| Project/Area Number |
13650539
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Shinshu University |
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Principal Investigator |
KONISHI Junichi Shinshu University, the department of technology, assistant professor, 工学部, 助教授 (60021002)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | unsaturated soils / suction / method of making specimens / shear strength / triaxial test / unconfined compression test / water retention characteristics / 供試体作成方法 |
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| Research Abstract |
A technique for making unsaturated soil samples using pressure membrane method are developed. Advantages and limitations of this method are discussed. The membrane filter selected and used is a cellulose acetate type filter of 0.2 μm pore size and of 0.125 μm thick. The air entry value of the filter is 24kPa.
For a pressure range more than the air entry value of the filter, the water retention curves for dehydration obtained by the pressure membrane method seem to coincide with those obtained by pressure plate method.
In the pressure membrane method, only small absorption occurs when the applied pressure is released. This property may enable us to make samples without absorption of water even when the pressure is released.
The pressure membrane method is better than the compaction method for making a loose sample.
Initial suction of the trimmed specimens is lower than the applied pore air pressure when the samples are made by the pressure membrane method. To make samples with a suction, higher pore air pressure than the suction should be applied.
Triaxial compression tests under constant pore air pressure in undrained condition were carried out for unsaturated soil. The suction may have a quasi-overconsolidated effect on the saturated samples with the suction histories.
The apparent cohesion increase proportionally with suction, whereas the internal friction angle seems to have a constant value since the inclination of the failure line does not change with the air pressure value and the higher the air pressure, the larger the intercept of the failure line.
In unconfined compression tests of unsaturated soils, volume change may occur. Higher the suction of the specimen, the higher the dilation of it.
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