| Project/Area Number |
02302062
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
基礎・土質工学
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| Research Institution | Saitama University |
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Principal Investigator |
ODA M. Saitama UNI. Found, ENG., Professor, 工学部, 教授 (90008855)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIZUKA Y. Shimizu CO., Reseach INSTi., Chief Engineer, 技術研究所, 主任研究員
IWASHITA Y. Saitama UNI., Found. ENG., Lecturer, 工学部, 講師 (40203377)
YAMABE T. Saitama UNI., Found. ENG., Asso. Professor, 工学部, 助教授 (40125894)
KISHINO Y. Touhoku UNI., Civil ENG., Asso. Professor, 工学部, 助教授 (00005448)
TATSUOKA F. UNI. of Tokyo, Inst. of IND SCI., Professor, 生産技術研究所, 教授 (70111565)
TANAKA T. Meiji UNI., Agricul. ENG., Professor (70167500)
KYOYA T. Nagoya UNI., Civil ENG., Assistant (00186347)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Shear plane / Strain softening / Strain localization / Geological discontinuities / Equivalent continuum / Bearing capacity / Numerical analysis |
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| Research Abstract |
Soils are consist of discrete particles, and fail along discontinuous planes where shear deformation is localized. Also, rock masses are cut by geological discontinuities, such as joints and faults. This research was organized to make it clear the mechanical problems related to these discontinuous geological materials. Special emphasis was placed on 1) micro-mechanism of shear localization, 2) numerical simulation of shear band formation and 3) continuum model hydro-mechanically equivalent to discontinuous geological materials, with the following conclusions :
1) According to the plane strain tests on sand, with an equipment for measuring the micro-distribution of strain, localization starts a little before the peak stress is mobilized. Orientation of shear bands depends not only on the applied stress condition, but on the direction of stress with respect to the anisotropy axis of sand. The width of shear bands is 10 to 15 times larger than the mean size of particle diameters. Micro-structure of shear bands. with curvature, appeals an important role of couple stress in their formation.
2) Numerical simulation is a powerful tool to see what happens inside the shear bands. Such analyses have shown that particle rotation is an important micromechanism of deformation, which also implies the presence of couple stress.
3) Tensors, called the crack tensor and the damage tensor, are used as internal variables showing the structural characteristics of geological discontinuities in the formulation of equivalent continuum. That is, permeability tensor, elastic compliance tensor and plastic yield function are formulated in terms of these tensors.
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