中文摘要：

给出了稳态振动时,垂直受荷群桩在横观各向同性饱和层状土中动力阻抗计算的一般方法。首先,基于Biot饱和介质的三维波动理论,借助Hankel变换,得到横观各向同性饱和土轴对称动力问题的通解,利用通解,给出饱和土层在Hankel变换域内的精确动力刚度矩阵,进而构建出饱和土层在竖向柱面荷载作用下的动力Green函数;其次,根据桩-土界面的位移协调及平衡条件,利用Kynia的方法,建立了饱和地基-群桩纵向耦合振动的边界元-有限元方程,给出了垂直受荷群桩动力阻抗的计算公式。算例表明：场地土的各向异性及土层刚度的变化,对摩擦型群桩动力刚度的影响要远大于对端承型群桩的影响。

英文摘要：

A method to calculate the dynamic impedance of pile groups subjected to vertical harmonic load in layered transversely isotropic saturated soils is proposed.Based on the Biot＇s wave theory for fluid-saturated porous media,the general solutions of axial symmetrical dynamic equations for transversely isotropic saturated soils are presented by means of the Hankel integral transform.Then,using the general solutions,the exact dynamic stiffness matrix in the Hankel＇s transform domain for a layered saturated stratum and saturated half-space is derived respectively,and the dynamic Green＇s function of saturated stratum subjected to internal barrel distributed vertical load is obtained as a result.Furthermore,through a combination of the boundary element method and the finite element method,a system of algebraic equations by satisfying the interface equilibrium and compatibility with pile groups and layered transversely isotropic saturated soils are introduced according to the Kynia＇s methodology.The calculated results indicate that the effects of the anisotropy in soil skeleton and the dynamic stiffness in layered saturated stratum on the dynamic impedance of end-bearing pile groups are relatively weak,but are obvious on that of friction pile groups.