り]
研究論文（国際会議プロシーディングス）
生体触媒を活用した炭酸カルシウム結晶析出による地盤固化効果の検討
安原英明, NEUPANE Debendra, 木下尚樹, 林和幸, 海野寿康
土木学会論文集 C(地圏工学)(Web) 70 2 290 - 300 Japan Society of Civil Engineers 2014年 [査読有り]
研究論文（学術雑誌）
本研究では，生体触媒であるウレアーゼの尿素加水分解機能を利用した炭酸カルシウム結晶析出による地盤固化効果の検討を行った．まず，直径50mm，高さ100mmの円柱砂供試体に所定の濃度に調整したグラウト材を注入し，改良体の力学特性を評価した．その結果，炭酸カルシウム析出量の増加と共に強度が増加する正の相関が得られた．つぎに，より大型な砂地盤内にグラウト材を注入することにより，砂地盤の固化程度を評価するために，ドラム缶内に直径560mm，高さ600mmの砂層地盤を作製し，濃度調整したグラウト材の注入試験を実施した．その結果，概ね想定した領域を改良することができ，本手法の有用性を示すことができたが，改良体の強度制御が今後の課題であることが確認された．
熱環境下における岩石不連続面の透水特性に及ぼす化学・力学連成作用
木下尚樹, 安原英明, 橋本克樹
J MMIJ 129 7 485 - 491 The Mining and Materials Processing Institute of Japan 2013年07月 [査読有り]
研究論文（学術雑誌）
In radioactive waste disposal, tunnel passing through the ground with high geothermal region, and hot water temporary storage system, the rock mass around the openings will be influenced by coupled chemo-mechanical behavior induced by high temperatures. Then, rock fractures may be hydraulic weakness on low-permeability rock mass. Therefore, the coupled behavior should be examined to evaluate hydraulic property of rock fractures. In this study, flow-through experiments on a single fracture in granite have been carried out under confining pressure and temperature conditions controlled. The fracture permeability monotonically decreased with time at room temperature, and reached a quasi-steady state. Then, after the temperature was raised to 90 ºC, the permeability decreased again throughout the rest of the experiments. The elemental concentrations in fluid samples taken from the outlet were evaluated by ICP-AES. The elemental concentrations increased with increase of temperature. Thus, this behavior should be attributed to coupled chemo-mechanical effects. Meanwhile, another suite of sustained loading experiments using the same granite has been conducted under controlled temperature, confining pressure and mineral dissolution conditions for the purpose of evaluating the deformation behavior of rock fractures. From the tests results, it is found that the difference in compression behavior of the fractures is very small for all the conditions. However, particularly, it is found that displacement of the fractured rock sample under the wet and high temperature conditions is larger than those under the other conditions. The reason for this may be due to microscopic failure and mineral dissolution at the asperity contact areas.
Long-term Observation of Rock Permeability under High Pressure and Temperature Conditions and Its Microstructural Interpretation
Yasuhara, H, Kinoshita, N, Takahashi, M, Nakashima, S, Kishida, K
ARMA 2013 13 236 2013年06月 [査読有り]
研究論文（国際会議プロシーディングス）
An evaluation of the effects of fracture diagenesis on hydraulic fracturing treatment
Dae Sung Lee, Hideaki Yasuhara
Geosystem Engineering 16 1 113 - 118 2013年03月 [査読有り]
研究論文（学術雑誌）
The rates and magnitudes of fracture permeability on commercially available proppants were determined from flow through experiments at different stresses and temperatures for hydraulically open and closed systems. A pressure solution model describing multi-mineral dissolution behavior is extended to accommodate the specific nature of the compaction of the synthesized proppant with different chemical compositions. Mechanisms include multi-mineral dissolution, transport, and re-precipitation at the contacting asperities and the free walls within the fractures, resulting in a loss of porosity in proppant packs. The mechanistic model used recovered thermodynamic and kinetic data for mineralogical composition of available proppants within rigid-walled fluid pressure only furnace and ambient stress quadcell reactors. Under reservoir temperature of 191°C and stresses of 65.5 MPa, these ensemble data suggest that proppant packs may compact by up to 10% over the period of a few years. © 2013 Copyright Taylor and Francis Group, LLC.
拘束圧・温度に依存する花崗岩不連続面の不可逆透水特性に関する実験的評価
安原英明, 長谷川大貴, 中島伸一郎, 矢野隆夫, 岸田潔
地盤工学ジャーナル(Web) 8 1 71 - 79 The Japanese Geotechnical Society 2013年 [査読有り]
研究論文（学術雑誌）
温度・応力条件に依存する岩石構成鉱物の溶解現象に起因する岩盤の透水・物質輸送特性の空間的・時間的変化を把握することは重要である。本研究では，加温することが可能な三軸試験装置を用いて，単一不連続面を有する花崗岩供試体に対して，温度を20および90℃に，拘束圧を1～10 MPaに制御した環境で透水試験を実施し，温度・拘束圧に依存する透水特性の変化を計測した。また，拘束圧の保持時間が透水特性に与える影響を検証するために，短期載除荷試験，長期保持試験の2種類の実験を実施した。その結果，20℃条件では透水特性の変化に可逆的な挙動が観察されたが，90℃条件では，不可逆的な挙動が得られた。これは，不連続面内アスペリティ接触部の破壊・溶解現象に起因していると考えられる。
Estimation of fracture flow considering the inhomogeneous structure of single rock fractures
Kiyoshi Kishida, Atsushi Sawada, Hideaki Yasuhara, Takashi Hosoda
Soils and Foundations 53 1 105 - 116 2013年 [査読有り]
研究論文（学術雑誌）
Considering the safe, long-term isolation of energy byproducts, such as radioactive waste, one of the important parameters is the velocity of the groundwater flow through the void of rock masses and/or fractures. Although it is generally known that a natural rock fracture indicates a complex aperture distribution, the fracture is often ideally represented by a parallel plate model. The cubic law is applied to evaluate the hydraulic properties of fractured rock. From several previous research works, it is understood that the cubic law can be applied when the Reynolds number is less than 1.0 and that the inertia term can basically be ignored in such slow fracture flows. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model, in which the inertia term, the pressure term and the diffusion term are incorporated, are carried out for single fracture permeability tests under conditions which allow for the application of the cubic law. In comparing the results of the experiments with the results of the numerical simulation, the results of the simulation employing the 2D model show a good agreement with the experimental results the 2D model can simulate the water flow in an inhomogeneous fracture more accurately than the simulation based on the local cubic law. From these simulation results, the fracture flow in an inhomogeneous structure is discussed, along with the local Reynolds number, and the resistance through the fracture geometry is considered. Consequently, under the condition of a mean Reynolds number of less than 1.0, the inertia terms do not affect the fracture flow, but the hydraulic resistance does affect the fracture flow. © 2013 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.
Applicability of enzymatic calcium carbonate precipitation as a soil-strengthening technique
Debendra Neupane, Hideaki Yasuhara, Naoki Kinoshita, Toshiyasu Unno
Journal of Geotechnical and Geoenvironmental Engineering 139 12 2201 - 2211 2013年 [査読有り]
研究論文（学術雑誌）
A grouting technique for enzymatic calcite precipitation is evaluated. Urea and calcium salt, at various concentrations, are mixed with a concentration-fixed enzyme to obtain the optimal precipitation of CaCO3. The optimally combined solution is injected into sand samples in small PVC cylinders. Then, the improvement in small-scale samples is observed. The combination, approved for small-scale tests, is further used for larger-scale tests. The porosity distribution within the soil is evaluated by sampling the treated sand at different locations. A precipitation ratio up to 80% can be obtained using a small amount of the enzyme. The results show that the in situ enzymatic CaCO3 precipitation technique may be feasible for use in larger-scale applications. A multiphysics simulator that considers the calcite precipitation reaction during the transport of the solution is adopted to predict the evolution of the porosity. The predicted porosities are compared with the measured porosities. The results show that the numerical predictions can replicate the actual changes in porosity relatively well and that the numerical model should be helpful in assuming these changes caused by the precipitated CaCO3 induced by the grouting technique examined in this work. © 2013 American Society of Civil Engineers.
製紙スラッジ焼却灰造粒材料を用いたモルタルのプレキャスト材料としての性能評価
木下尚樹, 川口隆, 松尾暁, 本田美紀, 安原英明
J MMIJ 128 12 611 - 619 The Mining and Materials Processing Institute of Japan 2012年11月 [査読有り]
研究論文（学術雑誌）
The paper sludge which is generated during paper manufacturing processes is incinerated to reduce its volume, and then the paper sludge ash is produced. The greater part of the paper sludge ash has been disposed to landfills and an effective utilization of the paper sludge ash has not been promoted. From view point of the effective utilization of industrial wastes, the authors have proposed that the granulated materials made of the paper sludge ash are used for concrete aggregate and evaluated the applicability of paper sludge ash to concrete. The concrete using the granulated paper sludge ash is lighter, and its water absorption is much higher than those of ordinary concretes. The drying shrinkage strain is larger than that of ordinary concretes.
The lightweight precast materials used for such as forms have a merit of the cost reduction of transportation and construction. In this study, the applicability of the mortar using granulated paper sludge ash for aggregate (PS mortar) to precast lining form is examined. Firstly, the flowability and the strength of the PS mortar are examined and the curing performance of the PS mortar form is indirectly evaluated by measuring strength and air tightness of back filling concrete. Secondly, the drying shrinkage of the PS mortar is measured and its prediction equation is proposed. Finally, Practicality of the PS mortar to precast materials is evaluated by observing deformation and crack occurring of the precast PS mortar walls constructed tentatively in this study. From results of the above examinations, it is found that the PS mortar form has a high curing performance. However, the PS mortar may not be unconditionally utilized because its drying shrinkage strain is relatively large.
Spontaneous alternation of rock permeability under constant confining pressure and temperature conditions
Yasuhara, H, Takahashi, M, Kinoshita, N, Nakashima, S, Kishida, K
Proceedings of 7th Asian Rock Mechanics Symposium 972 - 981 2012年10月 [査読有り]
研究論文（国際会議プロシーディングス）
製紙スラッジ焼却灰造粒材料のコンクリート用骨材としての適用性評価
木下尚樹, 川口隆, 松尾暁, 安原英明
J MMIJ 128 10/11 576 - 583 The Mining and Materials Processing Institute of Japan 2012年09月 [査読有り]
研究論文（学術雑誌）
There are many paper mills in the eastern area of Ehime Prefecture where the pulp and paper industry has been well developed. Paper sludge containing large amounts of water is generated during paper manufacturing processes. The paper sludge is incinerated to reduce its volume, and then the paper sludge ash is produced. The greater part of the paper sludge ash has been disposed to landfills and an effective utilization of the paper sludge ash has not been promoted. Due to environmental policy and regulations in Japan, it will become difficult to obtain supplies of river sand and sea-bed sand which have been used for concrete aggregate. On the other hand, demands for the effective utilization of industrial wastes for construction materials that are typically made of natural resources will rise in future. From this background, the authors propose an effective utilization of granulated paper sludge ash produced from the paper mills as concrete aggregate.
In this study, the applicability of granulated materials made of the paper sludge ash to concrete aggregate is evaluated by carrying out the following experiments. Firstly, the physical and chemical properties of the paper sludge ash are evaluated and a mixture proportion of the granulated paper sludge ash is examined through its strength measured by point load tests. Secondly, Particle size distribution, density, water absorption rate, and solid content of the granulated paper sludge ash are evaluated from the view point of concrete aggregate. Finally, durability, mechanical and physical properties of concretes mixed with the granulated paper sludge ash used as proxy of sand aggregate are also evaluated. From results of the above experiments, it is found that the concrete using the granulated paper sludge ash is lighter, and its water absorption is much higher than those of ordinary concretes. The strength can satisfy the requisite for design standards of reinforced concretes. The drying shrinkage strain is larger and the air tightness is lower than those of ordinary concretes.
Experiments and predictions of physical properties of sand cemented by enzymatically-induced carbonate precipitation
Hideaki Yasuhara, Debendra Neupane, Kazuyuki Hayashi, Mitsu Okamura
SOILS AND FOUNDATIONS 52 3 539 - 549 2012年06月 [査読有り]
研究論文（学術雑誌）
A grouting technique that utilizes precipitated calcium carbonate as a cementing material is presented. The enzyme urease is used to enhance the rate and the magnitude of the calcium carbonate precipitation. Evolutions in the mechanical and the hydraulic properties of treated sand samples are examined through unconfined compression and permeability tests, respectively. The grout is mainly composed of urease, which bio-catalyzes the hydrolysis of urea into carbon dioxide and ammonia, urea, and calcium chloride solutions. This method employs chemical reactions catalyzed by the enzyme, and ultimately acquires precipitated calcium carbonate within soils. The mechanical test results show that even a small percentage of calcium carbonate, precipitated within soils of interest, brings about a drastic improvement in the strength of the soils compared to that of untreated soils the unconfined compressive strength of the samples treated with < 10 vol% calcium carbonate precipitation against the initial pore volume ranges from similar to 400 kPa to 1.6 M Pa. Likewise, the hydraulic test results indicate the significant impervious effects of the grouting technique the permeability of the improved samples shows more than one order of magnitude smaller than that of the untreated soils. Evolutions in the measured hydraulic conductivity and porosity are followed by a flow simulator that accounts for the solute transport process of the injected solutions and the chemical reaction of the calcite precipitation. Predictions of the changes in permeability with time overestimate the test measurements, but those of the changes in porosity show a good agreement with the actual measurements, indicating that such simulations should become a significant supplementary tool when considering real site applications. (C) 2012 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved.
温度・pHを制御したフロースルー溶解試験による花崗岩溶解速度定数式の提案とその妥当性の検討
安原英明, 橋本克樹, 木下尚樹
J MMIJ 128 2 79 - 85 The Mining and Materials Processing Institute of Japan 2012年01月 [査読有り]
研究論文（学術雑誌）
When considering a geological isolation of high level radioactive wastes, the evolutions of the mechanical, hydraulic, and transport properties of the targeted rocks should be evaluated in advance because those may be degraded by the coupled thermal, hydraulic, mechanical, and chemical effects induced by the emplacement of the wastes. Chemical reactions such as mineral dissolution and precipitation that is dependent on temperature and pH conditions, may be one of the key issues that may trigger off the degradation. Therefore, the dissolution mechanism of the targeted rocks should be thoroughly examined under various temperature and pH conditions.
In this work, a suit of flow-through experiments in granite has been conducted at temperatures of 30, 50, and 70°C, and at pHs of 6, 9, and13, to examine the granite dissolution behavior. An apparent dissolution rate equation of the granite is defined under arbitrary temperature and pH conditions. The acquired dissolution rates are compatible to those evaluated in the literature. Utilizing the dissolution rates, the evolution of the element concentrations measured in the permeability experiments on the granite fracture is replicated. The predicted concentrations follow the experimental measurements both qualitatively and quantitatively. Although showing in a good agreement with the experimental measurements, the predictions slightly underestimate the actual. This is attributed likely to the unaccounted effects of mineral dissolution at the contacting asperities, indicating that a more sophisticated dissolution equation should be achieved by considering such a dissolution mechanism.
熱・拘束圧環境下における不連続面を有する花崗岩の透水性評価
木下尚樹, 安原英明
J MMIJ 128 2 72 - 78 The Mining and Materials Processing Institute of Japan 2012年01月 [査読有り]
研究論文（学術雑誌）
From the viewpoints of multiple-utilization of land, environmental safeguards, energy conservation, etc, a temporary storage of hot water in openings excavated in rock may be worthwhile. In this case, the rock mass around the openings will respond by coupled thermo-mechanical effects induced by the hot water.
In this study, flow-through experiments on a single fracture in granite has been carried out under confining pressures of 5-10 MPa, and at temperatures of 20-90°C. The fracture aperture and the permeability monotonically decreased with time at room temperature, and reached a quasi-steady state. Then, after the temperature was raised to 90°C, the aperture decreased again throughout the rest of the experiments. Fluid samples were taken from the outlet to examine the elemental concentrations that were evaluated by inductively-coupled plasma atomic emission spectrometry (ICP-AES) . The elemental concentrations increased with increase of temperature. After the flow-through experiments, the fracture surface was observed by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX) . The formation of a few kinds of precipitated minerals such as silica and calcite was revealed. The precipitation was limited to quite local and small areas. However, the precipitated minerals seemed to have had some influences on the permeability.
Temporal alteration of fracture permeability in granite under hydrothermal conditions and its interpretation by coupled chemo-mechanical model
Hide Yasuhara, Naoki Kinoshita, Hiroaki Ohfuji, Dae Sung Lee, Shinichiro Nakashima, Kiyoshi Kishida
APPLIED GEOCHEMISTRY 26 12 2074 - 2088 2011年12月 [査読有り]
研究論文（学術雑誌）
Examining the evolution of fracture permeability under stressed and temperature-elevated conditions, a series of flow-through experiments on a single rock fracture in granite has been conducted under confining pressures of 5 and 10 MPa, under differential water pressures ranging from 0.04 to 0.5 MPa, and at temperatures of 20-90 degrees C, for several hundred hours in each experiment. Measurements of fluid and dissolved mass fluxes, and post-experimental microscopy, were conducted to constrain the progress of mineral dissolution and/or precipitation and to examine its effect on transport properties. Generally, the fracture aperture monotonically decreased with time at room temperature, and reached a steady state in relatively short periods (i.e., <400 h). However, once the temperature was elevated to 90 degrees C, the aperture resumed decreasing and kept decreasing throughout the rest of the experimental periods. This reduction may result from the removal of the mineral mass from the bridging asperities within the fracture. Post-experimental observations by scanning electron microscopy, coupled with energy dispersive X-ray spectroscopy (SEM-EDX), revealed the formation of several kinds of secondary minerals such as silica and calcite. However, the precipitated minerals seemed to have had little influence on the flow characteristics within the fracture, because the precipitation was limited to quite local and small areas. The evolving rates and ultimate magnitudes of the fracture aperture are likely to be controlled by the stress exerted over the contacting asperities and temperatures, and by the prescribed flow conditions. Thus, this complex behavior should be attributed to the coupled chemically-and mechanically-induced effect. A coupled chemo-mechano conceptual model, accounting for pressure and free-face dissolutions, is presented in this paper to follow the evolution of the fracture permeability observed in the flow-through experiments. This model addresses the two dissolution processes at the contacting asperities and the free walls within the fractures, and is also capable of describing multi-mineral dissolution behavior. The model shows that the evolution of a fracture aperture (or related permeability) and of element concentrations may be followed with time under arbitrary temperature and pressure conditions. The model predictions for the evolving fracture aperture and elements concentrations show a relatively good agreement with the experimental measurements, although it is not possible to replicate the abrupt reduction observed in the early periods of the experiments, which is likely to be due to an unaccounted mechanism of more stress-mediated fracture compaction driven by the fracturing of the propping asperities. (C) 2011 Elsevier Ltd. All rights reserved.
In-Situ Desaturation Test by Air Injection and Its Evaluation through Field Monitoring and Multiphase Flow Simulation
Mitsu Okamura, Masaya Takebayashi, Katsuji Nishida, Nao Fujii, Motoharu Jinguji, Takehiko Imasato, Hideaki Yasuhara, Emiko Nakagawa
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING 137 7 643 - 652 2011年07月 [査読有り]
研究論文（学術雑誌）
Desaturation of ground by air injection attracts considerable attention in recent years as an innovative technique for a liquefaction countermeasure. Several research programs were conducted in laboratories regarding the related topics. This paper describes an in situ air-injection test that aims to examine the effectiveness of the air injection to desaturate ground and the validity of observation techniques to monitor the evolution of the unsaturated zone. In the test, air was injected from an air injector deployed in a targeted saturated-sand layer at a depth of 6 m. Observations revealed that the air-flow rate increased linearly with increasing air-injection pressure and the desaturated zone was generated within 4 m from the injection point. A 3-dimensional electric resistivity tomography technique was effective for evaluation of the desaturated zone. The degree of saturation of the in situ soil was observed by using high quality undisturbed samples obtained by the ground freezing method. The degree of saturation ranged from 68-98%, which was low enough to almost double the liquefaction resistance of the soil at the site. Numerical analyses were also conducted with a gas-liquid two-phase flow simulator to describe the evolution of the soil desaturation. Qualitatively, predictions show a relatively good agreement with the in situ measurements of the 3D electric resistivity tomography and are quantitatively compatible with the in-field degree of saturation measured indirectly by using the frozen soil samples. Actual liquefaction resistance was evaluated utilizing the undisturbed samples by conducting a triaxial test under cyclic shear conditions, which revealed that desaturated samples were indeed less susceptible to liquefaction compared with the fully saturated samples. DOI: 10.1061/(ASCE)GT.1943-5606.0000483. (C) 2011 American Society of Civil Engineers.
Estimation of shear strength recovery and permeability of single rock fractures in shear-hold-shear type direct shear tests
Kiyoshi Kishida, Yuta Kawaguchi, Shinichiro Nakashima, Hideaki Yasuhara
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 48 5 782 - 793 2011年07月 [査読有り]
研究論文（学術雑誌）
The evolution of the long-term mechanical, hydraulic, and transport characteristics of rock fractures should be predicted in advance by considering the issue of the underground deposits of the energy byproducts of high-level radioactive waste. This paper presents slide-hold-slide direct shear-flow coupling experiments conducted for mortar and granite specimens with single fractures so as to investigate the effects of load holding on the mechanical properties of rock joints. From the experimental results, it is confirmed that the shear strength of the mortar replica specimens increases and the permeability decreases during 3 days of load holding. However, no significant changes are observed for the mechanical or the hydro-mechanical properties of the granite specimen even after 20 days of load holding. It is also confirmed that the shear strength of the mortar specimens increases in both short- and long-time holding cases. However, the evolution of shear strength recovery is found to be different for the two cases. This is because the dominant factor in the shear strength recovery during short-time holding may be attributed to a purely mechanical process, like creep deformation at the contacting asperities, while the shear strength recovery during long-time holding is affected by both mechanical and chemical processes. Moreover, to reproduce the shear strength recovery during short-time holding, we develop a direct shear model by employing a temporal variation in the dilation that occurs during load holding. The model predictions are in relatively good agreement with the experimental observations in the range of the short-holding period. (C) 2011 Elsevier Ltd. All rights reserved.
Thermally Induced Behavior of the Openings in Rock Mass Affected by High Temperatures
Naoki Kinoshita, Hide Yasuhara
INTERNATIONAL JOURNAL OF GEOMECHANICS 11 2 124 - 130 2011年04月 [査読有り]
研究論文（学術雑誌）
The temporary storage of hot water in openings excavated in rock may be worthwhile for multiple land-use applications, environmental safeguards, and energy conservation. When used for hot water storage, the rock mass around the openings will respond by coupled thermomechanical effects induced by the hot water. In this study, a submergence test of granite and sandstone at 20 and 95 degrees C was used to examine the thermal behavior of the rock mass around the openings to obtain the mechanical properties of uniaxial compressive strength and elastic modulus. A uniaxial compression creep test of the rock at high temperatures was also performed and calculations with various constants for the creep were examined. With the results obtained in this work, the temperature and stress distribution around the openings when hot water is stored was analyzed by considering the creep properties. The thermal behavior and stability of the openings were also examined. The displacement of the openings was predicted to be approximately 2% of the diameter after 1,000 days. (C) 2011 American Society of Civil Engineers.
間隙水圧・変形連成問題への最近の取り組み岩盤不連続面におけるせん断強度回復現象とその時間依存性
川口雄大, 中島伸一郎, 安原英明, 岸田潔
J MMIJ 127 3 158 - 164 The Mining and Materials Processing Institute of Japan 2011年02月
Evolution of the long-term mechanical, hydraulic, and transport characteristics of rock fractures should be, in advance, predicted in considering an issue on entombment of energy byproducts of high level radioactive wastes. Under stressed and temperature conditions, those behaviors of the rock fractures of interest may be evolved in time and space likely due to the change in topographical aperture distributions. This irreversible process may be induced by pure mechanical and/or chemo-mechanical creeps such as water-rock reactions like stress corrosion and pressure solution, and chemical effects including mineral dissolution and reprecipitation in the free-walls of fractures. Specifically, the chemo-mechanical processes active at the contacting asperities within rock fractures may exert a significant influence on the mechanical, hydraulic, and transport behaviors throughout a long period, and thus, should be vigorously examined theoretically and experimentally.
This paper presents the slide-hold-slide shear test results for fully-saturated, single-jointed mortar specimens so as to investigate the effects of load holding on mechanical properties of rock joints. From the test results, it was confirmed that shear strength increased for mortar specimens in both short and long time holding cases. However, the evolution of shear strength recovery in two cases is different. This is because a dominant factor of shear strength recovery during the short time holding may be attributed to a pure mechanical process like creep deformation at contacting asperities, while the one during long time holding is affected by both mechanical and chemical processes like pressure solution.
Moreover, to reproduce the shear strength recovery during short time holding we develop a direct shear model by including temporal variation of dilation during holding. The model predictions are in relatively good agreement with the test measurements.
Evolution in mechanical and hydraulic properties of calcite-cemented sand mediated by biocatalyst
H. Yasuhara, K. Hayashi, M. Okamura
Geotechnical Special Publication 211 3984 - 3992 2011年研究論文（国際会議プロシーディングス）
A grouting technique that utilizes precipitated calcite as cohesive material is presented. An enzyme of urease is used to enhance the rate and magnitude of the calcite precipitation. Evolutions in the mechanical and hydraulic properties of sand samples treated are examined through the unconfined compression and permeability tests, respectively. The grout is composed mainly of urease that bio-catalyzes the hydrolysis of urea into carbon dioxide and ammonia, urea, and calcium chloride solution. This method employs chemical reactions catalyzed by the enzyme, and ultimately acquires calcite precipitated within soils. The experimental results show that even a small percentage of calcite precipitation against soils of interest improves the strength drastically compared with that of untreated soil. The evolution in hydraulic conductivity measured is replicated by a flow simulator accounting for the chemical reactions. The predictions show good agreement with the actual measurements. © 2011 ASCE.
Experiment and modeling to evaluate the effects of proppant-pack diagenesis on fracture treatments
Dae Sung Lee, Derek Elsworth, Hideaki Yasuhara, Jim D. Weaver, Richard Rickman
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING 74 1-2 67 - 76 2010年10月研究論文（学術雑誌）
Observed reductions in the permeability of propped hydraulic fractures are examined by considering the role of mechanical stresses and the chemistry of pore fluids at elevated temperatures as agents of proppant diagenesis. Stress-enhanced dissolution of proppant increases the density of grain packing and reprecipitation of mineral matter further occludes pores - together these mechanisms additively reduce porosity and permeability. Experiments and analyses are presented which explore the evolution of porosity and permeability in proppant packs subjected to reservoir conditions of stresses to 65 MPa and temperatures to 177 degrees C. Experiments are completed in two modes: in flow-through reactors absent intergranular stresses to evaluate rates of dissolution and reprecipitation on proppant surfaces, and in uniaxially stressed reactors with stagnant fluids to evaluate the relative role of stress in mediating dissolution and porosity reduction. Lumped parameter models are used to evaluate rates of dissolution and chemical compaction in a range of proppants. Mechanisms include mineral dissolution, transport, and reprecipitation of the resulting products in the particle interstices, resulting in a loss of intergranular porosity. The model uses thermodynamic data derived from the reactor experiments to constrain the projected loss of permeability for the mineralogical composition of available proppants. Evaluated silica dissolution rates vary with temperature but are of the order of 1.1 x 10(-11) to 3.1 x 10(-4) mol/m(2)s in the range of 100 degrees C to 288 degrees C. Experimental results show chemical compactions of the order of 10 millistrains over 40 days and these project modeled reductions in porosity of the order of 25% over 1000 days. Rates of porosity loss increase both with an increase in temperature and a decrease in mean grain size of the granular proppant although ultimate porosities at the conclusion of compaction are similar. Rates and magnitudes of ultimate reductions in porosity map directly onto reductions in permeability and for proppants in the range 100 to 600 mu m, result in permeability reductions in the range of 25% (163 degrees C) to 75% (191 degrees C). Such magnitudes (75%) of permeability loss over short periods (1000 days) are consistent with many field observations, with the mechanistic models providing a rational method of scaling such observations. (C) 2010 Elsevier B.V. All rights reserved.
Mechanical and transport constitutive models for fractures subject to dissolution and precipitation
Derek Elsworth, Hideaki Yasuhara
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS 34 5 533 - 549 2010年04月研究論文（学術雑誌）
Transient changes in the permeability of fractures in systems driven far-from-equilibrium are described in terms of proxy roles of stress, temperature and chemistry. The combined effects of stress and temperature are accommodated in the response of asperity bridges where mineral mass is mobilized from the bridge to the surrounding fluid. Mass balance within the fluid accommodates mineral mass either removed from the flow system by precipitation or advection, or augmented by either dissolution or advection. Where the system is hydraulically closed and initially at equilibrium, reduction in aperture driven by the effects of applied stresses and temperatures will be augmented by precipitation on the fracture walls. Where the system is open, the initial drop in aperture may continue, and accelerate, where the influent fluid is oversaturated with respect to the equilibrium mineral concentration within the fluid, or may reverse, if undersaturated. This simple zero-dimensional model is capable of representing the intricate behavior observed in experiments where the feasibility of fracture sealing concurrent with net dissolution is observed. This zero-order model is developed as a constitutive model capable of representing key aspects of changes in the transport parameters of the continuum response of fractured media to changes in stress, temperature and chemistry. Copyright (C) 2009 John Wiley & Sons, Ltd.
