| Project/Area Number |
60850108
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | Kobe University |
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Principal Investigator |
MIZUHATA Koji Faculty of Engineering, Kobe University, Professor, 工学部, 教授 (20031065)
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| Co-Investigator(Kenkyū-buntansha) |
MAEDA Yukinori Faculty of Engineering, Kobe University, Research Associate, 工学部, 助手 (00116253)
KUSAKABE Kaoru Faculty of Engineering, Kobe University, Associate Professor, 工学部, 助教授 (80027250)
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| Project Period (FY) |
1985 – 1987
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥9,800,000 (Direct Cost: ¥9,800,000)
Fiscal Year 1987: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1986: ¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1985: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Keywords | Soil-Pile Foundation System / Vibration Generator Test / Impulse Test / Softer Zone / Gap around the Pile / Pile Groups / Dynamic Axial Strain / 薄層要素法 / 杭基礎 / 群杭基礎 / 起振機 / 振動実験 / 杭基礎のモデル化 / 杭周地盤の剛性低下 / 杭周地盤の剥離 |
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| Research Abstract |
A purpose of this project is to propose a reasonable model of the soil-pile foundation system, based on the analytical and experimental studies. As the experimental studies, the vibration tests of full scale steel and concrete piles with a concrete block at their tops due to vertical and horizontal harmonic excitations have been conducted by making use of a vibration generator. Following results are obtained.
1. The larger the eccentric moment of the vibration generator, the lower the resonance frequency of the soil-pile foundation system.
2. The consentraite condition of the pile top, which is free or fixed, effects on the stiffness coefficient and viscous damping coefficient of the soil-pile foundation system.
3. In the vertical excitation, dynamic axial strain of the pile exists even deeper region, but in the horizontal excitation, it vanishes at deeper region. And it seems that gap between the pile and its surrounding soil ground occurs in the vicinity of the ground surface.
4. Fourier spectrum of response of pile foundation due to impulseexcitation is similar to its amplitude characteristics obtained from the vibration generator test. Then impulse test of the soil-pile foundation system is available. From the analytical study on vibration characteristics of the pile-softer zonesoil system, following results are followed.
5. The lower the stiffness of the softer zone, the lower the resonance frequency of the soil-pile interacion system, and the deeper the gap around the pile, the greater the resonance amplitude.
6. The reduction of the stiffness of softer zone and the existance of gap around the pile must be considerd for every kind of piles. As the result of their studies, ti is pointed out that the pile-softer zone-soil system with gap around the pile is the best analytical model.
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