| Project/Area Number |
06452289
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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 |
Building structures/materials
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| Research Institution | Nippon Institute of Technology |
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Principal Investigator |
KUWABARA Fumio Nippon Institute of Technology, Department of Architecture, Professor, 工学部, 教授 (60101200)
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| Co-Investigator(Kenkyū-buntansha) |
田中 実 建築技術研究センター, 教育技術員 (90245184)
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| Project Period (FY) |
1994 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥5,100,000 (Direct Cost: ¥5,100,000)
Fiscal Year 1996: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | Model Test / Pile / Vertical Load / Load Test / Friction / Earth Pressure |
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| Research Abstract |
A number of vertical load tests of an instrumented model pile are performed in a clay soil deposit at a field to investigate the performance of the shaft friction. A35.7mm diameter closed ended steel tubular pile is jacked into a over-consolidated clay layr at a rate of the range from 0.01 to 10 mm/s. The instrument, which included redial stress, shear stress, pore-pressure and axial load sensors, are monitored continuously during the penetration at the different distance from the pile tip. The results show that the yield shear stress on the shaft increases as the increase of the penetration rate and that the shaft friction does not affected by the distance from the pile tip.
Direct shear tests between the pile material (concrete) and clay soil are carried out to investigate the effects of the volume change characteristics of surrounding soil on the shaft friction. Two different conditions are conducted during the test ; constant pressure and constant volume (undrained condition). Excess pore water pressure is measured at the interface by a sensor which is buried in the concrete specimen. The results show that under the constant volume condition the shear strength decreases as the increase of shear rate beause of the generation of pore pressure, while under the constant volume condition the shear strength is constant within the range of shear rates.
The volume change characteristic under direct shear tests explains the pile load test results, e.g.the increase of shaft friction at fast shear. It is thought that the characteristic of soil dilatancy under shear force plays an essential role to determine the effects of shear rate on the shaft friction on piles
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