負荷状態保持による岩石き裂のせん断強度および透水性の変化
中島伸一郎, 川口雄大, 岸田潔, 安原英明, 矢野隆夫, 細田尚
材料 59 3 211 - 218 The Society of Materials Science, Japan 2010年03月研究論文（学術雑誌）
This paper presents direct shear test results for single jointed granite and mortar specimens to investigate effects of long-term load holding on mechanical and hydrological properties of rock joints. From the test results, it was confirmed that shear strength increased and permeability decreased for mortar specimens through three days load holding. For granite specimens, however, significant change was not confirmed on mechanical and hydrological properties through up to twenty days load holding due to smallness of confining pressure compared with the strength of granite and shortness of load holding. Relationship between the time of shear holding (t_h) and the growth of shear strength during shear holding (Δτ) was examined for mortar specimens. When t_n was shorter than 10⁶sec, Δτ increased in proportional to the logarithm of t_h as Dieterich's log-linear model, which explains the time-dependency of Δτ as increase of contact area of fracture surface due to asperity creep. When t_h was about 10⁶sec, however, Δτ was larger than the value predicted by the Dieterich's log-linear model. This result implies growth of adhesion driven by chemical action at contact area of fracture surface such as pressure solution and precipitation.
IN-SITU TEST ON DESATURATION BY AIR INJECTION AND ITS MONITORING
Mitsu Okamura, Masaya Takebayashi, Katsuji Nishida, Nao Fujii, Motoharu Jinguji, Takehiko Imasato, Hideaki Yasuhara, Emiko Nakagawa
GROUND IMPROVEMENT TECHNOLOGIES AND CASE HISTORIES 151 - 158 2010年 [査読有り]
研究論文（国際会議プロシーディングス）
Desaturation of ground by air injection attracts considerable attention in resent years as an innovative technique for liquefaction countermeasure. Several research programs have been run in laboratories regarding related topics. This paper describes an in-situ air injection test which aimed to confirm the effectiveness of the air injection to desaturate ground and validity of observation techniques to monitor the evolution of unsaturated zone. Degree of saturation of the in-situ soil was observed using high quality undisturbed samples obtained by the ground freezing method. The degree of saturation ranged between 68% and 98%, which was low enough to almost double the liquefaction resistance of the soil at the site. 3D electric resistivity tomography technique was found to be effective to detect evaluation of the desaturated zone.
炭酸カルシウム結晶析出による砂の液状化特性の改善効果
林和幸, 岡村未対, 安原英明
地盤工学ジャーナル 5 2 391 - 400 公益社団法人地盤工学会 2010年
炭酸カルシウム結晶を析出させた砂の液状化特性を明らかにするため，ゆるい炭酸カルシウム析出砂の非排水繰返し三軸試験を行った。また，析出した結晶による砂粒子間のボンディング形成の有無が液状化抵抗に及ぼす影響を調べるため，結晶析出砂を撹乱・再構成し，ボンディングの効果を除去した供試体の試験も行った。その結果，砂供試体中に析出した結晶は，ゆるい砂の液状化強度・変形特性を著しく改善することが分かった。液状化強度の増加は，結晶により形成されたボンディングが主たる要因であること，結晶析出砂の液状化強度は，正規化せん断弾性係数と液状化強度の関係を基に評価できることが明らかとなった。
炭酸カルシウム結晶析出による砂の力学特性の改善効果
林和幸, 只信紗也佳, 安原英明, 岡村未対
土木学会論文集Ｃ 66 1 31 - 42 公益社団法人土木学会 2010年
砂の力学特性に及ぼす炭酸カルシウム結晶析出の効果について，排水条件で三軸圧縮試験を行い定量的に評価した．また，砂粒子間に析出した結晶のボンディングが砂の力学特性に及ぼす影響を確認するため，結晶析出砂を解体し，再構成した供試体を用いて三軸圧縮試験を行った．さらに，エネルギー分散型 X線分光器付き走査型電子顕微鏡 (SEM-EDX)を用いて，析出結晶の同定および微視構造の観察を行った．その結果，有効拘束圧が 30～100kPa，結晶析出量が 0～3%の範囲では，砂粒子表面に析出した炭酸カルシウム結晶による摩擦増加，および正のダイレイタンシーの増加により内部摩擦角は増加すること，せん断初期にボンディングは崩壊すること，結晶によるボンディングはヤング率を増加させることが明らかとなった．
力学‐化学連成概念モデルによる花崗岩不連続面の透水・物質輸送経時解析
安原英明, 木下尚樹, LEE Dae Sung, 中島伸一郎, 岸田潔
土木学会論文集 C(Web) 65 1 41-52 (J-STAGE) - 52 Japan Society of Civil Engineers 2009年
放射性廃棄物や二酸化炭素等のエネルギー生成後の副産物を深地層下の岩盤内に隔離し，長期に渡りその性能を保証するためには，対象となる岩盤の水理学特性を詳細に把握することが必要不可欠である．特に，低透水性岩石を有する不連続性岩盤では，流体の流れは不連続面で支配的となるため，不連続面内の流体の流動特性を時間的かつ空間的に把握することは非常に重要となる．本研究では，作用応力・温度に依存する鉱物の溶解現象を記述するモデルを用いて，花崗岩不連続面の透水性の経時変化を定量的に評価した．また，拘束圧・温度を制御した花崗岩不連続面の透水試験結果と比較することにより，モデルの妥当性を検討した．
空気注入による地盤不飽和化の現場実験とそのモニタリング
岡村未対, 武林昌哉, 西田克司, 藤井直, 神宮司元治, 今里武彦, 安原英明, 中川恵美子
土木学会論文集Ｃ 65 3 756 - 766 公益社団法人土木学会 2009年
近年，地盤に空気を直接注入するなどして地盤を不飽和化する液状化対策工法が検討されており，既存工法に比べて格段に安価で既設構造物直下にも適用ができる工法として実用化が期待されている．本報告は，空気注入により地盤が不飽和化されることを実証し，不飽和化された領域を特定する技術の適用性を検討することを目的として行われた現場実験について述べるものである．実験ではGL.-6mに設置した注入口から空気を地盤に注入したたところ，空気流量は注入圧力と共に概ね直線的に増加した．比抵抗トモグラフィーとFDRプローブによる測定の結果，注入地点を中心に直径3∼4m程度の領域が不飽和化されたことが確認され，測定された飽和度はその後採取した凍結サンプリング試料の飽和度と良い対応を示した．
EXPERIMENTS AND PREDICTIONS OF SOIL DESATURATION BY AIR-INJECTION TECHNIQUE AND THE IMPLICATIONS MEDIATED BY MULTIPHASE FLOW SIMULATION
Hideaki Yasuhara, Mitsu Okamura, Yoshinori Kochi
SOILS AND FOUNDATIONS 48 6 791 - 804 2008年12月研究論文（学術雑誌）
Measures preventing an earth quake-induced soil liquefaction are of significant importance to mitigate the liquefaction hazards. An air-injection technique may be a simple, inexpensive method - this leads the saturated soils to the desaturated by injecting pressurized air, resulting in a higher liquefaction strength and lower susceptibility. The objective of this study is to investigate the evolution of desaturation process during air injection into saturated soil deposits and verify the validity of a multiphase flow simulator if it is capable of being applied for predicting the process as well as the distribution of degree of saturation after the air injection ceased. In this study simplified model tests that simulate the air injection into saturated soils using air-injection probes, are conducted using two different sizes of soil containers. The experiments using the small container are aimed to examine the nominal rates and magnitudes of the soil desaturation driven by air injection, whilst those with the large container are performed to obtain not only the rates and magnitudes but also the distributions of the desaturated zones within the soil. The results obtained indicate, although clearly depending on the physical properties of targeted soils, that the evolution of desaturation is strongly controlled by the air pressures injected and the soil permeabilities. Numerical analyses are also conducted using a multiphase flow simulator to describe the evolution of the soil desaturation, and to examine the applicability of,the model as a prediction toot enabling an evolution of desaturation in situ to be followed with time and space. Predictions show a relatively good agreement with the experimental measurements regarding the rates, magnitudes, and distribution of desaturation specifically for the small-container experiments although predictions of desaturated domain slightly overestimate the measurements for the large-container experiments. Thus, this study indicates that the numerical model described is applicable to field problems when the soil properties in terms of flow transport are well-constrained.
Compaction of a rock fracture moderated by competing roles of stress corrosion and pressure solution
Hideaki Yasuhara, Derek Elsworth
PURE AND APPLIED GEOPHYSICS 165 7 1289 - 1306 2008年07月 [査読有り]
研究論文（学術雑誌）
Unusually rapid closure of stressed fractures, observed in the initial stages of loading and at low temperatures, is examined using models for subcritical crack growth and pressure solution. The model for stress corrosion examines tensile stress concentrations induced at the Hertzian contact of propping fracture asperities, and mediates fracture growth according to a kinetic rate law. Conversely, pressure solution is described by the rate-limiting process of dissolution, resulting from the elevated stresses realized at the propping asperity contact. Both models are capable of following the observed compaction of fractures in novaculite. However, closure rates predicted for stress corrosion cracking are orders of magnitudes faster than those predicted for pressure dissolution. For consistent kinetic parameters, predictions from stress corrosion better replicate experimental observations, especially in the short-term and at low temperature when mechanical effects are anticipated to dominate. Rates and magnitudes of both stress corrosion and pressure solution are dependent on stresses exerted over propping asperities. Rates of closure due to stress corrosion cracking are shown to be always higher than for pressure solution, except where stress corrosion ceases as contact areas grow, and local stresses drop below an activation threshold. A simple rate law is apparent for the progress of fracture closure, defined in terms of a constant and an exponent applied to the test duration. For current experimental observations, this rate law is shown to replicate early progress data, and shows promise to define the evolution of transport properties of fractures over extended durations.
Modeling the kinetics of silica nanocolloid formation and precipitation in geologically relevant aqueous solutions
Christine F. Conrad, Gary A. Icopini, Hideaki Yasuhara, Joel Z. Bandstra, Susan L. Brantley, Peter J. Heaney
GEOCHIMICA ET COSMOCHIMICA ACTA 71 3 531 - 542 2007年02月 [査読有り]
研究論文（学術雑誌）
The kinetics of the formation and precipitation of nanocolloidal silica from geologically relevant aqueous solutions is investigated. Changes in monomeric (SiO2(mono)), nanocolloidal (SiO2(nano)) and precipitated silica (SiO2(ppt)) concentrations in aqueous solutions from pH 3 to 7, ionic strengths (IS) of 0.01 and 0.24 molal, and initial SiO2 concentrations of 20.8, 12.5 and 4.2 mmolal (reported in [Icopini, G.A., Brantley, S.L., Heaney, P.J., 2005. Kinetics of silica oligomerization and nanocolloid formation as a function of pH and ionic strength at 25 degrees C. Geochim. Cosmochim. Acta 69(2), 293-303.]) were fit using two kinetic models. The first model, termed the concentration model, is taken from Icopini et al. (2005) and assumes that the rate of change of SiO2(mono) as a function of time has a fourth-order dependence on the concentration of SiO2(mono) in solution. The second model, termed the supersaturation model, incorporates the equilibrium concentration of amorphous silica and predicts that polymerization will be a function of the degree of silica supersaturation in solution with respect to amorphous silica. While both models generally predicted similar rate constants for a given set of experimental conditions, the supersaturation model described the long-term equilibrium behavior of the SiO2(mono) fraction more accurately, resulting in significantly better fits of the monomeric data. No difference was seen between the model fits of the nanocolloidal silica fraction. At lower pH values (3-4), a metastable equilibrium was observed between SiO2(mono) and SiO2(nano). This equilibrium SiO2(mono) concentration was found to be 6 mmolal, or three times the reported solubility of bulk amorphous silica under the experimental conditions studied and corresponds to the predicted solubility of amorphous silica colloids approximately 3 nm in diameter. Atomic force microscopy was used to determine the average size of the primary nanocolloidal particles to be similar to 3 nm, which is in direct agreement with the solubility calculations. Larger aggregates of the primary nanocolloids were also observed to range in size from 30 to 40 nm. This work provides the first kinetic models describing the formation and evolution of nanocolloidal silica in environmentally relevant aqueous solutions. Results indicate that nanocolloidal silica is an important species at low pH and neutral pH at low ionic strengths and may play a more important role in geochemical cycles in natural aqueous systems than previously considered. (c) 2006 Elsevier Inc. All rights reserved.
温度・応力に依存する化学溶解・沈殿現象を考慮した珪質岩石の透水性経時評価
安原英明, 木下尚樹, 操上広志, 中島伸一郎, 岸田潔
土木学会論文集 C 63 4 1091-1100 (J-STAGE) - 1100 Japan Society of Civil Engineers 2007年
高レベル放射性廃棄物処分坑道近傍では，廃棄体からの発熱により化学作用が活発化し，岩盤の力学 · 水理学特性に大きな影響を及ぼすことが考えられる．本論文では，圧力溶解現象を考慮した概念モデルを用いて，熱 · 水 · 応力下における化学作用を定量化し，珪質岩石の透水性評価を行った．特に，珪質岩石の構成主鉱物である石英，クリストバライト，アモルファスシリカの溶解 · 沈殿特性に着目し，深地層下における圧力，廃棄体からの発熱作用を考慮し，透水特性の変化を定量的に評価した．その結果，90 °Cの温度条件下で時間と共に透水性が低下する傾向が得られた．また，クリストバライト，アモルファスシリカを多く有する珪質岩石は，石英系岩石よりも透水性の変化がより顕著となることが確認された．
Spontaneous switching between permeability enhancement and degradation in fractures in carbonate: Lumped parameter representation of mechanically- and chemically-mediated dissolution
Hide Yasuhara, Derek Elsworth, Amir Polak, Jishan Liu, Avrami Grader, Phillip Halleck
TRANSPORT IN POROUS MEDIA 65 3 385 - 409 2006年12月研究論文（学術雑誌）
Principal mechanical and chemical processes contributing to the observed spontaneous switching from net decrease in permeability to net increase in a fracture in carbonate are examined. The evolution of permeability, and related fracture aperture, is represented through a lumped parameter model. The significant processes of pressure solution beneath bridging asperities, transport of dissolved mass to the fracture void, and subsequent precipitation or dissolution within the fracture void enable the principal characteristics of observed behavior to be followed. The evolution of dissolved mass concentration in the pore fluid is followed for arbitrary applied stress, temperature, and pH conditions, with appropriate feedback to the evolution of fracture permeability. Comparisons with experimental measurements in limestone (Polak et al., 2004, Water Resour. Res. Vol. 40, W03502, doi: 10.1029/2003GL017575) show satisfactory agreement for the evolution of fracture aperture and to a lesser degree in calcium concentrations in the effluent pore fluid. Importantly, the spontaneous switching in permeability change, from aperture reducing to aperture increasing, with no change in environmental conditions, is replicated without the need for an ad hoc trigger. Although this switch is accurately replicated, the lumped parameter model is incapable of replicating the rapid observed growth in permeability that directly follows. This inability results from the assumed form of the lumped asperity model, that is incapable of representing the spatially distributed change in aperture that is seen to occur within the fracture. Despite this inconsistency, the model is shown capable of representing the principal behaviors evident in the response.
Short-timescale chemo-mechanical effects and their influence on the transport properties of fractured rock
Derek Elsworth, Hideaki Yasuhara
PURE AND APPLIED GEOPHYSICS 163 10 2051 - 2070 2006年10月 [査読有り]
研究論文（学術雑誌）
Anomalous changes in permeability are reported in fractures circulated by fluids undersaturated with respect to the mineral host. Under net dissolution and net removal of mineral mass, fractures may alternately gape or seal, depending on the prevailing mechanical and chemical conditions. The influence on transport properties is observed to be large, rapid, and irreversible: Permeabilities may change by two orders of magnitude in a month, and the direction of permeability change may switch spontaneously, for no apparent change in environmental forcing. These behaviors are apparent in continuous circulation experiments conducted on fractures in novaculite and limestone, intermittently imaged by X-ray CT. In novaculite, permeability reduces by two orders of magnitude as silica is net removed from the sample. Surprisingly, these changes can occur at modest temperatures (similar to 80 degrees C) and stresses (similar to 3.5 MPa), where compaction progresses as temperatures are incremented. Isothermal (similar to 20 degrees C) circulation tests in limestone show similar compaction driven by pressure solution. Where circulation remains undersaturated in Ca, the change in permeability spontaneously switches from net reduction to net increase as a wormhole forms. The surprising magnitude and rapidity of these changes are investigated in the context of the competition between stress- and chemistry-mediated effects.
A numerical model simulating reactive transport and evolution of fracture permeability
Hideaki Yasuhara, Derek Elsworth
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS 30 10 1039 - 1062 2006年08月 [査読有り]
研究論文（学術雑誌）
A numerical model is presented to describe the evolution of fracture aperture (and related permeability) mediated by the competing chemical processes of pressure solution and free-face dissolution/precipitation; pressure (dis)solution and precipitation effect net-reduction in aperture and free-face dissolution effects net-increase. These processes are incorporated to examine coupled thermo-hydro-mechano-chemo responses during a flow-through experiment, and applied to reckon the effect of forced fluid injection within rock fractures at geothermal and petroleum sites. The model accommodates advection-dominant transport systems by employing the Lagrangian-Eulerian method. This enables changes in aperture and solute concentration within a fracture to be followed with time for arbitrary driving effective stresses, fluid and rock temperatures, and fluid flow rates. This allows a systematic evaluation of evolving linked mechanical and chemical processes. Changes in fracture aperture and solute concentration tracked within a well-constrained flow-through test completed on a natural fracture in novaculite (Earth Planet. Sci. Lett. 2006, in press) are compared with the distributed parameter model. These results show relatively good agreement, excepting an enigmatic abrupt reduction in fracture aperture in the early experimental period, suggesting that other mechanisms such as mechanical creep and clogging induced by unanticipated local precipitation need to be quantified and incorporated. The model is applied to examine the evolution in fracture permeability for different inlet conditions, including localized (rather than distributed) injection. Predictions show the evolution of preferential flow paths driven by dissolution, and also define the sense of permeability evolution at field scale. Copyright (C) 2006 John Wiley & Sons, Ltd.
Evolution of fracture permeability through fluid-rock reaction under hydrothermal conditions
H Yasuhara, A Polak, Y Mitani, AS Grader, PM Halleck, D Elsworth
EARTH AND PLANETARY SCIENCE LETTERS 244 1-2 186 - 200 2006年04月研究論文（学術雑誌）
We report flow-through experiments on a natural fracture in novaculite under moderate effective stresses (similar to 1.4 Mpa) and temperatures (20-120 degrees C) to examine the effect on flow and transport characteristics. The efflux of fluid and dissolved minerals were measured throughout the 3150-h experiment. After the experiment the fracture was imaged by X-ray CT, impregnated with Wood's metal, and a cast recovered of the Wood's metal-filled fracture. These measurements constrain the evolution of fracture structure, and the change in permeability that resulted from stress- and temperature-dependent dissolution at both propping asperities and fracture void surfaces. During the first 1500 h, the aperture of one fracture decreased from 18.5 to 7.5 mu m, when it was loaded with constant effective stress of 1.4 MPa, at room temperature, and a flow rate decreasing with time from 1 to 0.0625 mL/min. This reduction is attributed to the removal of mineral mass from bridging asperities. After 1500 h the fracture aperture increased, ultimately reaching 13 pm. Apparently the dominant dissolution process switched from prop removal to etching of the void surfaces. We used X-ray CT images, digital radiographs, and fracture casts as independent methods to constrain the resulting architecture of the evolved fracture porosity, and developed a simple process-based model to examine the relative roles of asperity removal and free-face dissolution. The comparison of the model with the measurements identifies the relative importance of mass removal at fracture faces and at propping asperities. The experiments underscore the importance of dissolution in determining the sense, the rates and the magnitude of permeability-enhancement within rock fractures stimulated by chemical permeants in geothermal and petroleum reservoirs, and to a lesser degree under natural conditions pushed far-from-equilibrium. (c) 2006 Elsevier B.V. All rights reserved.
A fully-coupled hydrological-mechanical-chemical model for fracture sealing and preferential opening
JS Liu, JC Sheng, A Polak, D Elsworth, H Yasuhara, A Grader
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 43 1 23 - 36 2006年01月研究論文（学術雑誌）
A fully coupled hydrological-mechanical-chemical (HMC) model is developed and applied to explain enigmatic spontaneous changes in permeability that develop within a fracture in limestone under simulated in situ conditions (Water Resour Res 2004;40:W03502). The water flow-through test was concurrently monitored for water and dissolved mineral mass efflux and periodically imaged by X-ray CT to provide redundant constraints on fracture evolution by dissolution and precipitation. The resulting data, exhibiting a spontaneous switch between permeability-decreasing, and permeability-increasing, are evaluated using the HMC model. This model represents these two distinct behaviors: apertures first reduce, under presumed net dissolution, and then preferentially open as net dissolution is even more positively apparent. In the model, dissolution mechanisms within the fracture can be switched from mixed-mode (a combination of pressure dissolution and free-face dissolution) to single mode (pressure dissolution or free-face dissolution). This allows both permeability reduction as mineral mass is net removed from contacting asperities, and permeability enhancement as free-face dissolution localizes along a solution channel, to be accommodated and quantified. The model successfully replicates experimental measurements in limestone. (c) 2005 Elsevier Ltd. All rights reserved.
Evolution of fracture permeability through reactive flow at elevated temperatures
Hideaki Yasuhara, Amir Polak, Yasuhiro Mitani, Avrami Grader, Phillip Halleck, Derek Elsworth
Transactions - Geothermal Resources Council 29 437 - 441 2005年12月
Flow-through experiments are conducted on a natural fracture in novaculite at a constant effective stress of 1.38 MPa and at staged temperatures of 20, 40, 80, and 120°C. Fluid and mineral effluxes are measured throughout the 3150-hr experiment, together with post-experiment imaging by X-ray CT and destructive fracture-casting by Wood's metal impregnation. These measurements are used to constrain the evolution of dissolution-driven changes in fracture structure, and related permeability under hydrothermal conditions. At 20°C the fracture aperture monotonically decreases from an initial aperture of 18.5 μm to 7.5 μm during the first 1494 hrs. This reduction is attributed to removal of mineral mass from bridging asperities. Subsequently, fracture aperture increases to 13 μm and is interpreted as a switching of dominant dissolution processes to free-face etching of the fracture void surfaces. The resulting rate of gaping increases with an increase in temperature. Post-experiment imaging by X-ray CT and by using the fracture cast independently constrains the resulting architecture of the evolved fracture porosity. No localized flow channel is apparent, despite the evolving hydraulic response which is suggestive of an evolving dissolution channel.
Thermo-Hydro-Mechano-Chemical Couplings that Define the Evolution of Permeability in Rock Fractures
安原英明
the Pennsylvania State University 2005年08月 [査読有り]
学位論文（博士）
Fault zone restrengthening and frictional healing: The role of pressure solution
Hideaki Yasuhara, Chris Marone, Derek Elsworth
Journal of Geophysical Research B: Solid Earth 110 1 - 11 2005年06月
Laboratory and field observations note the significant role of strength recovery (healing) on faults during interseismic periods and implicate pressure solution as a plausible mechanism. Plausible rates for pressure solution to activate, and the magnitudes of ultimate strength gain, are examined through slide-hold-slide experiments using simulated quartz gouge. Experiments are conducted on fine-grained (110 μm) granular silica gouge, saturated with deionized water, confined under constant normal stress of 5 MPa and at modest temperatures of 20 and 65°C, and sheared at a maximum rate of 20 μm/s. Data at 20°C show a log linear relation between strength gain and the duration of holding periods, whereas the higher temperature observations indicate higher healing rates than the log linear dependencies; these are apparent for hold times greater than ∼1000 s. This behavior is attributed to the growth and welding of grain contact areas, mediated by pressure solution. The physical dependencies of this behavior are investigated through a mechanistic model incorporating the serial processes of grain contact dissolution, grain boundary diffusion, and precipitation at the rim of contacts. We use the model to predict strength gain for arbitrary conditions of mean stress, fluid pressure, and temperature. The strength gain predicted under the experimental conditions (σeff = 5 MPa and T = 65°C) underestimates experimental measurements for hold periods of less than ∼1000 s where other frictional mechanisms contribute to strength gain. Beyond this threshold, laboratory observations resemble the trend in the prediction by our mechanistic model, implicating that pressure solution is likely the dominant mechanism for strength gain. The model is applied to the long-term prediction of healing behavior in quartzite fault zones. Predictions show that both rates and magnitudes of gain in contact area increase with an increase in applied stresses and temperatures and that fault healing aided by pressure solution should reach completion within recurrence interval durations ranging from <1 to ∼104 years, depending on applied stresses, temperatures, and reaction rates. Copyright 2005 by the American Geophysical Union.
Evolution of permeability in a natural fracture: Significant role of pressure solution
Hideaki Yasuhara, Derek Elsworth, Amir Polak
Journal of Geophysical Research B: Solid Earth 109 2004年03月
A mechanistic model is presented to describe closure of a fracture mediated by pressure solution; closure controls permeability reduction and incorporates the serial processes of dissolution at contacting asperities, interfacial diffusion, and precipitation at the free face of fractures. These processes progress over a representative contacting asperity and define compaction at the macroscopic level, together with evolving changes in solute concentration for arbitrarily open or closed systems for prescribed ranges of driving effective stresses, equilibrium fluid and rock temperatures, and fluid flow rates. Measured fracture surface profiles are applied to define simple relations between fracture wall contact area ratio and fracture aperture that represents the irreversible alteration of the fracture surface geometry as compaction proceeds. Comparisons with experimental measurements of aperture reduction conducted on a natural fracture in novaculite [Polak et al., 2003] show good agreement if the unknown magnitude of microscopic asperity contact area is increased over the nominal fracture contact area. Predictions of silica concentration slightly underestimate the experimental results even for elevated microscopic contact areas and may result from the unaccounted contribution of free face dissolution. For the modest temperatures (20-150°C) and short duration (900 hours) of the test, pressure solution is demonstrated to be the dominant mechanism contributing to both compaction and permeability reduction, despite net dissolution and removal of mineral mass. Pressure solution results in an 80% reduction in fracture aperture from 12 μm, in contrast to a ∼ 10 nm contribution by precipitation, even for the case of a closed system. For the considered dissolution-dominated system, fracture closure rates are shown to scale roughly linearly with stress increase and exponentially with temperature increase, taking between days and decades for closure to reach completion. Copyright 2004 by the American Geophysical Union.
A mechanistic model for compaction of granular aggregates moderated by pressure solution
Hideaki Yasuhara, Derek Elsworth, Amir Polak
Journal of Geophysical Research: Solid Earth 108 2003年11月
A model is presented for the compaction of granular aggregates that accommodates the serial processes of grain-contact dissolution, grain-boundary diffusion, and precipitation at the pore wall. The progress of compaction and the evolution of the mass concentration of the pore fluids may be followed with time, for arbitrary mean stress, fluid pressure, and temperature conditions, for hydraulically open or closed systems, and accommodating arbitrary switching in dominant processes, from dissolution, to diffusion, to precipitation. Hindcast comparisons for compaction of quartz sands [Elias and Hajash, 1992] show excellent agreement for rates of change of porosity, the asymptotic long-term porosity, and for the development of silica concentrations in the pore fluid with time. Predictions may be extended to hydraulically open systems where flushing by meteoric fluids affects the compaction response. For basins at depths to a few kilometers, at effective stresses of 35 MPa, and temperatures in the range 75°-300°C, rates of porosity reduction and ultimate magnitudes of porosity reduction increase with increased temperature. Ultimate porosities asymptote to the order of 15% (300°C) to 25% (75°C) at the completion of dissolution-mediated compaction and durations are accelerated from a few centuries to a fraction of a year as the temperature is increased. Where the system is hydraulically open, flushing elevates the final porosity, has little effect on evolving strain in these precipitation-controlled systems, and depresses pore fluid concentrations. These effects are greatest at lower temperatures. Copyright 2003 by the American Geophysical Union.
Permeability reduction of a natural fracture under net dissolution by hydrothermal fluids
A. Polak, D. Elsworth, H. Yasuhara, A. S. Grader, P. M. Halleck
Geophysical Research Letters 30 2003年10月
Flow-through tests are completed on a natural fracture in novaculite at temperatures of 20°C, 80°C, 120°C, and 150°C. Measurements of fluid and dissolved mass fluxes, and concurrent X-ray CT imaging, are used to constrain the progress of mineral dissolution and its effect on transport properties. Under constant effective stress, fracture permeability decreases monotonically with an increase in temperature. Increases in temperature cause closure of the fracture, although each increment in temperature causes a successively smaller effect. The initial differential fluid pressure-drop across the fracture increases by two orders of magnitude through the 900 h duration of the test, consistent with a reduction of an equivalent hydraulic aperture by a factor of five. Both the magnitude and rate of aperture reduction is consistent with the dissolution of stressed asperities in contact, as confirmed by the hydraulic and mass efflux data. These observations are confirmed by CT imaging, resolved to 35 microns, and define the potentially substantial influence that benign changes in environmental conditions of stress, temperature, and chemistry may exert on transport properties. © 2003 by the American Geophysical Union.
Experimental study on the dilatancy behavior of single joints under constant tau/sigma loading conditions
K Kishida, H Yasuhara, T Adachi
PACIFIC ROCKS 2000: ROCK AROUND THE RIM 651 - 658 2000年 [査読有り]
研究論文（国際会議プロシーディングス）
The mechanical behavior of jointed rock masses is strongly affected by the mechanical behavior of rock joints. In turn, the mechanical behavior of rock joints is dependent upon the relationship between the orientation of the joints and the direction of the stress (load) in the field. Thus, it is considered that the mechanical behavior of rock joints consists of three parameters, namely, normal stiffness k(pi), shear stiffness k(s), and the dilatancy property. The goals of this research work are to determine these three parameters, to develop a constitutive law for rock joints, and to apply the field works of rock engineering. In order to achieve the above goal, constant pi/sigma loading tests are carried out. The dilatancy properties of rock joints based on the results of the constant pi/sigma loading tests are discussed in this paper, and a constitutive model for the mechanical behavior of rock joints is estimated. Comparing the theoretical analyses with the experimental results, the constitutive model is applied to the numerical simulation.
Experimental study on the mechanical behavior of single joint under a constant tau/sigma loading condition and its application to mechanical modeling
H Yasuhara, K Kishida, H Fujii, T Adachi
ROCK MECHANICS FOR INDUSTRY, VOLS 1 AND 2 415 - 421 1999年 [査読有り]
研究論文（国際会議プロシーディングス）
Although the joint element method can be applied to numerical analyses of jointed rock masses, the effort in data preparation involving the joint parameters, the constitutive law, and the number of joints is increased. To overcome this difficulty, the equivalent continuous model is applied-instead of the joint element method. In this study, focus is placed on the mechanical parameters, normal stiffness k(n) and shear stiffness k(s). The relationship of k(n) and k(s) (Goodman 1984) is measured in this study by constant tau/sigma loading tests. Then, the results are used to determine the material constants of the equivalent continuous model.
書籍

