| Project/Area Number |
14350252
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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 | The University of Tokyo |
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Principal Investigator |
KOSEKI Junichi The University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (30272511)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Takeshi The University of Tokyo, Institute of Industrial Science, Research Associate, 生産技術研究所, 助手 (30092224)
HONDA Tsuyoshi The University of Tokyo, Graduate School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (30323512)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2003: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2002: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Torsional shear tests / Sand / Local deformation measurement / Young's modulus / Poisson's ratio / Shear modulus / End restraint / Bedding error |
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| Research Abstract |
In seismic response analyses based on equivalent linear elastic modeling that are frequently employed in practice, cyclic deformation properties of geomaterials need to be evaluated accurately. Since level ground is subjected to cyclic shear stress acting on horizontal-vertical planes during earthquakes, it is more appropriate to use torsional shear tests on hollow cylindrical specimens than to use conventional triaxial tests on solid cylindrical specimens in simulating such stress conditions in the laboratory.
In view of the above, in order to improve the accuracy of evaluating cyclic deformation properties, the quasi-elastic deformation properties of dry, dense Toyoura sand at very small strain level were investigated by conducting a series of triaxial and torsional shear tests on hollow cylindrical specimens. Strains were measured locally by a newly developed pin-typed local deformation transducer.
In the tests, effect of end-restraint at the top cap and pedestal on small strain shear modulus that was measured externally by applying small unload/reload cycles in the torsional direction was found to be significant. Similar tendency was observed in the other tests conducted by changing the density and the soil gradation.
A new hypo-elastic model was proposed to simulate the inherent and stress-induced anisotropies of quasi-elastic deformation properties of sand, considering rotation of principal stress axes from material axes. Good agreements between experimental and simulation data were observed. In the simulation, effect of inherent anisotropy on the quasi-elastic deformation properties of Toyoura sand was found to be small.
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