地震作用下饱和土-桩-上部结构动力相互作用研究

将土体视为液固两相多孔介质，利用连续介质力学得到了饱和土层的水平动力阻抗，将上部结构视为梁单元，桩-饱和土-桩之间的动力相互作用借助于等效的Winkler动力弹簧和波的干涉来模拟，并通过承台处力的平衡将群桩和上部结构耦合起来，研究了简谐SH地震波作用下饱和土-桩-上部结构的动力相互作用问题。以2×2群桩为例，对饱和土-桩-上部结构体系进行了数值分析，讨论有关参数对结构体系动力特性特别是抗震性能的影响。数值分析表明，桩间距、桩-土弹性模量比、长径比等对结构体系的抗震性能有较大影响。桩间距对地震放大系数的影响与外界激励的频率有关，桩土模量比较小、结构和桩基的阻尼较大时结构体系的抗震效果较好，长径比越大地震作用下产生的结构变形越大

Dynamic interaction of saturated soil-pile-structure system under seismic loading

The soil around the pile is regarded as saturated porous medium;and the horizontal dynamic impedance of saturated soil is obtained by using continuum mechanics;and the pile-saturated soil-pile interaction is modeled with dynamic Winkler spring and wave-interference by regarding the superstructure as a beam model;through the force equilibrium at the pile cap level,the pile groups and the structure were coupled;and dynamic interaction of saturated soil-pile-structure under harmonic SH wave is also investigated.The simplest case of a 2×2 pile group is formulated;and the effect of the structural parameters on the dynamic behaviors is analyzed;especially studied the seismic properties of the saturated soil-pile structure system.Numerical calculations show that the pile spacing,length-diameter ratio,ratio of modulus between pile and soil had great effect on the dynamic behaviors of coupled system of saturated soil-pile.The influence of pile spacing on earthquake amplification coefficient is concerned with external excitation frequency;the aseismic effect is better when the ratio of modulus between pile and soil is smaller and the damping of structure and pile is larger;and the greater the length-diameter ratio,the greater the structural deformation produced by seismic action.