書籍等出版物: 岩盤工学分野における熱・水・応力・化学連成解析─エネルギー問題に対する連成解析の果たすべき役割─
(範囲:数式のない土木の数値解析セミナー［第16回］)
土木学会誌 2018年04月
月刊愛媛ジャーナル
安原英明 (範囲:熱・水・応力・化学の相互作用が岩盤へ及ぼす影響：THMC連成シミュレータの開発)
2009年

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The 3rd International Conference on Global Issue for infrastructure, environment & Socio-economic development（Hasanuddin University, Indonesia，オンライン講演） 2020年11月口頭発表（基調）
Prediction of permeability evolution in granite under the coupled THMC interactions with pH alteration [通常講演]
S. Ogata, H. Yasuhara, N. Kinoshita, T. Inui, S. Mishima, K. Kishida
2nd International Conference on Coupled Processes in Fractured Geological Media: Observations, Modeling (CouFrac2020), Online & Seoul National University 2020年11月口頭発表（一般）
Coupled THMC processes that regulate flow and transport behavior in fractured rocks [招待講演]
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The International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application (CouFrac2020)（Seoul National University，オンライン講演） 2020年11月シンポジウム・ワークショップパネル（指名）
Soil Improvement Technique for Liquefaction Prevention [招待講演]
Hideaki Yasuhara
The 1st International Seminar on Civil and Environmental Engineering (ISCEE) 2020（IPB University, Indonesia，オンライン講演） 2020年11月口頭発表（基調）
Efficacy of organic additive in EICP technique for soil improvement [通常講演]
Heny Sulistiawati Baiq, Heriansyah Putra, Abdullah Almajed, Naoki Kinoshita, Hideaki Yasuhara
The 2020 World Congress on Advances in Civil and Environmental, Materials Research,Online 2020年08月口頭発表（一般）
Coupled THMC coupling simulation for estimating the long-term evolution of rock permeability depending on groundwater chemistry [通常講演]
Ogata, S, Yasuhara, H, Kinoshita, N, Kishida, K
54th US Symp. on Rock Mechs./Geomechs, Golden, Colorado,Online 2020年06月口頭発表（一般）
岩石中の透水流動 [招待講演]
安原英明
2019年度岩盤工学基礎講座（岩の力学連合会） 2020年02月公開講演，セミナー，チュートリアル，講習，講義等
鉱物分布・組成を考慮した数値解析モデルによる花崗岩の引張破壊挙動の予測 [通常講演]
伊澤正悟, 緒方奨, 安原英明, 木下尚樹, 岸田潔
第47回岩盤力学に関するシンポジウム 2020年01月口頭発表（一般）
Analysis of Surface Failure of Slopes using Slope Deformation Monitoring System Based on Inclinometers with LPWA [通常講演]
Aulia Dharma Putra, Hikaru Toda, Hideaki Yasuhara, Naoki Kinoshita
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月口頭発表（一般）
Short- and long-term permeability tests of a single rock fracture under coupled conditions [通常講演]
Chenlu Song, Hideaki Yasuhara, Shinichiro Nakashima, Kiyoshi Kishida
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月口頭発表（一般）
Preliminary experiments of hydraulic fracturing by developing the experimental apparatus [通常講演]
Kokoro Kajiwara, Hideaki Yasuhara, Naoki Kinoshita, Sho Ogata
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月ポスター発表
Simulations of flow-through experiments using the granite fractures by THMC coupled model considering pH dependence [通常講演]
Takeru Kumagai, Hideaki Yasuhara, Naoki Kinoshita, Sho Ogata
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月ポスター発表
Development of test apparatus using transient pulse method for rock permeability measurement [通常講演]
Kohya Sumimoto, Hideaki Yasuhara, Naoki Kinoshita
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月ポスター発表
Development of experimental apparatus for two-phase flow in rocks and preliminary results using Berea sandstone [通常講演]
Kentaro Ouchi, Hideaki Yasuhara, Naoki Kinoshita
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月ポスター発表
Development of multi-physics simulator by considering damage evolution due to mineral reactions in fractured rocks [通常講演]
Sho Ogata, Hideaki Yasuhara and Kiyoshi Kishida
The 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月口頭発表（一般）
Numerical Investigation for Modeling Lahendong Geothermal Field, North Sulawesi, Indonesia [通常講演]
Muhammad Qarinur, Hideaki Yasuhara, Naoki Kinoshita
he 5th ISRM Young Scholars’ Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future 2019年12月口頭発表（一般）
Examination of calcite precipitation using plant-derived urease enzyme for soil improvement
Heny Sulistiawati Baiq, Hideaki Yasuhara, Naoki Kinoshita, Heriansyah Putra
9th International Conference on Geotechnique, Construction Materials and Environment 2019年11月口頭発表（一般）
「災害大国」日本～平成30年7月豪雨を中心に～ [招待講演]
安原英明
令和元年度第42回現代教養講座 2019年10月公開講演，セミナー，チュートリアル，講習，講義等
THMC Couplings that Regulate Flow and Transport Behavior in Fractured Rocks [招待講演]
Hideaki Yasuhara
The 4th International Workshop on Rock Mechanics in Nuclear Waste Disposal 2019年09月公開講演，セミナー，チュートリアル，講習，講義等
Thermo-hydro-mechanical modeling to simulate Lahendong geothermal field [通常講演]
Muhammad Qarinur, Hideaki Yasuhara, Naoki Kinoshita
The 7th Indonesia International Geothermal Convention & Exhibition (IIGCE) 2019 2019年08月口頭発表（一般）
Thermal-hydraulic-mechanical-chemical Couplings that Define the Evolution of Flow and Transport Behavior in Fractured Rocks [招待講演]
Hideaki Yasuhara
Center for HLW Geological Disposal Seminar in KIGAM 2019年07月公開講演，セミナー，チュートリアル，講習，講義等
Coupled THMC analysis for predicting hydro-mechanical evolution in siliceous mudstone [通常講演]
Ogata, S, Yasuhara, H, Aoyagi, K, Kishida, K
53rd US Symp. on Rock Mechs./Geomechs 2019年06月口頭発表（一般）
Long-term permeability experiments of a single fracture in granite under thermal conditions and evaluation of the aperture distribution through microfocus X-ray CT [通常講演]
Song, C. L, Nakashima, S, Yasuhara, H, Iseki, K, Kishida, K
53rd US Symp. on Rock Mechs./Geomechs 2019年06月口頭発表（一般）
亀裂発生・進展を考慮したマルチフィジックスシミュレータの開発 [通常講演]
緒方奨, 安原英明, 岸田潔
第46回岩盤力学に関するシンポジウム 2019年01月口頭発表（一般）
Multi-physics modeling by incorporating damage theory for evaluating rock permeability change [通常講演]
Sho Ogata, Hideaki Yasuhara, Kiyoshi Kishida
The Thirty-first KKHTCNN Symposium on Civil Engineering 2018年11月口頭発表（一般）
Evaluation on the healing of single rock fracture with consideration of the critical state during slide-hold-slide process [通常講演]
Kosuke Matsumoto, Hideaki Yasuhara, Takao Yano, Kiyoshi Kishida
The Thirty-first KKHTCNN Symposium on Civil Engineering 2018年11月口頭発表（一般）
Permeability variation of granite single fracture in considering influence of temperature and stress confining period [通常講演]
Chenlu Song, Shinichiro Nakashima, Hideaki Yasuhara, Kiyoshi Kishida
The Thirty-first KKHTCNN Symposium on Civil Engineering 2018年11月口頭発表（一般）
Coupled THMC modelling by considering damage theory and pressure dissolution for predicting permeability change in fractured rocks [通常講演]
H.Yasuhara, S.Ogata, N.Kinoshita, K.Kishida
International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application 2018年11月口頭発表（一般）
Thermal-hydraulic-mechanical-chemical Couplings that Define the Evolution of Flow and Transport Behavior in Fractured Rocks [招待講演]
安原英明
10th Asian Rock Mechanics Symposium (2018 ARMS10), Singapore, 2018年10月口頭発表（招待・特別）
Estimation on Permeability of Granite Single Fracture with Cyclic Loading and Unloading Processes Under Various Thermal Conditions [通常講演]
Chenlu Song, Takao Yano, Shinichiro Nakashima, Hideaki Yasuhara, Kishida Kiyoshi
10th Asian Rock Mechanics Symposium (2018 ARMS10), Singapore 2018年10月口頭発表（一般）
Numerical Investigation for Estimation of Rock Temperature in Enhanced Geothermal System, Proc. The 6th Indonesia International Geothermal Convention & Exhibition [通常講演]
Muhammad Qarinur, Hideaki Yasuhara, Naoki Kinoshita
The 6th Indonesia International Geothermal Convention & Exhibition (IIGCE) 2018 2018年09月ポスター発表
Sustainability of Enzyme-Mediated Calcite Precipitation Method as an Environmental-Friendly Soil Improvement Technique [通常講演]
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita
The 2018 World Congress on Advances in Civil and Environmental, Materials Research 2018年08月口頭発表（一般）
Geochemically-regulated evolution of rock and sand properties under coupled conditions [招待講演]
安原英明
C-Best projec 2018年07月公開講演，セミナー，チュートリアル，講習，講義等
Coupled THMC modelling of single fractures in novaculite and granite [通常講演]
Bond, A.E, Chittenden, N, Fedors, R, Lang, P, McDermott, C, Neretnieks, I, Pan, P.Z, Sembera, J, Brusky, I, Wanatabe, N, Lu, R, Yasuhara, H
2nd International Discrete Fracture Network Engineering Conference 2018年06月口頭発表（一般）
Coupled THMC modeling by considering damage theory for predicting permeability change in fractured rocks [通常講演]
Ogata, S, Yasuhara, H, Kinoshita, N, Kishida, K
52nd US Symp. on Rock Mechs./Geomechs 2018年06月口頭発表（一般）
Dual porosity理論を考慮した連成シミュレータによる岩盤浸透流解析 [通常講演]
緒方奨, 安原英明, 岸田潔
第45回岩盤力学に関するシンポジウム講演集(CD-ROM) 2018年01月口頭発表（一般）
花崗岩不連続面における透水実験と鉱物溶解機構の検討 [通常講演]
廣惠なつ美, 安原英明, 木下尚樹
第45回岩盤力学に関するシンポジウム講演集(CD-ROM) 2018年01月口頭発表（一般）
岩石不連続面のSHS型一面せん断試験と速度・状態を考慮した応力回復現象の評価 [通常講演]
松本航佑, 矢野隆夫, 安原英明, 岸田潔
第45回岩盤力学に関するシンポジウム講演集(CD-ROM) 2018年01月口頭発表（一般）
NGH貯蔵を想定した地下空洞の変形挙動評価 [通常講演]
SON Wonjun, 安原英明, 木下尚樹
第45回岩盤力学に関するシンポジウム講演集(CD-ROM) 2018年01月口頭発表（一般）
岩石不連続面における圧力溶解を考慮した熱・水・応力・化学連成解析モデルの開発とその性能評価 [通常講演]
緒方奨, 安原英明, 岸田潔
地盤工学研究発表会発表講演集(CD-ROM) 2018年口頭発表（一般）
Coupled thermal-hydraulic-mechanical-chemical modeling for predicting the evolution of permeability on fractured rocks [通常講演]
Sho Ogata, Hideaki Yasuhara, Kiyoshi Kishida
The Thirtieth KKHTCNN Symposium on Civil Engineering 2017年11月口頭発表（一般）
Structural Weakening and Recovery of Soft Rocks [通常講演]
Nguyen Pham, Quang Vu, Mamoru Kikumoto, Hideaki Yasuhara, Kiyoshi Kishida
The Thirtieth KKHTCNN Symposium on Civil Engineering 2017年11月口頭発表（一般）
Simulated mineral trapping of CO2 geo-sequestration: Evolution of physical properties [招待講演]
安原英明
The 4th International Symposium on Unconventional Geomechanics 2017年10月公開講演，セミナー，チュートリアル，講習，講義等
Dual porosity理論を用いた熱・水・応力・化学連成解析モデルの開発と不連続性岩盤への適用 [通常講演]
緒方奨, 安原英明, 岸潔
第38回西日本岩盤工学シンポジウム 2017年09月口頭発表（一般）
シェールオイル・ガス開発時のプロパント処理亀裂の長期透水挙動評価 [通常講演]
安原英明
岩谷直治記念財団研究報告書 2017年08月公開講演，セミナー，チュートリアル，講習，講義等
熱・水理・力学・化学連成現象と地盤・岩盤工学の諸課題 [招待講演]
安原英明
地盤工学とリスク共生II－若手が考える地盤工学の姿 2017年07月公開講演，セミナー，チュートリアル，講習，講義等
Evaluation of cutoff time on slide-hold-slide process of single rock joint in consideration of the heating influence [通常講演]
Kishida., K, Matsumoto, K, Yano, ST, Nakashima, S, Yasuhara, H
51st US Symp. on Rock Mechs./Geomechs, San Francisco, CA 2017年06月口頭発表（一般）
Numerical modeling of coupled THMC processes for predicting fluid flow and transport behavior within fractured rocks [通常講演]
Ogata, S, Kinoshita, N, Yasuhara, H, Kishida, K
51st US Symp. on Rock Mechs./Geomechs, San Francisco, CA 2017年06月口頭発表（一般）
Observation and quantification of fracture aperture in granite core using X-ray tomography and edge detection technique [通常講演]
Nakashima, S, Sakamoto, T, Yasuhara, H, Kishida, K
51st US Symp. on Rock Mechs./Geomechs, San Francisco, CA 2017年06月口頭発表（一般）
Geochemically-regulated evolution of rock permeability and mechanical properties under stressed and heated conditions [通常講演]
安原英明
China National Nuclear Corporation 2017年03月公開講演，セミナー，チュートリアル，講習，講義等
Geochemically-regulated evolution of rock permeability and mechanical properties under stressed and heated conditions [招待講演]
安原英明
Chinese Academy of Sciences 2017年03月公開講演，セミナー，チュートリアル，講習，講義等
持続載荷せん断試験による岩石不連続面の変形特性評価 [通常講演]
岡本哲徳, 安原英明, 木下尚樹
第14回岩の力学に関するシンポジウム 2017年01月口頭発表（一般）
圧力溶解と岩盤・地層処分：連成数値シミュレータを用いた天然バリアの長期透水特性評価 [通常講演]
緒方奨, 安原英明, 木下尚樹
第14回岩の力学に関するシンポジウム 2017年01月口頭発表（一般）
Estimation on SHS process strength recovery through rock specimen included artificial cutting plane [通常講演]
Shinji SAKAI, Takao YANO, Hideaki YASUHARA, Masato OHNO, Kiyoshi KISHIDA
The Twenty-Ninth KKHTCNN Symposium on Civil Engineering 2016年12月口頭発表（一般）
連成場における長期透水試験と連成数値シミュレータによる天然バリアの長期透水・物質輸送解析 [招待講演]
安原英明
地層処分における岩盤力学研究セミナー 2016年10月公開講演，セミナー，チュートリアル，講習，講義等
Enzyme-mediated carbonate precipitation (EMCP) for soil improvement: the effect of magnesium substitution [通常講演]
Hideaki Yasuhara, Heriansyah Putra, Naoki Kinoshita
Proc. The 2016 World Congress on Advances in Civil and Environmental, Materials Research (ASEM16) 2016年08月口頭発表（一般）
Predictions of rock permeability by THMC model considering pressure solution [通常講演]
Yasuhara, H, Kinoshita, N, Kishida, K
Proc. 50th US Symp. on Rock Mechs./Geomechs, Houston, TX 2016年06月口頭発表（一般）
Critical State Modeling of Sedimentary Rock Incorporating Healing and Decay of Rock Structure [通常講演]
Vu, P. Q. N, Kikumoto, M, Yasuhara, H, Kishida, K
Proc. 50th US Symp. on Rock Mechs./Geomechs, Houston, TX 2016年06月口頭発表（一般）
Permeability Experiment in a Single Granite Fracture under Different Stress, Temperature, and pH Conditions [通常講演]
Hideaki Yasuhara, Naoki Kinoshita, Dae-Sung Cheon, Kiyoshi Kishida
Proc. 2016 Korea-Japan Symposium on Rock Mechanics Engineering, Daejeon, Korea 2016年05月口頭発表（一般）
Evaluation of long-term permeability change of rocks by THMC numerical simulation model [通常講演]
Sho Ogata, Hideaki Yasuhara, Naoki Kinoshita
第44回岩盤力学に関するシンポジウム講演集 2016年01月口頭発表（一般）
EVALUATION OF PERMEABILITY CHANGE IN PROPPANTS AND PROPPANT TREATED ROCK FRACTURE [通常講演]
Takumi SUGANO, Hideaki YASUHARA, Naoki KINOSHITA, Dae-sung LEE
第44回岩盤力学に関するシンポジウム講演集 2016年01月口頭発表（一般）
EVALUATION OF STRENGTH RECOVERY ON ARTIFICAL CUTTING PLANE THROUGH SHS TYPE TRIAXIAL COMPRESSION TESTS USING TUFF [通常講演]
Kishida, KIYOSHI, Shinji SAKAI, Takao YANO, Hideaki YASUHARA, Masato OHNO, Mamoru KIKUMOTO
第44回岩盤力学に関するシンポジウム講演集 2016年01月口頭発表（一般）
熱・水・応力・化学連成解析モデルによる岩盤の長期透水特性評価 [通常講演]
緒方奨, 安原英明, 木下尚樹
第44回岩盤力学に関するシンポジウム講演集 2016年口頭発表（一般）
プロパント処理した岩盤亀裂の透水特性評価 [通常講演]
菅野巧, 安原英明, 木下尚樹, Dae-Sung LEE
第44回岩盤力学に関するシンポジウム講演集 2016年口頭発表（一般）
凝灰岩を用いたSHS型三軸せん断試験におけるせん断面の有無が強度回復現象に与える影響 [通常講演]
岸田潔, 酒井慎二, 矢野隆夫, 安原英明, 大野正登, 菊本統
第44回岩盤力学に関するシンポジウム講演集 2016年口頭発表（一般）
Coupled THMC model to predict long-term evolution of rock permeability [通常講演]
Hideaki YASUHARA, Kiyoshi KISHIDA
Proc. The Twenty-Eight KKHTCNN Symposium on Civil Engineering 2015年11月口頭発表（一般）
Permeability of a single fracture in granite under the confining pressure and extraction of fracture structure using microfocus X-ray CT [通常講演]
Tomohiro ISHIKAWA, Hideki YASUHARA, Yosuke HIGO, Kiyoshi KISHIDA
Proc. The Twenty-Eight KKHTCNN Symposium on Civil Engineering 2015年11月口頭発表（一般）
Optimization of calcite precipitation as a soil improvement technique [通常講演]
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita, Debendra Neupane
Proc. the 2nd Makassar International Conference on Civil Engineering (MICCE 2015) 2015年08月口頭発表（一般）
Constraining key factors that control evolution of rock permeability under high temperature, stress, and pH conditions [招待講演]
安原英明
Energy Technology Innovation Seminar in KIGAM 2015年07月公開講演，セミナー，チュートリアル，講習，講義等
Measurements of fracture aperture in granite core using microfocus X-ray CT and fluid flow simulation [通常講演]
Kishida, K, Ishikawa, T, Higo, Y, Sawada, A, Yasuhara, H
Proc. 49th US Symp. on Rock Mechs./Geomechs 2015年06月口頭発表（一般）
CHEMICALLY- AND MECHANICALLY-DRIVEN ALTERATION OF PERMEABILITY IN FRACTURED ROCKS UNDER DIFFERENT STRESS, TEMPERATURE, AND PH CONDITIONS [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
Proc. the 13th International Congress of Rock Mechanics, ISRM Congress 2015 2015年05月口頭発表（一般）
Structural healing and decay of sedimentary soft rock under slide-hold-slide process and their constitutive description [通常講演]
Nguyen Pham, Quang VU, Mamoru KIKUMOTO, Masato OHNO, Hideaki YASUHARA, Kiyoshi KISHIDA
第43回岩盤力学に関するシンポジウム講演集 2015年口頭発表（一般）
Mechanical Behavior of Rock Joints with Various Kinds of Joint Surface Roughness under Cyclic Direct Shear Loading Conditions [通常講演]
Sumit MASKEY, Hideaki YASUHARA, Kiyoshi KISHIDA
第43回岩盤力学に関するシンポジウム講演集 2015年口頭発表（一般）
強アルカリ環境における花崗岩不連続面の透水試験 [通常講演]
前田健太, 安原英明, 木下尚樹
資源・素材2015（松山）講演集 2015年口頭発表（一般）
Evaluation of enzyme mediated calcite grouting as a possible soil improvement technique [通常講演]
D. Neupane, H. Yasuhara, N. Kinoshita
Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014 2015年01月口頭発表（一般）
This paper discusses the experimental and numerical work on Enzyme Mediated Calcite Precipitation, EMCP, technique along with the improved mechanical properties of sand achieved by employing this technique. The homogenous sand specimen having a diameter of 57 cm and a height of 60 cm is prepared inside a steel drum. Freshly prepared grout solution (urea-CaCl2 and urease) is injected at the centre of the sand specimen. Afterwards, the improved samples within the treated specimen is taken and subjected to the compressive strength tests. The calcite distribution throughout the specimen is also evaluated.A multi-component, fluid flow and geo-chemical transport simulator that can incorporate the precipitation reaction during the flow, is used to predict the calcite distribution. The experimental results are compared with the numerical predictions. The evaluated simulator can approximately predict the distribution of calcite within the sand specimen. The small amount of calcite precipitated within the soil mass appreciably improves the mechanical properties of sandy soil. The improved mechanical properties are enough to increase the resistance of soil against liquefaction. © 2015 Taylor & Francis Group, London.
持続載荷による岩石不連続面の変形挙動に及ぼす熱・水・応力の影響 [通常講演]
木下尚樹, 安原英明, 崎山久美子
岩盤力学に関するシンポジウム講演論文集 2014年01月口頭発表（一般）
CO₂地中貯留に起因する鉱物トラップが岩盤の力学・透水特性に与える影響 [通常講演]
柏木亮太, 安原英明, 木下尚樹
岩盤力学に関するシンポジウム講演論文集 2014年01月口頭発表（一般）
力学-化学連成数値モデルによるベレア砂岩透水性経時変化の再現解析 [通常講演]
伊藤文, 安原英明, 木下尚樹
岩盤力学に関するシンポジウム講演論文集 2014年01月口頭発表（一般）
凝灰岩の三軸せん断-保持-せん断試験と拘束圧による影響 [通常講演]
大野正登, 矢野隆夫, 安原英明
岩盤力学に関するシンポジウム講演論文集 2014年01月口頭発表（一般）
加温条件下でのラフネスを有する不連続面のSlide-Hold-Slide試験とヒーリング現象 [通常講演]
津田直弥, 矢野隆夫, 安原英明
岩盤力学に関するシンポジウム講演論文集 2014年01月口頭発表（一般）
OPTIMIZATION OF TREATMENT AREA OF ENZYME MEDIATED CALCITE CEMENTATION: A NOVEL SOIL IMPROVEMENT TECHNIQUE [通常講演]
Debendra Neupane, Hideaki Yasuhara, Naoki Kinoshita
Proc. Fourth International Conference on Geotechnique, Construction Materials and Environment 2014年口頭発表（一般）
Coupled THMC modelling of a single fracture in novaculite for DECOVALEX-2015 [通常講演]
Bond A.E, Chittenden N, Fedors, R, Lang P.S, McDermott C, Neretniecks I, Šembera J, Watanabe N, Yasuhara H
Proc. International Discrete Fracture Network Engineering Conference 2014年口頭発表（一般）
Evolution of Permeability in Granite Fracture under High pH Conditions [通常講演]
H. Yasuhara, N. Kinoshita, K. Maeta, S. Nakashima, K. Kishida
Proc. 8th Asian Rock Mechanics Symposium (2014 ARMS8) 2014年口頭発表（一般）
Discussion on friction factor of single rock joint under slide-hold-slide process in considering influence of thermal conditions [通常講演]
Naoya Tsuda, Hideaki Yasuhara, Takao Yano, Kiyoshi Kishida
Mechanics Symposium (2014 ARMS8) 2014年口頭発表（一般）
Mechanical Behavior of Rock Joints with Various Kinds of Joint Surface Roughness under Cyclic Direct Shear Loading Conditions [通常講演]
S. Maskey, H. Yasuhara, K. Kishida
Proc. 8th Asian Rock Mechanics Symposium (2014 ARMS8) 2014年口頭発表（一般）
Structural healing and decay of sedimentary soft rock in triaxial slide-hold-slide process and its modeling [通常講演]
Mamoru Kikumoto, Nguyen P. Q. Vu, Masato Ohno, Kiyoshi Kishida, Hideaki Yasuhara, Derek Elsworth
Proc. 8th Asian Rock Mechanics Symposium (2014 ARMS8) 2014年口頭発表（一般）
Time Dependency Friction Factor of Rock Single Fracture under Slide-Hold-Slide Direct Shear Experiments [通常講演]
