层状土介质中群桩及其上部结构体系对任意入射地震波的响应

RESPONSE OF PILE GROUP EMBEDDED IN A LAYERED SOIL-SUPERSTRUCTURE INTERACTION SYSTEM TO ARBITRARY INCIDENT SEISMIC WAVES

本文舍弃桩基动力分析中的土介质平面应变假定,采用薄层内位移线性变化条件下的动力Green函数形成桩-土-桩相互作用所需的土介质柔度矩阵,用梁单元模拟桩的运动,用振型分解方法建立上部结构等效刚度矩阵,利用上部结构底部位移和力的关系与承台运动方程共同求解来考虑上部结构与桩基承台间的动力相互作用,以任意地震波入射为初始运动输入,建立了层状土介质中群桩及其上部结构体系对入射地震波响应的半解析分析模型,研究了桩基及其上部结构体系对不同角度入射SH、SV和P波的动力响应。结果表明,本文提供的方法不仅具有较高精度,而且计算工作量较小。

In this paper,a semi -analytical method to calculate the response of pile group embedded in a layered soil - superstructure interaction system to arbitrary incident seismic waves is presented. The plane - strain assumption used for dynamic analysis of pile foundations is abandoned and Kausel's dynamic Green functions which was developed by assuming the displacements within each layer to vary linearly is used to form the soil flexibility matrix. The pile is modelled by beam elements. The modal superposition method is used to form the equivalent stiffness matrix of superstructure. The interaction between superstructure and footing is considered through the relationship between displacement and force at the base of the superstructure which is solved together with the equilibrium equation of footing . The arbitrary incident seismic wave is applied as the primitive input of pile foundations . The results of a numerical study on the behavior of pile foundation - superstructure interaction system subjected to SH and P waves with different angles of incidence are presented . It is shown that the method developed in this paper has the advantage of high accuracy and less computational time.