| Project/Area Number |
12450187
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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 |
Geotechnical engineering
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| Research Institution | Saitama University |
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Principal Investigator |
ODA Masanobu Saitama Univer., Dept. Civil & Environ. Engrg, Prof., 工学部, 教授 (90008855)
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| Co-Investigator(Kenkyū-buntansha) |
NAKASE Hitoshi Tokyo Electric Power Services Comp. Limited, Research Leader, 技術開発部, 課長(研究職)
IWASHITA Kazuyoshi Saitama Univ., Dept. Civil & Environ. Engrg, Assoc. Prof., 工学部, 助教授 (40203377)
SUZUKI Kiichi Saitama Univ., Dept. Civil & Environ. Engrg, Assoc. Prof., 工学部, 助教授 (70282423)
KAWAMOTO Ken Saitama Univ., Dept, Civil & Environ. Engng, Res. Assistant., 工学部, 助手 (50292644)
KAZAMA Hidehiko Saitama Univ., Dept. Civil & Environ. Engrg, Assoc. Prof.., 地圏科学研究センター, 助教授 (40008868)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥7,800,000 (Direct Cost: ¥7,800,000)
Fiscal Year 2002: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2001: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2000: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | Liquefaction / Numerical simulation / Undrained cyclic triaxial test / Micro-structure of soil / Anisotropy / Collapse caused by seepage force |
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| Research Abstract |
Our research objectives are first to develop a program based on Distinct Element Method (DEM), which makes it possible to numerically simulate the liquefaction phenomenon ; second to figure out liquefaction mechanism from micro-mechanical point of view ; and finally, to verify experimentally the reality of numerical simulation results. We obtained the following results :
1) DEM is programmed such that the interaction between particles and surrounding water can be taken into account. It can successfully be applied to liquefaction associated upward seepage flow.
2) Numerical simulation tests were carried out using the distinct element method (DEM) by paying much attention to the micro-deformation mechanism during liquefaction of saturated granular materials. During the cyclic loading, column-like structures are generated in the corresponding direction of major principal stress. The microstructure becomes more anisotropic with cyclic loading. Not only decrease of effective stress but also anisotropy of the microstructure itself accelerate the anisotropy of microstructure. Such anisotropic structure becomes unstable and finally collapses when the major principal stress rotates.
3) Undrained cyclic triaxial tests are carried out to clarify the effect of microstructure on liquefaction. Following facts are of particular interest. Voids, randomly distributed at first, are connected in series between the column-like structures. The excess pore water pressure increases markedly under undrained cyclic loading, in particular, when the connected voids are stressed perpendicular to their elongation direction. This is the reason why once liquefied sand loses sharply the liquefaction resistance in a subsequent re-liquefaction test.
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