Kishida, K, Tsuda, N, Yano, T, Yasuhara, H
Proc. 48th US Symp. on Rock Mechs 2014年口頭発表（一般）
熱環境における岩石不連続面の連続透水・せん断実験 [通常講演]
木下尚樹, 安原英明, 高橋学
資源・素材2014（熊本）講演集 2014年口頭発表（一般）
Evolution of mechanical and hydraulic properties in sandstone induced by mineral trapping [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
48th US Rock Mechanics / Geomechanics Symposium 2014 2014年01月口頭発表（一般）
Copyright (2014) ARMA, American Rock Mechanics Association In this study, evolution of mechanical and hydraulic properties in Berea sandstone with initial porosity of 20 % is examined quantitatively by replicating mineral trapping process within pore spaces. The artificially accelerated mineral trapping is achieved by injecting a grout, resulting in calcite precipitation. The amount of calcite precipitated can be controlled by changing the concentrations of the grout and the total injection volume. The preliminary experiments indicate that the change of the mechanical and hydraulic properties is significant even if the calcite amount is relatively small - The values of Young's modulus/permeability increase/decrease with increase of the calcite amount. Specifically, the permeability decreases by one order of magnitude as the initial porosity of 20 % reduces to 18 %. This intense decrease of permeability may not be able to be replicated by existing numerical models, although distribution of the calcite precipitated within rock samples should be adequately examined because uniform distribution may not be achieved.
Long-term observation of rock permeability under high pressure and temperature conditions and its microstructural interpretation [通常講演]
H. Yasuhara, N. Kinoshita, M. Takahashi, S. Nakashima, K. Kishida
47th US Rock Mechanics / Geomechanics Symposium 2013 2013年12月口頭発表（一般）
A series of long-term permeability experiments using Berea Sandstone and Horonobe Mudstone has been conducted so as to understand the evolution of rock permeability under stressed and temperature-elevated conditions. The well-controlled experiments are carried out at confining pressures of 3.0-15 MPa and temperatures of 20 or 25 and 90°C. Flow-through experiments are conducted regularly (i.e., 5 or 10 day interval) to examine the evolution of rock permeability throughout the experiments - it should be noted that each experiment is kept always more than 500 days. Effluent concentrations are also measured for the ten elements of Si, Al, K, Fe, Ca, Na, Mg, Ti, S, and Cl that are included mainly in the targeted rocks. Rock samples were prepared for a SEM-EDX and/or a micro-focus X-ray CT to observe its microstructure. The SEM-EDX observation revealed that mineral dissolution dominates over mineral precipitation, and the micro-focus X-ray CT observation shows a slight increase in pore volume for the sandstone sample that has experienced long-term confining pressure and temperature. Copyright 2013 ARMA, American Rock Mechanics Association.
Chemo-Mechano Coupling Processes Inducing Evolution of Rock Permeability under Hydrothermal and Stressed Conditions [招待講演]
Hideaki Yasuhara, Manabu TAKAHASHI, Kiyoshi Kishida, Shinichiro Nakashima
Eos Trans. AGU, Fall Meet. Suppl 2013年口頭発表（一般）
Evaluation of Rock Permeability Alteration by Long-term Flow-through Experiments and by Microstructural Investigation [通常講演]
H. Yasuhara, M. Takahashi, N. Kinoshita, S. Nakashima, K. Kishida
Proceedings of the 6th International Symposium on In-situ Rock Stress 2013年口頭発表（一般）
Evaluation of the enzymatic calcite precipitation technique to improve the physical and mechanical properties of sand [通常講演]
Debendra NEUPANE, Hideaki YASUHARA, Naoki KINOSHITA
13th Japan Symposium on Rock Mechanics & 6th Japan-Korea Joint Symposium on Rock Engineering 2013年口頭発表（一般）
動的解析による長支間ポケット式落石防護網の性能評価 [通常講演]
木下尚樹, 安原英明, 矢田部龍一
岩の力学国内シンポジウム講演論文集(CD-ROM) 2012年12月口頭発表（一般）
拘束圧・温度制御下における堆積岩の長期透水試験 [通常講演]
菊池紗帆, 安原英明, 木下尚樹, 高橋学
岩の力学国内シンポジウム講演論文集(CD-ROM) 2012年12月口頭発表（一般）
温度・鉱物溶解条件を制御した持続載荷試験による花崗岩不連続面の変形挙動評価 [通常講演]
崎山久美子, 木下尚樹, 安原英明, 川口隆
岩の力学国内シンポジウム講演論文集(CD-ROM) 2012年12月口頭発表（一般）
Slide‐hold‐slide型一面せん断試験における岩盤不連続面の形状変化と強度回復特性 [通常講演]
青山太郎, 矢野隆夫, 中島伸一郎, 安原英明, 岸田潔
岩の力学国内シンポジウム講演論文集(CD-ROM) 2012年12月口頭発表（一般）
Long-term evolution of rock permeability in sandstone and mudstone under pressure- and temperature-controlled conditions [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
46th US Rock Mechanics / Geomechanics Symposium 2012 2012年12月口頭発表（一般）
A suite of permeability experiments on intact rocks in sandstone and on a single fracture in siliceous mudstone has been conducted under confining pressures of 3-15 MPa, and at temperatures of 20-90°C for several hundred days in each experiment. For the mudstone experiments, oil-flow experiments are also conducted to examine the effect of mineral dissolution on the flow behavior - the oil-saturated condition refrains from the mineral dissolution and enables to certify if mechanical creep occurs under the stressed conditions. Evolution in permeability and dissolved mass fluxes were periodically measured to examine the flow behavior under stress and temperature conditions. In sandstone, the permeability of intact rocks little changed until a couple of hundred days, then started to increase with time. In mudstone, the permeability in a single fracture monotonically decreased with time and reached a quasi-steady state within one month. However, it started to increase with time after ∼100 days. This augmentation in the permeability in sandstone and mudstone should be attributed to mineral dissolution within void spaces. Copyright 2012 ARMA, American Rock Mechanics Association.
Evolution of fracture permeability in granite under temperature, confining pressure and pH conditions prescribed [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics 2012年02月
A suite of flow-through experiments in granite fracture is conducted under various temperature, confining pressure, and pH conditions, to examine the evolution of the fracture permeability. The well-controlled experiments are carried out at temperatures of 25 and 90°C, confining pressures of 5 and 10MPa, and pH's of 7 and 11. At 25°C, generally, the fracture permeability decreases with time and reaches a quasi-steady state within a few hundred hours. However, after the temperature is raised to 90°C, the permeability again resumed decreasing throughout the rest of the experimental periods. The higher temperature, confining pressure, and pH are prescribed, the faster evolutions of the fracture permeability are observed. These results may indicate that the near-field rock mass of HLW may become safer with time in terms of solute transport behavior. © 2012 Taylor & Francis Group, London.
Dependence of fracture geometry and spatial variation in pressure on hydraulic conductivity in rock fractures [通常講演]
K. Kishida, T. Hosoda, A. Sawada, H. Sato, S. Nakashima, H. Yasuhara
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics 2012年02月
Although it is generally known that a natural rock fracture indicates a complex aperture distribution, the fracture is an ideal representation of the parallel plate model. The cubic law is applied to evaluate the hydraulic properties of fractured rock. From several previous research works, it is known that the cubic law can be applied when the Reynolds number is less than 1.0 and that the advection term can basically be ignored in such fracture flows. In this research work, two-dimensional seepage flow analyses, using the authors' proposed 2D model which is considered with the advection term, are carried out for single fracture hydro-conductivity experiments under conditions which allow for the application of the cubic law. From the numerical results, the validity of the 2D model is discussed along with the local Reynolds number and the application of the cubic law. © 2012 Taylor & Francis Group, London.
Healing and Shear Stress Reduction on Single Fracture of Rock Salt and Limestone under Slide-Hold-Slide Direct Shear Condition [通常講演]
Kishida, K, Yano, T, Yasuhara, H
2012 Fall Meeting, AGU 2012年
Spontaneous Alteration of Rock Permeability under Constant Confining Pressure and Temperature Conditions [通常講演]
Hideaki Yasuhara, Manabu Takahashi, Naoki Kinoshita, Shinichiro Nakashima, Kiyoshi Kishida
Proc. 7th Asian Rock Mechanics Symposium (2012 ARMS7) 2012年
Healing and Shear Stress Reduction of Rock Salt Single Fracture under Slide-Hold-Slide Direct Shear Experiments [通常講演]
Kiyoshi Kishida, Takao Yano, Hideaki Yasuhara
Proc. 7th Asian Rock Mechanics Symposium (2012 ARMS7) 2012年
An Evaluation of the Effects of Fracture Diagenesis on Hydraulic Fracturing Treatment [通常講演]
Dae Sung. Lee, Derek Elsworth, Yasuhara Hideaki, Junhyung Choi, Wiri Heo
Proc. 7th Asian Rock Mechanics Symposium (2012 ARMS7)Proc. 7th Asian Rock Mechanics Symposium (2012 ARMS7) 2012年
Evaluation of cementation effect of sand mediated by enzyme-induced calcium carbonate precipitation [通常講演]
Hideaki Yasuhara, Debendra Neupane
The 2012 World Congress on Advances in Civil, Environmental, and Materials Research (ACEM’ 12) 2012年
Remedial measure for highway embankments on liquefaction prone foundation [通常講演]
M. Okamura, Y. Tomida, T. Okamoto, H. Yasuhara
Proc. Second International Conference on Performance –based Design Earthquake Geotechnical Engineering 2012年
凝灰岩における加温条件下での三軸応力保持中の力学的特性に関する研究 [通常講演]
荒木壯則, 矢野隆夫, 安原英明, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2012年
温度・pHを制御したフロースルー溶解試験による岩石溶解機構の検討 [通常講演]
橋本克樹, 安原英明, 木下尚樹
岩盤力学に関するシンポジウム講演集(CD-ROM) 2012年
Slide-hold-slide experiments on sedimentary rock under drained triaxial stress conditions [通常講演]
K. Kishida, T. Araki, T. Yano, H. Yasuhara, D. Elsworth
45th US Rock Mechanics / Geomechanics Symposium 2011年12月
When estimating the mechanical and the hydro-mechanical properties of rock masses over long periods of time, the influence of the effective confining stress and the thermal conditions should be incorporated. In this research work, slide-hold-slide triaxial experiments have been conducted on sedimentary soft rock under drained conditions. The experiments have been conducted under three patterns of effective confining stress conditions and several thermal conditions. Consequently, the strength recovery could be observed in the slide-hold-slide process under room temperature conditions. However, it could not be clearly observed under heated conditions. © 2011 ARMA, American Rock Mechanics Association.
Evolution in mechanical and hydraulic properties of calcite-cemented sand mediated by biocatalyst [通常講演]
H. Yasuhara, K. Hayashi, M. Okamura
Geotechnical Special Publication 2011年05月
A grouting technique that utilizes precipitated calcite as cohesive material is presented. An enzyme of urease is used to enhance the rate and magnitude of the calcite precipitation. Evolutions in the mechanical and hydraulic properties of sand samples treated are examined through the unconfined compression and permeability tests, respectively. The grout is composed mainly of urease that bio-catalyzes the hydrolysis of urea into carbon dioxide and ammonia, urea, and calcium chloride solution. This method employs chemical reactions catalyzed by the enzyme, and ultimately acquires calcite precipitated within soils. The experimental results show that even a small percentage of calcite precipitation against soils of interest improves the strength drastically compared with that of untreated soil. The evolution in hydraulic conductivity measured is replicated by a flow simulator accounting for the chemical reactions. The predictions show good agreement with the actual measurements. © 2011 ASCE.
Long-term evolution in intact and fracture permeability in sandstone and mudstone under stress and temperature conditions [通常講演]
H. Yasuhara, S. Nakashima, K. Kishida
Proc. 24th KKCNN Symposium on Civil Engineering 2011年
Theoretical discussion on healing process of single rock fracture through Shear-Hold-Shear direct shear experiments [通常講演]
K. Hashimoto, H. Yasuhara, T. Yano, K. Kishida
Proc. 24th KKCNN Symposium on Civil Engineering 2011年
Coupled chemical and mechanical effects on evolution of rock fracture permeability [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
Proc. The 2011 World Congress on Advances in Structural Engineering and Mechanics 2011年
Fracture permeability in granite under temperature, confining pressure, and pH conditions controlled: Measurements and predictions by coupled chemo-mechanical model [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
Proc. 4th Int. Conf. GeoProc 2011: Cross Boundaries Through THMC Integration 2011年
温度・拘束圧の負荷期間に依存するベレア砂岩の透水力学特性の評価 [通常講演]
鈴木崇史, 安原英明, 木下尚樹, 高橋学
岩盤力学に関するシンポジウム講演集(CD-ROM) 2011年
生体触媒反応を介したセメンテーションによる改良砂の力学特性 [通常講演]
鹿渡洸一, 林和幸, 木下尚樹, 安原英明
岩盤力学に関するシンポジウム講演集(CD-ROM) 2011年
堆積岩による排水三軸せん断‐保持‐せん断試験 [通常講演]
岸田潔, ELSWORTH Derek, 矢野隆夫, 安原英明, 中島伸一郎
岩盤力学に関するシンポジウム講演集(CD-ROM) 2011年
Stirred-flow-through experiments of granite under temperature and ph conditions controlled [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
44th US Rock Mechanics Symposium - 5th US/Canada Rock Mechanics Symposium 2010年12月
A series of stirred-flow-through experiments using granite powder has been conduced under temperature and pH conditions controlled so as to evaluate the dissolution kinetics of the Mizunami granite. The well-controlled experiments are carried out at temperatures of 30-70°C, and pH 6-13, and a constant flow rate of the permeant fluid is set to be 0.1 mL/min. The system likely reaches a quasi-steady state roughly 100 hrs after the experiments get started. Effluent concentrations are measured by regular sampling for the seven elements of Si, Al, K, Fe, Ca, Na, and Mg that are included mainly in the targeted rock. Relatively high concentrations of Si, K and Ca are observed throughout the experiment. Generically, the higher temperature and pH are prescribed, the faster dissolution rates are evaluated. Subsequently, dissolution rate constants of the granite itself are evaluated using a typical Arrhenius equation and an extended formation taking into account the dependence of pH. Copyright 2010 ARMA, American Rock Mechanics Association.
Measurement of fracture aperture in granite core using microfocus xray CT [通常講演]
S. Nakashima, D. Hasegawa, K. Kishida, H. Yasuhara
44th US Rock Mechanics Symposium - 5th US/Canada Rock Mechanics Symposium 2010年12月
Microfocus X-ray CT imaging was conducted on a granite core, 50 mm in diameter and 100 mm in length, containing a single fracture in the longitudinal direction. The three-dimensional geometry and the aperture distribution of the fracture were evaluated by analyzing the CT data. A very notable artifact called beam hardening was found in the obtained CT images because of the high X-ray absorption coefficient of the material compared with the source intensity of the X-rays. To reduce this phenomenon, two methods were applied when handling the CT data. One was to consider the slice direction when detecting the fracture route, and the other was to correct the CT data using a simulated image of the beam hardening of granite. Moreover, we developed a procedure to determine the fracture route automatically from the CT image. As a result, the spatially averaged aperture thickness and the contact ratio of the fracture asperities under unconfined conditions were estimated to be 0.39 mm and 2.0%, respectively. Copyright 2010 ARMA, American Rock Mechanics Association.
Experimental study on shear strength recovery of single rock fracture through slide-hold-slide direct shear test and its modeling [通常講演]
K. Kishida, Y. Kawaguchi, S. Nakashima, H. Yasuhara
44th US Rock Mechanics Symposium - 5th US/Canada Rock Mechanics Symposium 2010年12月
In this paper, slide-hold-slide type direct shear-flow coupling experiments on single rock fracture and its theoretical simulation are performed so as to investigate the effects of long-term load holding on the mechanical and hydro-mechanical properties of rock fractures. From the results, it is confirmed that the shear strength of the mortar replica specimens increases and the permeability decreases during three days of load holding. However, no significant changes are observed for the mechanical or the hydro-mechanical properties of the granite specimen even after twenty days of load holding. Moreover, to reproduce the shear strength recovery during short-time holding, we develop a direct shear model by employing a temporal variation in the dilation that occurs during load holding. The model predictions are in relatively good agreement with the experimental observations in the range of the short-holding period. Copyright 2010 ARMA, American Rock Mechanics Association.
In-situ test on desaturation by air injection and its monitoring [通常講演]
Mitsu Okamura, Masaya Takebayashi, Katsuji Nishida, Nao Fujii, Motoharu Jinguji, Takehiko Imasato, Hideaki Yasuhara, Emiko Nakagawa
Geotechnical Society of Singapore - International Symposium on Ground Improvement Technologies and Case Histories, ISGI'09 2010年11月
Desaturation of ground by air injection attracts considerable attention in resent years as an innovative technique for liquefaction countermeasure. Several research programs have been run in laboratories regarding related topics. This paper describes an in-situ air injection test which aimed to confirm the effectiveness of the air injection to desaturate ground and validity of observation techniques to monitor the evolution of unsaturated zone. Degree of saturation of the in-situ soil was observed using high quality undisturbed samples obtained by the ground freezing method. The degree of saturation ranged between 68% and 98%, which was low enough to almost double the liquefaction resistance of the soil at the site. 3D electric resistivity tomography technique was found to be effective to detect evaluation of the desaturated zone. Copyright © 2009 by Geotechnical Society of Singapore (GeoSS).
熱・水・応力・化学連成現象を考慮した岩盤不連続面の透水・物質輸送解析 [通常講演]
安原英明, 木下尚樹, 中島伸一郎, 岸田潔
日本鉱物科学会年会講演要旨集 2010年04月
Evaluation of Fracture Permeability in Granite Influenced by Stress and Temperature [通常講演]
D. Hasegawa, S. Nakashima, H. Yasuhara, K. Kishida
Proc. 23rd KKCNN Symposium on Civil Engineering 2010年
Physical Properties of Calcite-Cemented Sand Improved by Urease-Type Biogrout [通常講演]
H. Yasuhara, K. Hayashi, M. Okamura
Proc. 23rd KKCNN Symposium on Civil Engineering 2010年
Temporal alternation of fracture permeability in granite by mechanically- and chemically-mediated dissolution [通常講演]
H. Yasuhara
Proc. G-COE Symposium 2010 Dynamic Earth and Heterogeneous Structure 2010年
マイクロフォーカスX線CTによる花崗岩の亀裂形状および開口幅の評価 [通常講演]
中島伸一郎, 長谷川大貴, 安原英明, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2010年
温度・pHを制御した花崗岩のフロースルー溶解試験 [通常講演]
川下慧, 喜多亮太, 安原英明, 木下尚樹
岩盤力学に関するシンポジウム講演集(CD-ROM) 2010年
応力・温度が与える花崗岩不連続面の透水性への影響 [通常講演]
長谷川大貴, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚
