考虑竖向荷载作用时液化土中高桩基础水平动阻抗分析

Horizontal dynamic impedance analysis of high pile foundation in liquefied soil considering vertical load

考虑竖向荷载与水平荷载的耦合作用,基于Biot饱和多孔介质理论,结合Novak薄层法,建立饱和土体中高桩基础的水平振动分析模型,引入势函数解耦,利用微分算子分解法和参数分离法,得到非液化饱和土中桩段的水平振动解析解。将上部液化土视作无黏性不可压缩流体,建立柱坐标下的流体运动方程,求解得到液化土中桩段的水平振动解析解。利用位移连续条件,通过矩阵传递法得到高桩桩顶的动力阻抗表达式,并退化与已有文献解进行对比验证,讨论液化土性质、竖向荷载等因素对桩顶动阻抗的影响。结果表明,高桩阻抗随液化土厚度的增加而减小;液化土厚度不变时,液化土密度在高频阶段对高桩阻抗影响更显著;竖向荷载的存在主要影响桩基动刚度,对桩基动阻尼几乎无影响。

Accounting for both vertical and horizontal loads,this work utilizes Biot’s saturated porous medium theory and the Novak thin layer method to develop an analytical model for horizontal vibration in high pile foundations within saturated soil.The concept of potential function decoupling is introduced,and the analytical solution for horizontal vibration within a pile section in saturated soil is derived using the methods of differential operator decomposition and parameter separation.The upper liquefied soil is treated as an inviscid,incompressible fluid,and an equation for fluid motion in cylindrical coordinates is formulated.The analytical solution for horizontal vibration within a pile section in liquefied soil is determined.By applying the continuity of displacement condition,the expression for the dynamic impedance at the top of a high pile is obtained using the matrix transfer method.The work examines the impacts of liquefied soil properties,vertical load,and other factors on the dynamic impedance of the pile top.Findings reveal a decrease in the impedance of high piles with increasing liquefied soil thickness.With a constant thickness of liquefied soil,liquefied soil density exerts a more pronounced influence on pile impedance in high-frequency stages.The presence of vertical load primarily impacts the dynamic stiffness of the pile foundation,with minimal impact on the dynamic damping of the pile foundation.