2002 Fiscal Year Final Research Report Summary
Physicochemical and and hydromechanical behaviors of clay sulfate rocks and soils -Application study for sealing systems of underground waste repository -
| Project/Area Number |
12450413
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | UNIVERSITY OF TOKYO |
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Principal Investigator |
YAMATOMI Jiro The University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (70107548)
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| Co-Investigator(Kenkyū-buntansha) |
ADACHI Tsuyoshi The University of Tokyo, School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (40262050)
MOGI Gento The University of Tokyo, School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (70182160)
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| Project Period (FY) |
2000 – 2002
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| Keywords | swelling / swelling clay / underground waste repository / finite element analysis / mathematical modeling / constitutive relations / hydromechanical coupling / underground seepage flow |
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| Research Abstract |
The modeling of swelling behavior is a necessary step to evaluate swelling minerals as sealing materials and to design underground waste repository. The purpose of the study is to construct a mathematical model to describe the swelling behaviors of clay minerals and to develop a new FEM program in which a coupled hydromechanical procedure is incorporated to analyze stresses, displacements, water uptakes, and volumetric expansions/pressure build-ups in swelling geological materials. Through the sensitivity analysis on the model of swelling behaviors constructed on the basis of the coupled-hydromechanical procedure, the influence of several important parameters involved in the formulae of elastic modulus, water retention curve, hydraulic conductivity and/or diffusivity, was discussed.
Additionally, the method to identify the nonlinear hydromechanical tangent moduli of swelling clay was clarified, in which transversely isotropic behavior of hydromechanical coupling has been incorporated, b
… More
ased on the experimental results obtained by free swelling tests. The experimental results of constant load swelling tests in uniaxial strain condition and free swelling tests were discussed. We find that swelling behaviors such as changes of void ratio, water content ratio, and saturation depend strongly on stress level and/or constrained conditions, and verify the predicted swelling behaviors in uniaxial and free conditions by using finite element analysis.
The hydromechanics of seepage flows through fractures within rock mass, where a waste repository is situated, must be clarified, since the rock mass can be expected as second and natural absorbents surrounding an artificial barrier composed of swelling day. Therefore, modeling the seepage flows through rock fractures can be regarded as crucial for achieving and evaluating overall stability of an underground repository and sealing systems. In the present study, we have studied groundwater flow through a single rock fracture, which is possible to be partially closed under high rock stresses. The flow rule must be different from the cubic one of a panel plate model and it must show the tortuosity. Based on a theoretical work, we have proposed a non-cubic flow rule, which can be applicable to partially closed rock fractures. Less
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Research Products
(4 results)