岩盤力学に関するシンポジウム講演集(CD-ROM) 2010年
Evolution of shear strength and permeability during shear-holding in a simulated rock fracture under moderate stress and room temperature condition [通常講演]
Y. Kawaguchi, S. Nakashima, K. Kishida, H. Yasuhara, Y. Takao, T. Hosoda
43rd U.S. Rock Mechanics Symposium and 4th U.S.-Canada Rock Mechanics Symposium 2009年11月
This paper presents direct shear test results for single jointed granite and mortar specimens to investigate effects of long-term load holding on mechanical and hydrological properties of rock joints. From the test results, it was confirmed that shear strength increased and permeability decreased for mortar specimens through three days load holding. For granite specimens, however, significant change was not observed on mechanical and hydrological properties even after the twenty-day load holding, which is likely due to low confining pressure relative to the strength of granite and insufficient load holding period. Copyright 2009 ARMA, American Rock Mechanics Association.
Evolution of fracture permeability in granite and its evaluation via coupled chemo-mechano conceptual model [通常講演]
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida
43rd U.S. Rock Mechanics Symposium and 4th U.S.-Canada Rock Mechanics Symposium 2009年11月
A coupled chemo-mechano conceptual model is presented to follow the evolution of fracture permeability observed in flow-through experiments in a single rock fracture in granite. The experiments are conducted under constant confining pressures of 5 and 10 MPa with differential water pressures ranging 0.01-0.5 MPa, and temperatures of 20 and 90°C. Permeability measured shows a monotonic decrease with time, via apparent steady state after relatively short periods at 20°C. A presented model addresses the two dissolution processes at contacting asperities and free walls within fractures, and also describes the multimineral dissolution behavior, showing a capability that the evolution of fracture aperture (or related permeability) may be followed with time under an arbitrary temperature and pressure conditions. Predictions utilizing the model proposed in this study show a relatively good agreement with the experimental measurements, although an abrupt reduction observed is incapable of being replicated, that is due to an unaccounted effect in the current model. Copyright 2009 ARMA, American Rock Mechanics Association.
An evaluation of the effects of fracture diagenesis on fracture treatments: Modeled response [通常講演]
D. S. Lee, D. Elsworth, H. Yasuhara, J. Weaver, R. Rickman
43rd U.S. Rock Mechanics Symposium and 4th U.S.-Canada Rock Mechanics Symposium 2009年11月
Observed reductions in the permeability of propped hydraulic fractures are examined by considering the role of mechanical stresses and the chemistry of pore fluids at elevated temperatures as agents of proppant diagenesis. Stress-enhanced dissolution of proppant increases the density of grain packing and reprecipitation of mineral matter further occludes pores - together these mechanisms additively reduce porosity and permeability. Experiments and analyses are presented which explore the evolution of porosity and permeability in proppant packs subjected to reservoir conditions. Experiments are completed in two modes: in flow-through reactors absent intergranular stresses to evaluate rates of dissolution and reprecipitation on proppant surfaces; and in uniaxially stressed reactors with stagnant fluids to evaluate the relative role of stress in mediating dissolution and porosity reduction. Lumped parameter models are used to evaluate rates of dissolution and chemical compaction in a range of proppants. Mechanisms include mineral dissolution, transport, and re-precipitation of the resulting products in the particle interstices, resulting in a loss of intergranular porosity. The model uses thermodynamic data recovered from the reactor experiments to constrain the projected loss of permeability for the mineralogical composition of available proppants. Copyright 2009 ARMA, American Rock Mechanics Association.
Predicting temporal change of fracture permeability in granite via chemical-mechanical coupling model [通常講演]
H. Yasuhara, S. Nakashima, K. Kishida
Proc. 22nd KKCNN Symposium on Civil Engineering 2009年
Estimation on shear strength and permeability during shear-holding single rock fracture [通常講演]
K. Kishida, Y. Kawaguchi, S. Nakashima, H. Yasuhara
Proc. 22nd KKCNN Symposium on Civil Engineering 2009年
岩盤不連続面におけるせん断挙動とその時間依存性の評価 [通常講演]
川口雄大, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚
資源・素材 2009年
三軸せん断過程における堆積軟岩の構造変化と透水性に関する実験的検討 [通常講演]
河合祐輔, 中島伸一郎, 安原英明, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2009年
花崗岩不連続面の透水実験―拘束圧・温度条件に起因する鉱物溶解の影響 [通常講演]
重永三郎, 西山曜平, 木下尚樹, 安原英明
岩盤力学に関するシンポジウム講演集(CD-ROM) 2009年
岩盤不連続面のせん断透水試験と三乗則の適用性について [通常講演]
岸田潔, 中島伸一郎, 安原英明, 細田尚
岩盤力学に関するシンポジウム講演集(CD-ROM) 2009年
A study of thermal behavior of the openings effected by high temperatures [通常講演]
N. Kinoshita, H. Yasuhara, Y. Inada
12th International Conference on Computer Methods and Advances in Geomechanics 2008 2008年12月
The authors have proposed and discussed temporary storage of heated water in openings excavated in rock mountain from the viewpoints of multiple-utilization of land, environmental safeguards, energy conservation, etc. When used for heated-water storage, the rock mass around the openings will receive the effects of the heated water. In this study, a uniaxial compression creep test at high temperatures of the rock was also carried out, then the calculation of various constants on the creep was tried. Using the results obtained in this work, temperature and stress distribution around the openings when heated water were stored was analyzed by considering the creep properties. The thermal behavior and stability of the openings were also examined. The displacement of the openings was predicted to be 1.96 % of the diameter after one thousand days.
Estimation of ground stability in considering groundwater and air bubbles using multiphase simulator [通常講演]
K. Kishida, N. Jacimovic, N. Jacimovic, T. Hosoda, S. Nakashima, T. Kodaka, H. Yasuhara
42nd U.S. Rock Mechanics - 2nd U.S.-Canada Rock Mechanics Symposium 2008年12月
In this paper, the two-phase (water and air) numerical model which considers the thermal and the dissolved oxygen process has been developed. In order to verify the performance of developed numerical simulator and discuss the progressive failure of the seepage flow, the simple two-dimensional seepage flow experiments along/below a vertical sheet pile have been simulated. In consequent, the simulation results shows the same tendency as the experimental results and the instability due to generated air bubbles can be expressed in our developed Copyright 2008, ARMA, American Rock Mechanics Association.
Experimental study on the permeability of soft rock during the triaxial shear process [通常講演]
Yusuke Kawai, Shinichiro Nakashima, Kiyoshi Kishida, Hideaki Yasuhara
42nd U.S. Rock Mechanics - 2nd U.S.-Canada Rock Mechanics Symposium 2008年12月
Soft sedimentary rocks have a characteristic behavior, dilatancy. Changes of stress conditions may cause shearing with volume expansion/compression. When a rock sample is compressed, its volume is subsequently changed, resulting that the flow-paths might be also evolved. Thus, permeability within a domain is influenced by volumetric strain mediated by alternation of stress conditions. This alternation of permeability may exert influence over stress conditions because the water pressure may change under an undrained condition. Therefore, this linked alternation processes among stress conditions, volumetric strain, and permeability, should be considered. This paper is aimed to examine the coupled mechanical and hydraulic behavior by conducting triaxial compressive and flow-through experiments using pumice tuff, and then a relation between volumetric strain and permeability is proposed. After the experiments are terminated, X-ray CT analysis is conducted to examine in-sample microscopic structures, focusing on fractures induced by the compression and flow tests. © 2008, ARMA, American Rock Mechanics Association.
拘束圧および温度を制御した花崗岩不連続面の透水性経時変化の実験による検討 [通常講演]
木下尚樹, 安原英明, 中島伸一郎, 岸田潔
岩の力学国内シンポジウム講演論文集 2008年09月
力学‐化学連成モデルによる花崗岩不連続面の透水挙動評価 [通常講演]
安原英明, 木下尚樹, 中島伸一郎, 岸田潔
岩の力学国内シンポジウム講演論文集 2008年09月
不連続面の一面せん断試験における負荷状態保持の効果 [通常講演]
川口雄大, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚
岩の力学国内シンポジウム講演論文集 2008年09月
Temporal alternation of rock permeability by mechanically- and chemically-mediated dissolution: Aiming at an application to safe and long-term isolation of high level radioactive wastes [通常講演]
Yasuhara, H
Proc. Int. Conf. Disasters and Developments 2008年
Evolution of soil desaturation by air-injection technique and its evaluation via multiphase flow simulator [通常講演]
Yasuhara, H, T. Morito, Y. Kochi, M. Okamura
Proc. 6th Int. Conf. Case Hist. Geotech. Eng., Arlington, Virginia 2008年
Evolution of permeability in siliceous rocks by dissolution and precipitation under hydrothermal conditions [通常講演]
Yasuhara, H, N. Kinoshita, H. Kurikami, S. Nakashima, K. Kishida
GeoProc 2008. Proc. 3rd Int. Conf. on Coupled T-H-M-C Processes in Geosystems and Applications 2008年
熱水環境下における岩盤空洞の熱挙動に関する一考察 [通常講演]
木下尚樹, 安原英明
岩盤力学に関するシンポジウム講演集(CD-ROM) 2008年
堆積軟岩のダイレイタンシー特性が透水性に及ぼす影響について [通常講演]
河合祐輔, 中島伸一郎, 安原英明, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2008年
サブクリティカル亀裂進展および圧力溶解を考慮した岩盤不連続面の圧縮挙動評価 [通常講演]
安原英明, 木下尚樹, 中島伸一郎, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2008年
熱水環境下における各種岩石の透水特性の経時変化 [通常講演]
安原英明, 木下尚樹
土木学会年次学術講演会講演概要集(CD-ROM) 2007年09月
熱水貯蔵システムにおける岩盤空洞の挙動について [通常講演]
木下尚樹, 安原英明, 友永翔太
土木学会年次学術講演会講演概要集(CD-ROM) 2007年09月
気液二相流解析による空気注入時の地盤飽和度変化予測 [通常講演]
森藤隆元, 安原英明, 岡村未対, 河内義範
地盤工学研究発表会発表講演集 2007年06月
圧力溶解現象を考慮した珪藻質岩石の透水性評価 [通常講演]
安原英明, 操上広志, 木下尚樹, 岸田潔
岩盤力学に関するシンポジウム講演集(CD-ROM) 2007年
Numerical simulation of coupled thermo-hydro-chemo-mechanical processes through the linking of hydrothermal and solid mechanics codes [通常講演]
J. Taron, K. B. Min, H. Yasuhara, K. Trakoolngam, D. Elsworth
Proceedings of the 41st U.S. Rock Mechanics Symposium - ARMA's Golden Rocks 2006 - 50 Years of Rock Mechanics 2006年12月
A numerical simulator is developed to examine coupled thermal-hydrologic- mechanical-chemical (THMC) processes in fractured porous geological media. The simulator links the computational codes TOUGHREACT and FLAC3D, which individually model thermal-hydrologic-chemicalTHC) and mechanical (M) processes, respectively. The coupled scheme is shown capable of representing undrained response of saturated media to mechanical loading. Embryonic mechanical and transport constitutive laws are developed which are capable of accommodating combined mechanical, thermal, and chemical effects. Initial characterizations note the significant anticipated influence of stress on chemical behavior. The coupled model is applied to examine the evolution of pore fluid pressures, stresses, and temperatures in a stimulated EGS geothermal reservoir where the effects of stresses on multiphase reactive flow are important Copy; 2006, ARMA, American Rock Mechanics Association.
Long-term evolution of the transport proprieties of a fracture from the Coso Geothermal reservoir [通常講演]
I. Faoro, H. Yasuhara, A. Grader, P. Halleck, D. Elsworth, C. Marone
Proceedings of the 41st U.S. Rock Mechanics Symposium - ARMA's Golden Rocks 2006 - 50 Years of Rock Mechanics 2006年12月
Results are reported for a long-term circulation test on a calcite-filled fracture in diorite from the Coso Geothermal Field, California. Deionised water is circulated thought the fracture at 20°, then 60°, and then 90°C under a near constant effective stress of 13 MPa. Through the initial stages of the test, at 20°C, the fracture aperture drops from an initial mean hydraulic aperture of 30 μm to 0.6 μm in the first 100 hours, before reaching a steady magnitude. This corresponds to a net reduction in permeability of 7∼ 4 orders of magnitude through the initial duration of the experiment, and under constant stress. As temperature is increased, the average aperture further reduces, and a periodic change in hydraulic impedance is recorded under conditions of constant stress, temperature and pressure-controlled flow rate. The peak cyclic flow rate climbs rapidly to about 20 times the steady magnitude, within a period of 6000 minutes, and is interpreted as periodic clogging and flushing of mineral mass from the constricted and brecciated end of the sample. As the temperature is increased to 90°C the hydraulic impedance continues to decrease, ultimately reaching a final aperture of 1 μm and flow rate of 0.03 cc/min. This low magnitude of ultimate permeability persists, despite visible open voids within the calcite vein, implicating that much of this porosity is not well connected. Since effective stresses remain constant, this observed response is strongly conditioned by the evolving aqueous chemistry of the sample. Analysis of the data continues. © 2006, ARMA, American Rock Mechanics Association.
化学溶解現象を考慮した不連続面透水性解析 [通常講演]
安原英明, ELSWORTH Derek
地盤工学研究発表会発表講演集 2006年06月
A numerical model simulating evolution of fracture permeability moderated by mechanically- and chemically-induced dissolution [通常講演]
Yasuhara, H, D. Elsworth
GeoProc 2006. Proc. 2nd Int. Conf. on Coupled T-H-M-C Processes in Geosystems and Engineering 2006年
Modeling of the kinetics of silica polymerization and precipitation in aqueous solutions as a function of pH and ionic strength [通常講演]
Conrad, C. F, P. J. Heaney, J. Brandstra, G. Icopini, H. Yasuhara, S. L. Brantley
Eos Trans. AGU, 86(52), Fall Meet. Suppl. 2005年
Constrained observations of stress- and chemistry mediated changes in the transport properties of fractured rocks via physical and chemical signals supplemented by X-ray CT [通常講演]
Elsworth, D, H. Yasuhara, J. Liu, A. Polak, A. Grader, P. Halleck
Eos Trans. AGU, 86(52), Fall Meet. Suppl. 2005年
Short-timescale chemo-mechanical effects and their influence on the transport properties of fractured rock [通常講演]
Elsworth, D, H. Yasuhara, A. Polak, J. Liu
11th Int. Conf. on Computational Methods and Advances in Geomechanics 2005年
The evolution of permeability in natural fractures - the competing roles of pressure solution and free-face dissolution [通常講演]
A. Polak, H. Yasuhara, D. Elsworth, J. Liu, A. Grader, P. Halleck
Elsevier Geo-Engineering Book Series 2004年12月
Fracture permeabilities are shown surprisingly sensitive to mineral dissolution at modest temperatures (c. 20°-80°C) and flow rates. Net dissolution may either increase or decrease permeability, depending on the prevailing ambient THMC conditions. These behaviours have important ramifications for constitutive laws for flow and transport. Flow-through tests are completed on a natural fracture in novaculite at temperatures of 20°C, 80°C, 120°C, and 150°C, and on an artificial fracture in limestone at 20°C. Measurements of fluid and dissolved mass fluxes, concurrent X-ray CT and imaging, and post-test sectioning and SEM are used to constrain the progress of mineral dissolution and its effect on transport properties. For the novaculite, under constant effective stress, fracture permeability decreased monotonically with an increase in temperature, with fracture permeability reducing by two-orders-of-magnitude over the 900 h test. For the limestone, an initial decrease in permeability over the first 935h of the test, switched to a net increase in permeability as distilled water was subsequently circulated for the final 500h of the test. © 2004 Elsevier Ltd. All rights reserved.
Compaction and diagenesis of sandstones - the role of pressure solution [通常講演]
Hideaki Yasuhara, Derek Elsworth, Amir Polak
Elsevier Geo-Engineering Book Series 2004年12月
A model is presented for the compaction of granular aggregates that accommodates the serial processes of grain-contact dissolution, grain-boundary diffusion, and precipitation at the pore wall. Impor-tantly, this treatment follows the progress of grain interpenetration as contact areas grow, mass transport lengths increase, and rate-limiting processes may switch with the progress of compaction. A simple repeating closed system incorporates two stressed grains in contact and enables the progress of compaction, and the evolution of the mass concentration of the pore fluids to be followed with time, for arbitrary mean stress, fluid pressure, and temperature conditions. Hindcast comparisons with experimental results for the compac-tion of quartz sand in a closed system (Elias and Hajash, 1992) show excellent agreement for rates of change of porosity, the asymptotic long-term porosity, and for the development of silica concentrations in the pore fluid with time. © 2004 Elsevier Ltd. All rights reserved.
Enigmatic permeability switching in fractures under net dissolution [通常講演]
Yasuhara, H, A. Polak, D. Elsworth, A. Grader, P. Halleck
Eos Trans. AGU, 85(47), Fall Meet. Suppl. 2004年
Coupled chemical-mechanical effects and their influences on the transport properties of fractures in rock [通常講演]
Elsworth, D, A. Polak, H. Yasuhara, A. Grader
11th Geosciences Research Program Symposium – Flow and Transport: Characterization and Modeling from Pore to Reservoir Scales 2004年
Evolution of strength recovery in simulated fault gouge – the role of pressure solution [通常講演]
Yasuhara, H, D. Elsworth, C. Marone
Euro-Conference 2004 on Rock Physics and Geoomechanics 2004年
Quantitative constrained imaging of dissolution and precipitation in a natural fracture [通常講演]
Elsworth, D, A. Polak, A. S. Grader, H. Yasuhara, P. M. Halleck, S. L. Brantley
Eos Trans. AGU, 83(47), Fall Meet. Suppl. 2002年
ラフネス計測結果を用いた不連続面せん断挙動の推定 [通常講演]
安原英明, 岸田潔, 足立紀尚
岩盤力学に関するシンポジウム講演論文集 2001年01月
X-ray imaging of changes in permeability due to dissolution and precipitation in fractured Berea sandstone [通常講演]
Elsworth, D, A. Polak, H. Yasuhara, A. S. Grader, S. L. Brantley, P. M. Halleck
Multiscale Reservoir Investigations and Applications to Terrestrial CO2 Sequestration Symposium 2001年
応力比一定載荷試験における岩盤不連続面のダイレイタンシー特性の考察 [通常講演]
岸田潔, 安原英明, 足立紀尚
岩盤力学に関するシンポジウム講演論文集 2000年01月
Experimental study on the dilatancy behavior of single joint under constant τ/σ loading conditions [通常講演]
K. Kishida, H. Yasuhara, T. Adachi
Proc. Fourth North Ame. Rock Mech. Symp. 2000年
応力比一定試験による岩盤不連続面剛性の決定に関する一孝察 [通常講演]
藤井浩司, 足立紀尚, 岸田潔, 安原英明
地盤工学研究発表会発表講演集 1999年06月
応力比一定下での不連続面の変形特性 [通常講演]
安原英明, 岸田潔, 藤井浩司, 足立紀尚
岩盤力学に関するシンポジウム講演論文集 1999年01月
Experimental study on the mechanical behavior of single joint under a constant τ/σ loading condition and its application to mechanical modeling [通常講演]
Yasuhara, H, Kishida, K, H. Fujii, T. Adachi
Proc. 37th U.S. Rock Mech. Symp. 1999年
岩盤不連続面剛性を考慮した連続体解析に関する一考察 [通常講演]
安原英明, 足立紀尚, 岸田潔
土木学会関西支部年次学術講演会講演概要 1998年05月

