Study on a Method to Simulate a Soil-Pile Foundation System

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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.