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.