MISC
MISC
Simulations of flow-through experiments using the granite fractures by THMC coupled model considering pH dependence
Takeru Kumagai, Hideaki Yasuhara, Naoki Kinoshita, Sho Ogata Proceedings of the YSRM2019 & REIF2019 記事・総説・解説・論説等（国際会議プロシーディングズ） P-29 2019年12月 [査読有り]
Numerical Investigation for Modeling Lahendong Geothermal Field, North Sulawesi, Indonesia
Muhammad Qarinur, Hideaki Yasuhara, Naoki Kinoshita, Sho Ogata Proceedings of the YSRM2019 & REIF2019 記事・総説・解説・論説等（国際会議プロシーディングズ） 2-1-3 2019年12月 [査読有り]
pH依存を考慮した連成解析モデルによる花崗岩の透水実験再現解析
熊谷丈瑠, 安原英明, 木下尚樹, 緒方奨地盤四国支部令和元年度技術研究発表会講演概要集研究発表ペーパー・要旨（全国大会，その他学術会議） 49 -50 2019年11月
Effect of contact-area variation within a single granite fracture on hydraulic properties
Song, C.L, Nakashima, S, Yasuhara, H, Kishida, K Proc. of the 32nd KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） (KU-38) 2019年10月
損傷理論を実装した連成数値シミュレータによる岩盤の長期透水特性評価
緒方奨, 安原英明, 岸田潔第74回土木学会年次学術講演会講演集研究発表ペーパー・要旨（全国大会，その他学術会議） III-317 2019年09月
Experimental Study on Long-term Permeability Change at different temperatures
Chenlu SONG, Hideaki YASUHARA, Shinichiro NAKASHIMA, Kiyoshi KISHIDA 第54回地盤工学研究発表会講演集研究発表ペーパー・要旨（全国大会，その他学術会議） 17 -18 2019年07月
亀裂発生・進展を考慮した熱・水・応力・化学連成解析モデルの開発
緒方奨, 安原英明, 岸田潔第54回地盤工学研究発表会講演集研究発表ペーパー・要旨（全国大会，その他学術会議） 417 -418 2019年07月
鉱物分布を考慮した岩石のき裂進展シミュレータ法の提案
伊澤正悟, 緒方奨, 安原英明, 木下尚樹, 岸田潔 2019年度土木学会関西支部年次学術講演会研究発表ペーパー・要旨（全国大会，その他学術会議） III-12 2019年05月
亀裂発生・進展を考慮したマルチフィジックスシミュレータの開発
緒方奨, 安原英明, 岸田潔第46回岩盤力学に関するシンポジウム講演集（CD-ROM）研究発表ペーパー・要旨（全国大会，その他学術会議） No.83 282 -286 2019年01月 [査読有り]
Evaluation on the healing of single rock fracture with consideration of the critical state during slide-hold-slide process
Matsumoto, K, Yasuhara, H, Yano, T, Kishida, K Proc. of the 31st KKHTCNN Symposium on Civil Engineering KU-22 2018年11月
Permeability variation of granite single fracture in considering influence of temperature and stress confining period
Song., C, Nakashima, S, Yasuhara, H, Kishida, K Proc. of the 31st KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） KU-21 2018年11月
Multi-physics modeling by incorporating damage theory for evaluating rock permeability change
Ogata, S, Yasuhara, H, Kishida, K Proc. of the 31st KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） KU-23 2018年11月
切羽に出現しない弱層部がトンネル掘削に与える影響に関する基礎的研究
賀島諒太, 緒方奨, 安原英明, 岸田潔第73回土木学会年次学術講演会研究発表ペーパー・要旨（全国大会，その他学術会議） 2018年08月
熱・水・応力・化学連成解析モデルによる単一不連続面浸透流解析
緒方奨, 安原英明, 岸田潔第73回土木学会年次学術講演会研究発表ペーパー・要旨（全国大会，その他学術会議） 2018年08月
Sustainability of Enzyme-Mediated Calcite Precipitation Method as an Environmental-Friendly Soil Improvement Technique
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita Proc. The 2018 World Congress on Advances in Civil and Environmental, Materials Research (ACEM18) 研究発表ペーパー・要旨（国際会議） W4B.2.GE2181_4604F1 2018年08月
岩石不連続面における圧力溶解を考慮した熱・水・応力・化学連成解析モデルの開発とその性能評価
緒方奨, 安原英明, 岸田潔第53回地盤工学研究発表会研究発表ペーパー・要旨（全国大会，その他学術会議） 2018年07月
Experimental Study on Long-term Change in Permeability of Rock Fracture under Constant Normal Stress
Chenlu Song, Takao Yano, Hideaki Yasuhara, Shinichiro Nakashima, Kiyoshi Kishida 第53回地盤工学研究発表会研究発表ペーパー・要旨（全国大会，その他学術会議） 2018年07月
岩石不連続面のSHS型一面せん断試験と速度・状態を考慮した応力回復現象の評価
松本航佑, 矢野隆夫, 安原英明, 岸田潔第45回岩盤力学に関するシンポジウム講演集研究発表ペーパー・要旨（全国大会，その他学術会議） 202 -207 2018年01月 [査読有り]
Dual porosity理論を考慮した連成シミュレータによる岩盤浸透流解析
緒方奨, 安原英明, 岸田潔第 45 回岩盤力学に関するシンポジウム講演集研究発表ペーパー・要旨（全国大会，その他学術会議） 281 -286 2018年01月 [査読有り]
花崗岩不連続面における透水実験と鉱物溶解機構の検討
廣惠なつ美, 安原英明, 木下尚樹岩盤力学に関するシンポジウム講演集(CD-ROM) 45th ROMBUNNO.47 2018年01月
NGH貯蔵を想定した地下空洞の変形挙動評価
SON Wonjun, 安原英明, 木下尚樹岩盤力学に関するシンポジウム講演集(CD-ROM) 45th ROMBUNNO.20 2018年01月
Coupled THMC modeling by considering damage theory for predicting permeability change in fractured rocks
S. Ogata, H. Yasuhara, N. Kinoshita, K. Kishida 2nd International Discrete Fracture Network Engineering Conference, DFNE 2018 2018年01月
Copyright 2018 ARMA. We developed a coupled thermal-hydraulic-mechanical-chemical (THMC) simulator, iPSACC (interface for Pressure Solution Analysis under Coupled Conditions) that can consider the coupled processes including change of physical properties of the rocks due to the cracking by incorporating elastic damage theory. Especially, modeling the relationships between geochemical reactions such as pressure solution within rock fracture and rock damage is most important characteristic of this simulator. By using the developed simulator, long-term prediction of rock permeability was conducted by assuming subsurface environment near the radioactive waste repository. The predictions show that in EDZ many fractures occur near the disposal cavity and permeability increases in damaged zone during the excavation, and after excavation the permeability of the damaged zone decreases with time due to pressure solution at contacting asperities within fractures. It is concluded that pressure solution within the fractures has significant impact on the change of the permeability in EDZ area by cavity excavation.
Coupled thermal-hydraulic-mechanical-chemical modeling for predicting the evolution of permeability on fractured rocks
Ogata, S, Yasuhara, H, Kishida, K Proc. of the 30th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） (KU43) 2017年11月
Dual porosity理論を用いた熱・水・応力・化学連成解析モデルの開発と不連続性岩盤への適用
緒方奨, 安原英明, 岸田潔第38回西日本岩盤シンポジウム研究発表ペーパー・要旨（全国大会，その他学術会議） 2017年09月
熱・水・応力・化学連成解析モデルによる不連続性岩盤の長期透水特性予測解析
緒方奨, 岸田潔, 安原英明第72回土木学会年次学術講演会研究発表ペーパー・要旨（全国大会，その他学術会議） 807 -808 2017年09月
Innovative and Eco-friendly Soil Treatment Technologies Preface
Hideaki Yasuhara, Ilhan Chang GEOMECHANICS AND ENGINEERING その他 12 (5) I -I 2017年05月
持続載荷せん断試験による岩石不連続面の変形特性評価
岡本哲徳, 安原英明, 木下尚樹岩の力学国内シンポジウム講演論文集(CD-ROM) 14th ROMBUNNO.104 2017年01月
Numerical modeling of coupled THMC processes for predicting fluid flow and transport behavior within fractured rocks
S. Ogata, H. Yasuhara, N. Kinoshita, K. Kishida 51st US Rock Mechanics / Geomechanics Symposium 2017 研究発表ペーパー・要旨（国際会議） 2 1156 -1159 2017年01月
© 2017 ARMA, American Rock Mechanics Association. We improved our thermal-hydraulic-mechanical-chemical (THMC) simulator to predict the long-term permeability change of the fractured rocks. The model evaluates the influence of the geochemical reaction on the evolution of the permeability in fractured rocks by considering pressure solution in detail. Pressure solution that occurs at both grain contacts and contacting asperities within fractures was incorporated in the model. By using the developed THMC numerical model, long-term prediction of rock permeability was conducted by replicating the subsurface environment near the radioactive waste repository. As a result of the analyses, the permeability decrease by two orders of magnitude smaller than the initial value occurs due to pressure solution at contacting asperities within fractures in the EDZ area. In carrying out radioactive waste disposal, it is apparent that pressure solution within the fractures has significant impact on minimizing the increase of the permeability in EDZ area.
圧力溶解と岩盤・地層処分:連成数値シミュレータを用いた天然バリアの長期透水特性評価
緒方奨, 安原英明, 木下尚樹岩の力学国内シンポジウム講演論文集(CD-ROM) 14th ROMBUNNO.83 2017年
熱環境における堆積岩不連続面の変形・透水特性について
木下尚樹, 安原英明資源・素材(Web) 研究発表ペーパー・要旨（全国大会，その他学術会議） 2017 ROMBUNNO.3301‐04‐03 (WEB ONLY) 2017年
Estimation on SHS Process Strength Recovery through Rock Specimen Included Artificial Cutting Plane
Sakai, S, Yano. T, Yasuhara, H, Ohno, M, Kishida, K Proc. of the 29th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） 263 -266 2016年12月
圧力溶解を考慮した熱・水・応力・化学連成解析モデルの高度化と流体解析
緒方奨, 安原英明, 木下尚樹地盤工学会四国支部平成28年度技術研究発表会講演概要集研究発表ペーパー・要旨（全国大会，その他学術会議） 25 -26 2016年11月
Evolution of Rock Permeability Evaluated by Coupled Thermal-Hydraulic-Mechanical-Chemical Model
H. Yasuhara, N. Kinoshita, K. Kishida Proc. 9th Asian Rock Mechanics Symposium 研究発表ペーパー・要旨（国際会議） 2016年10月
拘束圧作用下での花崗岩不連続面の透水性の変化
岸田潔, 石川智優, 矢野隆夫, 安原英明第51 回地盤工学研究発表会研究発表ペーパー・要旨（全国大会，その他学術会議） 935 -936 2016年09月
熱環境における岩石不連続面の透水・変形挙動について
木下尚樹, 安原英明, 岡本哲徳資源・素材(Web) 研究発表ペーパー・要旨（全国大会，その他学術会議） 2016 (2) ROMBUNNO.3504 (WEB ONLY) 2016年09月
Enzyme-mediated carbonate precipitation (EMCP) for soil improvement: the effect of magnesium substitution
Hideaki Yasuhara, Heriansyah Putra, Naoki Kinoshita Proc. The 2016 World Congress on Advances in Civil and Environmental, Materials Research (ASEM16) 研究発表ペーパー・要旨（国際会議） 2016年08月
岩盤の透水挙動評価を目的とした連成数値シミュレーション
緒方奨, 安原英明, 木下尚樹日本材料学会第65期学術講演会論文集研究発表ペーパー・要旨（全国大会，その他学術会議） No.109 17 -18 2016年05月
Permeability Experiment in a Single Granite Fracture under Different Stress, Temperature, and pH Conditions
Hideaki Yasuhara, Naoki Kinoshita, Dae-Sung Cheon, Kiyoshi Kishida Proc. 2016 Korea-Japan Symposium on Rock Mechanics Engineering 研究発表ペーパー・要旨（国際会議） 2016年05月
プロパント処理した岩盤亀裂の透水特性評価
菅野巧, 安原英明, 木下尚樹, LEE Dae‐Sung 岩盤力学に関するシンポジウム講演集(CD-ROM) 44th ROMBUNNO.46 2016年01月
気液二相流解析による岩盤空洞周辺のガス移行挙動評価
石中亮, 安原英明, 木下尚樹, 下茂道人岩盤力学に関するシンポジウム講演集(CD-ROM) 44th ROMBUNNO.66 2016年01月
Predictions of rock permeability by THMC model considering pressure solution
H. Yasuhara, N. Kinoshita, K. Kishida 50th US Rock Mechanics / Geomechanics Symposium 2016 研究発表ペーパー・要旨（国際会議） 2 1242 -1245 2016年01月
Copyright 2016 ARMA American Rock Mechanics Association. A coupled thermos-hydro-mechanical-chemical (THMC) numerical model is presented to predict the long-term change in permeability of the porous rocks that are composed purely of quartz. Especially, the chemo-mechanical process of the pressure dissolution is explicitly taken into account in the model. By simulating the burial of high-level radioactive wastes in the deep subsurface (i.e., by applying the simulated confining pressure and temperature conditions), the long-term evolution of the rock permeability was predicted using the model. The predictions obtained a significant influence of the pressure dissolution on the change in permeability with time. The predicted permeability of the rocks close to the wastes decreased by roughly one order of magnitude in 104 years when considering the pressure dissolution, while the permeability changed little during the same period when the pressure dissolution was not considered. The reduction should delay the transportation of the radioactive materials.
熱・水・応力・化学連成解析モデルによる岩盤の長期透水特性評価
緒方奨, 安原英明, 木下尚樹岩盤力学に関するシンポジウム講演集(CD-ROM) 44th ROMBUNNO.62 2016年01月
熱・水・応力・化学連成解析モデルによる岩盤の長期透水特性予測
緒方奨, 安原英明, 木下尚樹地盤工学会四国支部平成27年度技術研究発表会講演概要集研究発表ペーパー・要旨（全国大会，その他学術会議） 45 -46 2015年11月
Coupled THMC model to predict long-term evolution of rock permeability
Yasuhara, H, Kishida, K Proc. of the 28th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） KU-GTE-06, 2015年11月
Permeability of a single fracture in granite under the confining pressure and extraction of fracture structure using microfocus X-ray CT
Ishikawa, T, Yasuhara, H, Higo, Y, Kishida, K Proc. of the 28th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） KU-GTE-03 2015年11月
強アルカリ環境における花崗岩不連続面の透水試験
前田健太, 安原英明, 木下尚樹資源・素材講演集 2 (2) 3410 2015年09月
Evaluation of long-term permeability change of natural barrier by THMC numerical simulation model
Sho Ogata, Hideaki Yasuhara, Naoki Kinoshita Proceedings of the 2015 East Asian Symposium on Civil & Environmental Technology 記事・総説・解説・論説等（国際会議プロシーディングズ） 135 -138 2015年08月 [査読有り]
Optimization of calcite precipitation as a soil improvement technique
Heriansyah Putra, Hideaki Yasuhara, Naoki Kinoshita, Debendra Neupane Proc. the 2nd Makassar International Conference on Civil Engineering (MICCE 2015) 研究発表ペーパー・要旨（国際会議） 2015年08月
熱・水・応力・化学連成解析モデルによる天然バリアの長期透水特性予測
緒方奨, 安原英明, 木下尚樹平成27年度土木学会四国支部第21回技術研究発表会公園概要集（CD-ROM）研究発表ペーパー・要旨（全国大会，その他学術会議） Ⅲ-11 137 -138 2015年05月
CHEMICALLY- AND MECHANICALLY-DRIVEN ALTERATION OF PERMEABILITY IN FRACTURED ROCKS UNDER DIFFERENT STRESS, TEMPERATURE, AND PH CONDITIONS
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida Proc. the 13th International Congress of Rock Mechanics, ISRM Congress 2015 研究発表ペーパー・要旨（国際会議） 508 2015年03月
Structural healing and decay of sedimentary soft rock under slide-hold-slide process and their constitutive description
Vu, N.P.Q, Kikumoto, M, Ohono, M, Yasuhara, H, Kishida, K Proceedings of the 43rd Symposium on Rock Mechanics, JSCE 129 -134 2015年01月
Evaluation of enzyme mediated calcite grouting as a possible soil improvement technique
D. Neupane, H. Yasuhara, N. Kinoshita Computer Methods and Recent Advances in Geomechanics 研究発表ペーパー・要旨（国際会議） 1169 -1172 2015年
This paper discusses the experimental and numerical work on Enzyme Mediated Calcite Precipitation, EMCP, technique along with the improved mechanical properties of sand achieved by employing this technique. The homogenous sand specimen having a diameter of 57 cm and a height of 60 cm is prepared inside a steel drum. Freshly prepared grout solution (urea-CaCl2 and urease) is injected at the centre of the sand specimen. Afterwards, the improved samples within the treated specimen is taken and subjected to the compressive strength tests. The calcite distribution throughout the specimen is also evaluated. A multi-component, fluid flow and geo-chemical transport simulator that can incorporate the precipitation reaction during the flow, is used to predict the calcite distribution. The experimental results are compared with the numerical predictions. The evaluated simulator can approximately predict the distribution of calcite within the sand specimen. The small amount of calcite precipitated within the soil mass appreciably improves the mechanical properties of sandy soil. The improved mechanical properties are enough to increase the resistance of soil against liquefaction.
Evaluation on the Healing of Single Rock Fracture under Thermal Conditions during Slide-hold-slide Process
Tsuda, N, Yasuhara, H, Yano, T, Kishida, K Proc. of the 27th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） G-6=8 2014年11月
Experimental Study on Structural Healing of Sedimentary Rock in Slide-Hold-Slide Type Triaxial process
Ohno, M, Yano, T, Yasuhara, H, Kikumoto, M, Kishida, K Proc. of the 27th KKHTCNN Symposium on Civil Engineering 研究発表ペーパー・要旨（国際会議） G-4-8 2014年11月
OPTIMIZATION OF TREATMENT AREA OF ENZYME MEDIATED CALCITE CEMENTATION: A NOVEL SOIL IMPROVEMENT TECHNIQUE
Debendra Neupane, Hideaki Yasuhara, Naoki Kinoshita Proc. Fourth International Conference on Geotechnique, Construction Materials and Environment 研究発表ペーパー・要旨（国際会議） 162 -166 2014年11月
Evolution of Permeability in Granite Fracture under High pH ConditionsEvolution of Permeability in Granite Fracture under High pH Conditions
H. Yasuhara, N. Kinoshita, K. Maeta, S. Nakashima, K. Kishida Proceedings of 8th Asian Rock Mechanics Symposium 研究発表ペーパー・要旨（国際会議） RW2-1 2014年10月
熱環境における岩石不連続面の連続透水・せん断実験
木下尚樹, 安原英明, 高橋学資源・素材講演集 1 (2) A4-3 2014年09月
凝灰岩の三軸せん断-保持-せん断試験と拘束圧による影響
大野正登, 矢野隆夫, 安原英明, 菊本統, 岸田潔第42回岩盤力学に関するシンポジウム講演集，(公)土木学会，pp. 337-342 2014年01月
加温条件下でのラフネスを有する不連続面のSlide-Hold-Slide試験とヒーリング現象
津田直弥, 矢野隆夫, 安原英明, 岸田潔第42回岩盤力学に関するシンポジウム講演集，(公)土木学会，pp. 331-336 2014年01月
力学‐化学連成数値モデルによるベレア砂岩透水性経時変化の再現解析
伊藤文, 安原英明, 木下尚樹, 高橋学岩盤力学に関するシンポジウム講演集(CD-ROM) 42nd ROMBUNNO.28 2014年
CO2地中貯留に起因する鉱物トラップが岩盤の力学・透水特性に与える影響
柏木亮太, 安原英明, 木下尚樹岩盤力学に関するシンポジウム講演集(CD-ROM) 研究発表ペーパー・要旨（全国大会，その他学術会議） 42nd ROMBUNNO.57 2014年
Evolution of mechanical and hydraulic properties in sandstone induced by mineral trapping
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida 48th US Rock Mechanics / Geomechanics Symposium 2014 研究発表ペーパー・要旨（国際会議） 1 134 -138 2014年01月
Copyright (2014) ARMA, American Rock Mechanics Association In this study, evolution of mechanical and hydraulic properties in Berea sandstone with initial porosity of 20 % is examined quantitatively by replicating mineral trapping process within pore spaces. The artificially accelerated mineral trapping is achieved by injecting a grout, resulting in calcite precipitation. The amount of calcite precipitated can be controlled by changing the concentrations of the grout and the total injection volume. The preliminary experiments indicate that the change of the mechanical and hydraulic properties is significant even if the calcite amount is relatively small - The values of Young's modulus/permeability increase/decrease with increase of the calcite amount. Specifically, the permeability decreases by one order of magnitude as the initial porosity of 20 % reduces to 18 %. This intense decrease of permeability may not be able to be replicated by existing numerical models, although distribution of the calcite precipitated within rock samples should be adequately examined because uniform distribution may not be achieved.
