中文摘要：

基于层状横观各向同性饱和土地基模式,研究了桩基在饱和土体中的纵向耦合振动问题。首先,根据饱和介质三维波动理论的Biot模型,利用Hankel变换,给出横观各向同性饱和土波动方程的轴对称通解;利用通解,建立了饱和土层的精确动力刚度矩阵,进而构建出盘面和竖向柱面荷载作用下,土体与结构动力相互作用的Green函数;其次,根据桩-土界面的位移协调及平衡条件,用边界单元法构建了层状饱和地基与桩相互作用的动力方程和计算公式,给出求解层状横观各向同性饱和地基与桩基纵向耦合振动的一般解法。算例表明：土介质的各向异性参数、饱和土孔隙率和桩-土模量比,对低频振动桩的动力刚度影响不大,但对高频振动影响显著。

英文摘要：

This paper presents a study of the coupled vertical vibration of piles in layered transverse-isotropic saturated soils.Based on Biot＇s theory for fluid-saturated porous media,the symmetrical general solutions of wave equations for transverse-isotropic saturated soils are obtained by using the Hankel transform.Using the general solutions,the exact dynamic stiffness matrices for a layered saturated stratum and a saturated half-space are derived,and the dynamic Green＇s functions are obtained for internal barrel distributed vertical loads and disk loads,respectively.A system of algebraic equations by satisfying interface equilibrium and compatibility between the pile and the layered transverse-isotropic saturated soils are introduced using the boundary element method.The calculation results indicate that the effects of such parameters as the anisotropic elastic parameters for the soil skeleton,the porosity of saturated soils,and the elastic modulus ratio of pile and soils,on the dynamic impedance of the pile are relatively weak when subjected to low-frequency vibration,while on the other hand,the effects are significant when subjected to high-frequency vibration.