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Abstract By conducting dynamic centrifuge model tests on the clay-pile-raft system，this paper investigated that a kind of dynamic interaction non-coincidence between soil and pile-raft foundation. This suggested that soil motion can not be representative of foundation motion，and that adopting free field soil seismic parameters directly as foundation parameters in traditional building aseismic design is unreasonable；differences on the acceleration time histories，response spectra，as well as resonance period between soil and pile-raft foundation are very obvious and can not be neglected in engineering aseismic design. The effects of modulus reduction and stiffness degradation are manifested as an increase in the resonance periods of the clay layers with the level of shaking and with successive earthquakes，while this is not the case for the pile-raft foundation since its resonance period is hardly affected by earthquake loadings. Furthermore，raft period is always lower than corresponding clay period and period of far field clay is lower than that of near field clay because of remolding softening effect under the same condition，and pile-raft dynamic behavior is hardly affected by the stiffness degradation of surrounding clay.
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Received: 03 December 2010
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2011, Vol. 30 