持続載荷による岩石不連続面の変形挙動に及ぼす熱・水・応力の影響
木下尚樹, 安原英明, 崎山久美子岩盤力学に関するシンポジウム講演論文集研究発表ペーパー・要旨（全国大会，その他学術会議） 42 325 -330 2014年01月
Long-term observation of rock permeability under high pressure and temperature conditions and its microstructural interpretation
H. Yasuhara, N. Kinoshita, M. Takahashi, S. Nakashima, K. Kishida 47th US Rock Mechanics / Geomechanics Symposium 2013 1 658 -663 2013年12月
A series of long-term permeability experiments using Berea Sandstone and Horonobe Mudstone has been conducted so as to understand the evolution of rock permeability under stressed and temperature-elevated conditions. The well-controlled experiments are carried out at confining pressures of 3.0-15 MPa and temperatures of 20 or 25 and 90°C. Flow-through experiments are conducted regularly (i.e., 5 or 10 day interval) to examine the evolution of rock permeability throughout the experiments - it should be noted that each experiment is kept always more than 500 days. Effluent concentrations are also measured for the ten elements of Si, Al, K, Fe, Ca, Na, Mg, Ti, S, and Cl that are included mainly in the targeted rocks. Rock samples were prepared for a SEM-EDX and/or a micro-focus X-ray CT to observe its microstructure. The SEM-EDX observation revealed that mineral dissolution dominates over mineral precipitation, and the micro-focus X-ray CT observation shows a slight increase in pore volume for the sandstone sample that has experienced long-term confining pressure and temperature. Copyright 2013 ARMA, American Rock Mechanics Association.
Soil Improvement Through Enzymatic Calcite Precipitation Technique: Small to Large Scale Experiments
Neupane D, Yasuhara H, Kinoshita N International Journal of Landslide and Environment 研究発表ペーパー・要旨（国際会議） 1 (1) 65 -66 2013年10月
Evaluation of Rock Permeability Alteration by Long-term Flow-through Experiments and by Microstructural Investigation
Hide Yasuhara, Manabu Takahashi, Naoki Kinoshita, Shinichiro Nakashima, Kiyoshi Kishida Proc. 6th Int. Symp. on In-Situ Rock Stress 研究発表ペーパー・要旨（国際会議） 288 -297 2013年08月
Slide-hold-slide型一面せん断試験における岩盤不連続面の形状変化と強度回復特性
青山太郎, 矢野隆夫, 中島伸一郎, 安原英明, 岸田潔第13回岩の力学国内シンポジウム＆第6回日韓ジョイントシンポジウム講演論文集，岩の力学連合会，pp. 243 – 247 2013年01月 [査読有り]
Evaluation of the enzymatic calcite precipitation technique to improve the physical and mechanical properties of sand
Debendra NEUPANE, Hideaki YASUHARA, Naoki KINOSHITA Proc. 13th Japan Symposium on Rock Mechanics & 6th Japan-Korea Joint Symposium on Rock Engineering 研究発表ペーパー・要旨（国際会議） 965 -968 2013年01月
温度・鉱物溶解条件を制御した持続載荷試験による花崗岩不連続面の変形挙動評価
崎山久美子, 木下尚樹, 安原英明, 川口隆岩の力学国内シンポジウム講演論文集(CD-ROM) 13th ROMBUNNO.79 2012年12月
拘束圧・温度制御下における堆積岩の長期透水試験
菊池紗帆, 安原英明, 木下尚樹, 高橋学岩の力学国内シンポジウム講演論文集(CD-ROM) 13th ROMBUNNO.78 2012年12月
動的解析による長支間ポケット式落石防護網の性能評価
木下尚樹, 安原英明, 矢田部龍一岩の力学国内シンポジウム講演論文集(CD-ROM) 13th ROMBUNNO.8 2012年12月
Healing and Shear Stress Reduction on Single Fracture of Rock Salt and Limestone under Slide-Hold-Slide Direct Shear Condition
Kishida, K, Yano, T, Yasuhara, H Abstract MR33A-2436 presented at 2012 Fall Meeting, AGU, San Francisco, Calif. 2012年12月
Long-term evolution of rock permeability in sandstone and mudstone under pressure- and temperature-controlled conditions
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida 46th US Rock Mechanics / Geomechanics Symposium 2012 3 2114 -2118 2012年12月
A suite of permeability experiments on intact rocks in sandstone and on a single fracture in siliceous mudstone has been conducted under confining pressures of 3-15 MPa, and at temperatures of 20-90°C for several hundred days in each experiment. For the mudstone experiments, oil-flow experiments are also conducted to examine the effect of mineral dissolution on the flow behavior - the oil-saturated condition refrains from the mineral dissolution and enables to certify if mechanical creep occurs under the stressed conditions. Evolution in permeability and dissolved mass fluxes were periodically measured to examine the flow behavior under stress and temperature conditions. In sandstone, the permeability of intact rocks little changed until a couple of hundred days, then started to increase with time. In mudstone, the permeability in a single fracture monotonically decreased with time and reached a quasi-steady state within one month. However, it started to increase with time after ?100 days. This augmentation in the permeability in sandstone and mudstone should be attributed to mineral dissolution within void spaces. Copyright 2012 ARMA, American Rock Mechanics Association.
The study on the method of determining the strength recovery in the Slide-Hold-Slide process under drained triaxial compression conditions
Araki, T, Yano, T, Yasuhara, H, Kishida, K Proc. of the 25th KKCNN Symposium on Civil Engineering, pp.275-278, Busan, Korea 2012年10月
Healing and shear stress reduction of rock salt single fracture under slide-hold-slide-direct shear experiments
Kishida, K, Yano, T, Yasuhara, H The Present and Future of Rock Engineering, ARMS7 2012年10月 [査読有り]
凝灰岩における加温条件下での三軸応力保持中の力学的特性に関する研究
荒木壯則, 矢野隆夫, 安原英明, 岸田潔第41回岩盤力学に関するシンポジウム講演集，(公)土木学会，pp. 220-225 2012年01月
Evolution of fracture permeability in granite under temperature, confining pressure and pH conditions prescribed
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida HARMONISING ROCK ENGINEERING AND THE ENVIRONMENT 1381 -1384 2012年
A suite of flow-through experiments in granite fracture is conducted under various temperature, confining pressure, and pH conditions, to examine the evolution of the fracture permeability. The well-controlled experiments are carried out at temperatures of 25 and 90 degrees C, confining pressures of 5 and 10MPa, and pH's of 7 and 11. At 25 degrees C, generally, the fracture permeability decreases with time and reaches a quasi-steady state within a few hundred hours. However, after the temperature is raised to 90 degrees C, the permeability again resumed decreasing throughout the rest of the experimental periods. The higher temperature, confining pressure, and pH are prescribed, the faster evolutions of the fracture permeability are observed. These results may indicate that the near-field rock mass of HLW may become safer with time in terms of solute transport behavior.
The study on deformation characteristics depending on temperature in tuff under drained triaxial compression conditions
Araki, T, Yano, T, Yasuhara, H, Kishida, K Proceedings of the twenty-fourth KKCNN Symposium on civil engineering, pp. 469 – 472 2011年12月
Long-term evolution in intact and fracture permeability in sandstone and mudstone under stress and temperature conditions
Yasuhara, H, Nakashima, S, Kishida, K Proceedings of the twenty-fourth KKCNN Symposium on civil engineering, pp. 389 – 392 2011年12月
Dependency of fracture geometry and spatial variation in pressure on hydraulic conductivity in rock fractures
Kishida, K, Hosoda, T, Sawada, A, Sato, H, Nakashima, S, Yasuhara H Harmonising Rock Engineering and the Environment, Qian &Zhou (eds), Taylor & Francis Group, ISBN 978-0-415-80444-8, 1327 – 1330 2011年10月 [査読有り]
Coupled Chemical and Mechanical Effects on Evolution of Rock Fracture Permeability
Hide Yasuhara, Naoki Kinoshita, Shinichiro Nakashima, Kiyoshi Kishida Proc. The 2011 World Congress on Advances in Structural Engineering and Mechanics (ASEM'11+) 3100 -3109 2011年09月
Slide-hold-slide experiments on sedimentary rock under drained triaxial stress conditions
Kishida, K, Araki, T, Yano, T, Yasuhara, H, Elsworth, D ARMA 11-418 2011年06月 [査読有り]
堆積岩による排水三軸せん断-保持-せん断試験
岸田潔, Elsworth, D, 矢野隆夫, 安原英明, 中島伸一郎第40回岩盤力学に関するシンポジウム講演集，pp. 173 – 178 2011年01月
生体触媒反応を介したセメンテーションによる改良砂の力学特性
鹿渡洸一, 林和幸, 木下尚樹, 安原英明岩盤力学に関するシンポジウム講演集(CD-ROM) 40th ROMBUNNO.35 2011年
温度・拘束圧の負荷期間に依存するベレア砂岩の透水力学特性の評価
鈴木崇史, 安原英明, 木下尚樹, 高橋学岩盤力学に関するシンポジウム講演集(CD-ROM) 40th ROMBUNNO.69 2011年
Evaluation of fracture permeability in granite influenced by stress and temperature
Hasegawa, D, Nakashima, S, Yasuhara, H, Kishida, K Proceedings of the twenty-third KKCNN Symposium on civil engineering, pp. 399 – 402 2010年12月
Stirred-flow-through experiments of granite under temperature and ph conditions controlled
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida 44th US Rock Mechanics Symposium - 5th US/Canada Rock Mechanics Symposium 2010年12月
A series of stirred-flow-through experiments using granite powder has been conduced under temperature and pH conditions controlled so as to evaluate the dissolution kinetics of the Mizunami granite. The well-controlled experiments are carried out at temperatures of 30-70°C, and pH 6-13, and a constant flow rate of the permeant fluid is set to be 0.1 mL/min. The system likely reaches a quasi-steady state roughly 100 hrs after the experiments get started. Effluent concentrations are measured by regular sampling for the seven elements of Si, Al, K, Fe, Ca, Na, and Mg that are included mainly in the targeted rock. Relatively high concentrations of Si, K and Ca are observed throughout the experiment. Generically, the higher temperature and pH are prescribed, the faster dissolution rates are evaluated. Subsequently, dissolution rate constants of the granite itself are evaluated using a typical Arrhenius equation and an extended formation taking into account the dependence of pH. Copyright 2010 ARMA, American Rock Mechanics Association.
Estimation of fracture aperture in granite using microfocus X-ray CT
Nakashima, S, Hasegawa, D, Yasuhara, H, Kishida, K EIT-JSCE Joint International Symposium on Engineering for Geo-Hazards: Earthquake and Landslides-for Surface and Subsurface Structures 2010年09月
Experimental study on shear strength recovery of single rock fracture through slide-hold-slide direct shear test and its modeling
Kishida, K, Kawaguchi, Y, Nakashima, S, Yasuhara, H ARMA 10-365 2010年06月 [査読有り]
Measurement of fracture aperture in granite core using microfocus X-ray CT
Nakashima, S, Hasegawa, D, Kishida, K, Yasuhara, H ARMA 10-205 2010年06月 [査読有り]
応力・温度が与える花崗岩不連続面の透水性への影響
長谷川大貴, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚第39回岩盤力学に関するシンポジウム講演集，土木学会，pp.267 – 270 2010年01月
マイクロフォーカスX線CTによる花崗岩の亀裂形状および開口幅の評価
中島伸一郎, 長谷川大貴, 安原英明, 岸田潔第39回岩盤力学に関するシンポジウム講演集，土木学会，pp.276 – 281 2010年01月
温度・pHを制御した花崗岩のフロースルー溶解試験
川下慧, 喜多亮太, 安原英明, 木下尚樹岩盤力学に関するシンポジウム講演集(CD-ROM) 39th ROMBUNNO.38 2010年
Stress- and Chemistry-Mediated Changes in the Hydraulic Property of Rock Fractures in Granite under Pressure- and Temperature-Prescribed Conditions
Yasuhara, H, Kinoshita, N, Nakashima, S, Kishida, K The 2009 Fall Meeting, H21C-0845, AGU 2009年12月
Evolution of Fracture Permeability in Granite and Its Evaluation via Coupled Chemo-Mechano Conceptual Model
H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida Proc. of 43rd US Rock Mech. Symp. CD 2009年11月
A coupled chemo-mechano conceptual model is presented to follow the evolution of fracture permeability observed in flow-through experiments in a single rock fracture in granite. The experiments are conducted under constant confining pressures of 5 and 10 MPa with differential water pressures ranging 0.01-0.5 MPa, and temperatures of 20 and 90°C. Permeability measured shows a monotonic decrease with time, via apparent steady state after relatively short periods at 20°C. A presented model addresses the two dissolution processes at contacting asperities and free walls within fractures, and also describes the multimineral dissolution behavior, showing a capability that the evolution of fracture aperture (or related permeability) may be followed with time under an arbitrary temperature and pressure conditions. Predictions utilizing the model proposed in this study show a relatively good agreement with the experimental measurements, although an abrupt reduction observed is incapable of being replicated, that is due to an unaccounted effect in the current model. Copyright 2009 ARMA, American Rock Mechanics Association.
Predicting temporal change of fracture permeability in granite via chemical-mechanical coupling model
Yasuhara, H, Nakashima, S, Kishida, K Proceedings of the 22nd KKCNN Symposium on Civil Engineering, pp. 433 – 438 2009年11月
岩盤不連続面におけるせん断挙動とその時間依存性の評価
川口雄大, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚資源・素材2009（札幌），企画発表・一般発表(A) (S)講演資料，地球・資源，pp. 43 – 46 2009年09月
Estimation of mechanical behavior during shear-holding process in single rock fracture under moderate stress
Kishida, K, Kawaguchi, Y, Nakashima, S, Yasuhara, H EIT-JSCE Joint International Symposium 2009, Geotechnical Infrastructure Asset Management, pp. 10 – 15 2009年09月
Evolution of Shear Strength and Permeability during Shear-holding in a Simulated Rock Fracture under Moderate Stress and Room Temperature Condition
Kawaguchi, Y, Nakashima, S, Kishida, K, Yasuhara, H, Yano, T, Hosoda, T ARMS 09-150 2009年06月 [査読有り]
三軸せん断過程における堆積軟岩の構造変化と透水性に関する実験的検討
河合祐輔, 中島伸一郎, 安原英明, 岸田潔第38回岩盤力学に関するシンポジウム講演集，土木学会，pp.287 – 290 2009年01月
岩盤不連続面のせん断透水試験と三乗則の適用性について
岸田潔, 中島伸一郎, 安原英明, 細田尚第38回岩盤力学に関するシンポジウム講演集，土木学会，pp. 260 – 265 2009年01月
花崗岩不連続面の透水実験―拘束圧・温度条件に起因する鉱物溶解の影響
重永三郎, 西山曜平, 木下尚樹, 安原英明岩盤力学に関するシンポジウム講演集(CD-ROM) 38th ROMBUNNO.45 2009年
A Study of Thermal Behavior of the Openings Effected by High Temperatures
N. Kinoshita, H. Yasuhara, Y. Inada Proceedings of The 12th International Conference of International Association for Computer Methods and Advances in Geomechanics 1 78 -83 2008年12月
The authors have proposed and discussed temporary storage of heated water in openings excavated in rock mountain from the viewpoints of multiple-utilization of land, environmental safeguards, energy conservation, etc. When used for heated-water storage, the rock mass around the openings will receive the effects of the heated water. In this study, a uniaxial compression creep test at high temperatures of the rock was also carried out, then the calculation of various constants on the creep was tried. Using the results obtained in this work, temperature and stress distribution around the openings when heated water were stored was analyzed by considering the creep properties. The thermal behavior and stability of the openings were also examined. The displacement of the openings was predicted to be 1.96 % of the diameter after one thousand days.
拘束圧および温度を制御した花崗岩不連続面の透水性経時変化の実験による検討
木下尚樹, 安原英明, 中島伸一郎, 岸田潔岩の力学国内シンポジウム講演論文集 12th(CD-ROM) ROMBUNNO.141 2008年09月 [査読有り]
不連続面の一面せん断試験における負荷状態保持の効果
川口雄大, 岸田潔, 中島伸一郎, 安原英明, 矢野隆夫, 細田尚岩の力学国内シンポジウム講演論文集 12th(CD-ROM) ROMBUNNO.123 2008年09月 [査読有り]
力学‐化学連成モデルによる花崗岩不連続面の透水挙動評価
安原英明, 木下尚樹, 中島伸一郎, 岸田潔岩の力学国内シンポジウム講演論文集 12th(CD-ROM) ROMBUNNO.142 2008年09月
拘束圧および温度を制御した花崗岩不連続面の透水性経時変化の実験による検討
木下尚樹, 安原英明, 中島伸一郎, 岸田潔岩の力学国内シンポジウム講演論文集 12th(CD-ROM) ROMBUNNO.141 2008年09月
Estimation of ground stability in considering groundwater and air bubbles using multiphase simulator
Kishida, K, Jacimovic, N, Hosoda, T, Nakashima, S, Kodaka, T, Yasuhara, H ARMS 08-250 2008年06月 [査読有り]
Experimental Study on the Permeability of Soft Rock During the Triaxial Shear Process
Kawai, Y, Kishida, K, Nakashima, S, Yasuhara, H ARMS 08-025 2008年06月 [査読有り]
堆積軟岩のダイレイタンシー特性が透水性に及ぼす影響について
河合祐輔, 中島伸一郎, 安原英明, 岸田潔第37回岩盤力学に関するシンポジウム講演集，土木学会，pp. 279-282 2008年01月
熱水環境下における岩盤空洞の熱挙動に関する一考察
木下尚樹, 安原英明岩盤力学に関するシンポジウム講演集(CD-ROM) 37th ROMBUNNO.63 2008年
サブクリティカル亀裂進展および圧力溶解を考慮した岩盤不連続面の圧縮挙動評価
安原英明, 木下尚樹, 中島伸一郎, 岸田潔岩盤力学に関するシンポジウム講演集(CD-ROM) 37th ROMBUNNO.48 2008年
Evolution of Permeability in Siliceous Rocks by Dissolution and Precipitation under Hydrothermal Conditions
H. Yasuhara, N. Kinoshita, H. Kurikami, S. Nakashima, K. Kishida Proceedings of the 3rd International Symposium GeoProc'2008 457 -464 2008年
気液二相流解析による空気注入時の地盤飽和度変化予測
森藤隆元, 安原英明, 岡村未対, 河内義範地盤工学研究発表会発表講演集 42nd 1079 -1080 2007年06月
圧力溶解現象を考慮した珪藻質岩石の透水性評価
安原英明, 操上広志, 木下尚樹, 岸田潔岩盤力学に関するシンポジウム講演集(CD-ROM) 36th ROMBUNNO.52 2007年

産業財産権: 特許第5599032号:地盤改良方法 2014年08月22日
安原英明, 林和幸国立大学法人愛媛大学 201403063749780417

受賞: 2020年05月岩の力学連合会 2019年度岩の力学連合会賞（論文賞）

受賞者: 緒方奨;安原英明;木下尚樹;岸田潔
2020年05月令和元年度土木学会四国支部研究・論文賞

受賞者: 安原英明他
2019年12月 The 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future Excellent Poster Award

受賞者: Takeru Kumagai, Hideaki Yasuhara, Naoki, Kinoshita, Sho Ogata
2019年01月第46回岩盤力学に関するシンポジウム，優秀講演論文賞

受賞者: 緒方奨;安原英明;岸田潔
2018年11月 The ISRM Franklin LectureAwarded by International Society for Rock Mechanics and Rock Engineering

受賞者: 安原英明
2018年09月 The Best Poster of Technical Program, The 6th Indonesia International Geothermal Convention & Exhibition (IIGCE) 2018

受賞者: 安原英明他
2018年05月平成29年度土木学会四国支部研究・論文賞

受賞者: 安原英明他
2016年06月平成27年度岩の力学連合会賞（論文賞）

受賞者: 安原英明他
2016年05月平成27年度土木学会四国支部研究・論文賞（2件受賞）

受賞者: 安原英明他
2016年01月第44回岩盤力学に関するシンポジウム優秀ポスター賞

受賞者: 安原英明他
2015年05月平成26年度土木学会四国支部研究・論文賞

受賞者: 安原英明他
2015年04月平成26年度地盤工学会四国支部研究・論文賞

受賞者: 安原英明他
2014年06月平成25年度地盤工学会論文賞（和文部門）

受賞者: 安原英明他
2013年08月平成25年度愛媛大学工学部教育貢献賞

受賞者: 安原英明他
2013年05月平成24年度土木学会四国支部研究・論文賞（2件受賞）

受賞者: 安原英明他
2012年06月平成23年度地盤工学会論文賞（和文部門）

受賞者: 安原英明他
2011年04月平成23年度文部科学大臣表彰若手科学者賞

受賞者: 安原英明
2010年05月平成21年度土木学会論文奨励賞

受賞者: 安原英明
2009年12月 Best Paper Award, International Symposium on Ground Improvement Technologies and Case Histories

受賞者: 安原英明他
2009年05月平成20年度岩の力学連合会賞（論文賞）

受賞者: 安原英明他
2009年01月第38回岩盤力学に関するシンポジウム優秀ポスター賞

受賞者: 安原英明他
2007年07月 Manuel Rocha Medal 2007

受賞者: 安原英明
2007年01月第36回岩盤力学に関するシンポジウム優秀講演論文集

受賞者: 安原英明他
2006年06月 2006 N.G.W. Cook Award for Ph.D. Thesis in Rock Mechanics

受賞者: 安原英明
共同研究・競争的資金等の研究課題

共同研究・競争的資金等の研究課題
岩盤の熱・水・応力・化学連成数値シミュレータの開発と地層処分技術への実装
文部科学省：科学研究補助金（基盤研究(B))
研究期間 : 2019年 -2022年
代表者 : 安原英明
地熱エネルギーの持続可能な開発を目的とした地熱流体の流れやすさの解明
（公財）中部電気利用基礎研究振興財団：創立30周年記念特別研究助成
研究期間 : 2019年 -2020年
代表者 : 安原英明
LPWA型無線ネットワークによる四国地域斜面災害監視システムの開発
（一社）四国クリエイト協会：技術開発・調査研究助成
研究期間 : 2018年 -2019年
代表者 : 安原英明
エチオピア特殊土地盤上道路災害低減に向けた植物由来の土壌改質剤の開発と運用モデル
科学技術振興機構：SATREPS
研究期間 : 2018年 -2019年
代表者 : 木村亮
環境問題に対処するトランスディシプリナリー研究・実践のための国際ネットワーク構築
日本学術振興会：研究拠点形成事業
研究期間 : 2018年 -2019年
代表者 : 榊原正幸
IoT向け無線通信ネットワーク技術を用いた四国全域の斜面災害監視システムの開発
（公財）セコム科学技術振興財団：特定領域研究助成
研究期間 : 2019年
代表者 : 安原英明
LPWA無線ネットワークによる斜面災害監視システムの開発
（公財）日立財団：2017年度・第49回倉田奨励金
研究期間 : 2018年 -2018年
代表者 : 安原英明
Study on influence of joint orientation on rock engineering properties for mining and infrastructure design
JICA：C-Best Project
研究期間 : 2017年 -2018年
代表者 : Dr. Purwanto
日本住宅のエクステリア工事に適した穴掘機の設計・試作
有限会社Ｃ．プランツ：
研究期間 : 2016年 -2018年
代表者 : 安原英明
年代効果等種々の影響を含む液状化強度の統一的解釈と新たな判定法の提案
文部科学省：科学研究費補助金（基盤研究(B)）
研究期間 : 2016年 -2018年
代表者 : 岡村未対
ヒマラヤ水系諸国における巨大災害に対する戦略的総合防災研究の展開
文部科学省：科学研究費補助金(基盤研究(B))
研究期間 : 2015年 -2018年
代表者 : 矢田部龍一
Constraining key factors that control the evolution of rock permeability under high temperature, stress and pH conditions
Korea Institute of Geoscience and Mineral Resources：
研究期間 : 2015年 -2017年
代表者 : 安原英明
熱・水・応力・化学連成場の岩盤透水・力学特性の解明と連成数値シミュレータの開発
文部科学省：科学研究費補助金(基盤研究(A))
研究期間 : 2014年 -2017年
代表者 : 安原英明
シェールオイル・ガス開発時のプロパント処理亀裂の長期透水挙動評価
（公財）岩谷直治記念財団：岩谷科学技術研究助成
研究期間 : 2016年 -2016年
代表者 : 安原英明
CO2地中貯留の堅牢性に及ぼす鉱物トラップの影響評価
（公財）中部電気利用基礎研究振興財団：
研究期間 : 2015年 -2015年
代表者 : 安原英明
シェールガス開発・地熱EGS適用を想定したプロパント処理岩盤き裂の透水特性の解明
文部科学省：科学研究費補助金(挑戦的萌芽研究)
研究期間 : 2013年 -2015年
代表者 : 安原英明

本研究では，水圧破砕時のプロパントの性能評価を目的とし，Ottawa sand，CARBOLITEを用いた透水試験を実施した．具体的には，Ottawa sand，CARBOLITE自体の粒状体供試体およびこれらのプロパントを幌延泥岩で挟んだ岩石挟持供試体を対象とし，拘束圧・温度制御下における等方圧保持・透水試験を実施し，透水性の経時変化を観察した．粒状体透水試験では，20℃条件において透過率の上下変動が見られたが，減少傾向は確認できなかった．90℃条件に移行した際には，1オーダー以上透過率が減少し再び透過率の上下変動が見られた．これより，Ottawa sandの温度変化による続成作用の促進が確認できた．Ottawa sandの岩石挟持透水試験では，20℃条件において透過率の大きな変化は見られなかったが，90℃条件では単調に減少している傾向が確認された．また，透水性変化に影響を及ぼす鉱物溶解等の地化学現象を，透過水の物質濃度を計測することで評価した．さらに粒状体透水試験では，等方圧保持・透水試験終了後のOttawa sandを用いて鉱物分析，微視構造分析を実施し，拘束圧，温度，鉱物溶解条件が供試体に与える影響について調査した．SEM画像では，実験後のOttawa sandに対して削れたような形跡や粒子表面に貫入後のような凹みが確認できた．これは，石英の溶解ステップおよび続成作用による粒子の相互貫入によるものと考えられ透過率低下の傍証と判断できる．またEDX観察では，SiとOが検出されX線回折分析の結果と調和的であった．最後に，圧力溶解モデルによる本実験の再現解析を実施し，解析モデルの有用性を検討すると共に，実験期間よりもより長期間の予察解析も行った．
コスト1/100の液状化対策工法の実現と一時的な酸化環境での化学・生物反応
文部科学省：科学研究費補助金(基盤研究(B))
研究期間 : 2013年 -2015年
代表者 : 岡村未対, 安原英明, 林和幸

空気の注入を実験的に模擬するためは，土の自重効果を正確に再現するできる遠心模型実験が特に有効である。そこで，本研究の模型実験は，全て遠心模型実験装置を用いて行った。遠心模型実験装置を用いて水平地盤に空気を注入し，その際の水圧分布，飽和度分布を測定することにより，空気注入中の水圧，サクション，飽和度の地盤内分布と注入圧の関係をある程度明らかにした。また注入前後に地盤表面沈下量の横断分布を2軸貫入装置を用いて連続的に測定し，数地点においてコーン貫入試験を行うことにより，貫入抵抗の変化から地盤のゆるみ領域とその発生条件についても確認した。さらに、遠心模型実験を対象とした気液二相流解析を行い，解析法の妥当性を確認した。NEXCO西日本の現場において、盛土直下地盤に空気を注入する実証実験の現場において連続コアサンプリングを行い試料を採取し（GL-5-15m）保水性試験を行って地盤の保水性を明らかにた。これを元に，気液二相流解析を行い，実証実験の事前予測を行い，現場実験での合理的な注入管配置や注入方法，注入緒元を検討した。不飽和砂質土のせん断特性と不飽和化した地盤の耐震性水平地盤及び盛土直下の液状化層を部分的に不飽和化した地盤の動的遠心模型実験を行い，飽和－不飽和の境界領域での水圧相互作用を調べた。また，有効応力解析を行い，実験結果と併せて飽和－不飽和境界領域での水圧の相互作用を検討した。飽和度が85-95%の封入不飽和状態にある砂質土の非排水三軸試験を行い，非排水強度特性に及ぼす飽和度の影響を調べた。正のダイレタンシーを発現する中密の供試体を用い，溶存する気体の種類の影響についても調べた。一次元のカラム試験機を分割型にすることにより、地盤中の飽和度変化を詳細に計測できる装置を作成し，これを用いて領域中で溶解する気体量を測定した。
防災研究と防災教育を核としたヒマラヤ水系諸国における総合防災研究の展開
文部科学省：科学研究費補助金(基盤研究(B))
研究期間 : 2012年 -2014年
代表者 : 矢田部龍一, 板屋英治, 安原英明, N.P Bhandary, 長谷川修一

昨年度に収集した各種の収集データや調査データなどをもとに地すべりやカトマンズ盆地のち地下水GISデータベースを構築した。カトマンズ盆地の水収支の経年変化について、地下水位の現地観測結果や既存の各種観測データを用いて整理し、検討を行った。また、水質の経年変化について現地調査結果や既存の観測データを元に詳細な整理と解析を行った。これらの各種のデータを元に、カトマンズ盆地の水資源と水環境に関わるGISデータベースを構築した。次いで、構築したGISデータベースを用いて、カトマンズ盆地の帯水層の脆弱性評価を行った。評価には3つのモデルを用いた。一つは、広く活用されているDRASTICモデルである。それ以外に、このモデルを改良した2つのモデルを提案し、その妥当性を検討している。提案したモデルはGIS解析を基にした2層ファジーパターン認識モデルと、もう一つはGIS環境を用いたファジールールによるモデルである。研究成果は論文として公表した。また、ネパールにおけるソフトな地震防災対策の総合的な構築と実施、そして効果の評価を行った。具体的には、地域ならびに学校防災教育の展開、家屋の耐震補強法の開発と全国的普及、ネパール政府やUNDPなどと連携したネパール政府防災計画の策定について検討した。これらの研究成果は論文として公表した。その他、ネパールの地すべりや地震ハザードの解析を行い、論文として公表した。
圧力・化学反応による岩盤不連続面の凹凸構造の経年変化を考慮した物質移行性の評価
文部科学省：科学研究費補助金(基盤研究(C))
研究期間 : 2012年 -2014年
代表者 : 岸田潔, 澤田淳, 安原英明

本研究は，エネルギー生成後の副産物である放射性廃棄物の地層処分事業の安全性能評価のための基礎となる種々の応力・温度条件下での単一不連続面の水理学特性および力学特性を解明し，物質移行パラメータの同定（温度-化学-水理連成モデルの構築）およびヒーリング現象を包含した力学モデル（温度-化学-力学連成モデル）の構築を目指すものである．今年度の主な研究成果は，以下のとおりです．「不連続面の形状計測と温度-化学連成による不連続面構造評価モデルの構築」では，対象とした岩塩供試体の不連続面の計測をレーザー変位計で行い，繰返しSHS型一面せん断試験を実施した．岩塩は透明度が高く，一方，繰返しせん断試験に用いることでマイクロクラックなどが生じ，レーザーでの計測が困難であったが，計測表面をコーティングすることにより，計測を可能とした．SHS型一面せん断試験の結果と併せて，せん断および応力保持による不連続面構造の変化とヒーリング現象に関する検討を行った．また，加温実験に関しては，速度・状態依存摩擦則の適用を試み，加温による強度回復の影響について検討を行った．「透水挙動の評価と物質移行パラメータの同定」では，接触した状態での花崗岩不連続面の形状と開口幅分布の抽出をマイクロフォーカスX線CTで行い，それらの情報を用いて浸透シミュレーションを実施した．「SHS型せん断-透水試験の実施とヒーリング現象を考慮した力学挙動モデルの構築」では，保持に伴う強度回復は構造回復に起因するものであると考え，修正Cam Clayモデルに状態変数を導入して，ヒーリング現象のシミュレーションを行った．Deiterichの対数線形モデルと関連付けて試解析を行い，強度回復を表現することが可能となった．
熱・水・応力・化学連成環境における岩盤透水特性の解明と連成モデルの高度化
文部科学省：科学研究費補助金(基盤研究(B))
研究期間 : 2011年 -2014年
代表者 : 安原英明

高レベル放射性廃棄物等のエネルギー生成後の副産物を深地層下の岩盤内に隔離し，長期に渡りその性能を保証するためには，副産物隔離後の岩盤の水理学特性の経時変化を予測評価することが必要不可欠である．そこで本研究では,透水特性の経時変化に着目し，拘束圧及び温度を制御した単一の亀裂を有する花崗岩，砂岩および泥岩の透水試験を実施し，透水特性の経時変化を観察すると共に，その変化に起因するメカニズムの解明を試みた．実験条件は，拘束圧3.0，5.0，7.5，15.0MPaで，また温度条件は20および90℃で透水実験を行った．さらに，透過水については蒸留水，高pH水および不溶性のシリコーンオイルの3種類を採用した．蒸留水については，鉱物溶解を促進させるために使用し，高pH水は，人工バリアのセメント溶出を模擬した．また，シリコーンオイルについては，逆に鉱物溶解を起こさせない環境を模擬するために使用した．透水試験の結果，蒸留水を使用した場合，実験開始と共に透水性は一様に低下していくことが確認された．一方，高pH水を使用した実験では，20℃条件では，ほとんど透水性の変化が確認されなかったが，90℃条件では，蒸留水を用いた実験よりも透水性が低下する結果が得られた．また，鉱物分析及び微視構造観察の結果より，石英表面の溶解や，透過流体中のカルシウムとケイ素の溶出に起因するCSHの沈殿が確認された．さらに，物質濃度評価の結果より，25および90℃条件共に，中性条件と比較してより高いSi濃度が検出された．これは，高pH条件の透過流体が中性条件よりも岩石構成鉱物の石英や長石をより多く溶解させていることに起因している．その結果，90℃条件では透過率が大きく減少したと考えられる．
生体触媒型グラウト材注入工法の開発
（公財）前田記念工学振興財団：
研究期間 : 2013年 -2013年
代表者 : 安原英明
現場適用を想定した生体触媒型グラウト技術の高度化
（社）四国建設弘済会：
研究期間 : 2013年 -2013年
代表者 : 安原英明
地震時液状化リスク低減を目的とした親環境バイオグラウトの開発
（財）山陽放送学術文化財団：
研究期間 : 2012年 -2012年
代表者 : 安原英明
地震時液状化対策を想定したウレアーゼ型バイオグラウトの開発
（独）科学技術振興機構：
研究期間 : 2011年 -2012年
代表者 : 安原英明
温度・拘束圧制御下における珪質岩石の透水・物質輸送特性の評価と連成モデルの開発
（財）原子力環境整備促進･資金管理センター：
研究期間 : 2010年 -2012年
代表者 : 安原英明
空気注入による格段に安価な液状化対策工法の確立と地盤内環境への影響
文部科学省：科学研究費補助金(基盤研究(B))
研究期間 : 2009年 -2012年
代表者 : 岡村未対, 安原英明

本研究では、地盤中に直接空気を注入し地盤を不飽和化することによる格段に安価な液状化対策法を確立し、設計法を提案することを目的とした。そのために、現状でネックとなっている以下の要素技術課題の解決を図った。(1) 空気注入時の地盤および構造物の変状メカニズムの解明と合理的な注入方法の検討(2) 不飽和化による液状化対策効果の発現メカニズム(3) 不飽和化による液状化強度増加率が土の体積ひずみポテンシャルによりユニークに評価できることを砂以外にもシルトについても明らかにした。(4) 研究成果を取りまとめ,地盤の不飽和による液状化対策工法の設計施工マニュアルを作成し公開した。
地震時地盤災害リスク低減と地盤環境保護に効果のあるバイオグラウトの開発研究
（公財）住友財団：
研究期間 : 2011年 -2011年
代表者 : 安原英明
温度圧力環境下における結晶質岩不連続面の透水性経時変化のメカニズム解明
文部科学省：科学研究費補助金(基盤研究(C))
研究期間 : 2009年 -2011年
代表者 : 木下尚樹, 安原英明

本研究では,温度・拘束圧を制御し,結晶質岩である花崗岩不連続面の透水実験を実施し,透水特性の経時変化に及ぼす影響を定量評価した.特に透過水のpH(鉱物溶解条件)および不連続面形状が及ぼす影響について検討した.また,透過水への溶出物質の定量分析,不連続面のSEM観察, EDX分析により不連続面の微視構造の変化を把握し,メカニズムを考察した.
地盤改良を想定した親環境バイオグラウト技術の開発
（社）四国建設弘済会：
研究期間 : 2010年 -2010年
代表者 : 安原英明
微生物代謝を活用した親環境地盤改良技術（バイオグラウト）の開発
（財）発酵研究所：
研究期間 : 2010年 -2010年
代表者 : 安原英明
化学反応を考慮した多相流シミュレータの開発とエアスパージングへの適用
文部科学省：科学研究費補助金(基盤研究(C))
研究期間 : 2008年 -2010年
代表者 : 岸田潔, 細田尚, 中島伸一郎, 安原英明, 音田慎一郎, 川端淳一

本研究は,汚染物質の移流,CO2地下貯留,エアスパージング等,地下での多相流挙動をシミュレーションするためのモデルの構築を行った.提案するモデルは,気相・液相の動的挙動を表現することができる.また,液相は二つのコンポーネント,気相を接する動かない液相と移動する液相,に分割して考える.これにより,地下水での物質の移行をシミュレーションすることが可能となった.また,温度による相変化を組み入れ,地下水中の溶存酸素析出過程を再現した
応力・温度に依存する岩盤の化学現象の解明と連成モデルの構築
文部科学省：科学研究費補助金(若手研究(B))
研究期間 : 2008年 -2009年
代表者 : 安原英明

本研究では,岩盤の透水特性に着目し,拘束圧及び温度を制御した単一の亀裂を有する花崗岩の透水試験を実施し,透水特性の経時変化を観察すると共に,その変化に起因するメカニズムの解明を試みた.その結果,透水特性の変化は,作用する応力と温度に大きく依存し,90℃程度の温度条件でもその影響は大きいことが確認された.また,構築した解析モデルの有用性を確認した.

免許資格

担当授業科目: 教育活動(B)
担当授業科目(B01)
2019, 前期, 学部, 土質力学Ⅰ及び同演習
2019, 前期, 学部, 建設倫理
2019, 前期, 学部, 環境建設デザイン演習

その他: 2018年09月 - 現在愛媛県建設工事総合評価審査委員委員
2018年 - 現在日本地下石油備蓄株式会社保全技術検討委員会委員
2018年 - 現在地盤工学会地盤工学ジャーナル編集委員会委員
2018年 - 現在土木学会岩盤力学委員会委員兼幹事
2017年 - 現在経済産業省中国四国産業保安監督部地方鉱山保安協議会委員
2016年 - 現在国土交通省四国地方整備局道路防災有識者
2013年 - 現在岩の力学連合会RockNet委員会委員
2011年04月 - 現在地盤工学会四国支部幹事
2011年 - 現在岩の力学連合会国際技術委員会委員
2011年 - 現在地盤工学会調査・研究部会岩盤工学企画委員会委員
2007年 - 現在岩の力学連合会電子ジャーナル委員会委員
2010年 - 2019年03月資源・素材学会Journal of MMIJ編集委員会編集委員
2015年 - 2017年03月岩の力学連合会RockNet委員会委員長
2015年 - 2017年03月土木学会論文集編集員会委員
2016年07月 - 2017年土木学会四国支部 H28年度インターネット活用委員会委員
2016年07月 - 2017年土木学会四国支部 H28年度土木学会四国支部地域貢献事業運営委員会委員
2011年06月 - 2016年05月地盤工学会Soils and Foundations編集委員
2011年 - 2016年03月土木学会岩盤タンクの健全性評価技術に関する調査検討小委員会幹事委員
2013年 - 2015年土木学会四国支部幹事
2007年 - 2015年土木学会岩盤力学委員会論文小委員会委員
2007年 - 2011年03月岩の力学連合会海外連絡委員会委員
2008年 - 2010年地盤工学会調査・研究部会委員
2007年 - 2010年地盤工学会四国支部地域地盤問題研究委員会委員
2006年04月 - 2009年03月地盤工学会IT推進委員会四国支部連絡委員
2006年04月 - 2009年03月土木学会岩盤力学委員会先端岩盤計測小委員会委員
2007年 - 2008年09月岩の力学連合会岩の力学国内シンポジウム運営委員会委員

安原英明（ヤスハラヒデアキ）Researcers Profile