考虑土体径向位移时桩土耦合纵向振动特性及其应用

从三维轴对称土体模型出发,同时考虑土体竖向和径向位移,对完整端承桩在垂直谐和激振力作用下与土的耦合纵向振动特性进行了分析。假定桩为竖直弹性等截面体,土为线性粘弹性体,其材料阻尼为滞回阻尼。首先通过引入势函数对土体位移进行分解,从而将土体动力平衡方程解耦,求解得到了土体的振动模态形式,然后利用该解,以小应变条件下桩土接触面上力平衡和位移连续条件来考虑桩土耦合作用,求解桩的动力平衡方程,得到了桩的频域响应解析解、桩顶复刚度和速度导纳。利用所得解对土体动力反应特性和桩的纵向振动特性进行了无量纲参数分析,得到了许多新的结论。

Pile-soil interaction in the pile longitudinal vibration considering radial displacement of soil with applications

Modelling soil as a three-dimensional axisymmetric continuum and taking its radial and vertical displacement into account, the interaction between a soil layer and an integral end bearing pile undergoing vertical harmonic load is theoretically investigated. The pile is assumed to be vertical, elastic and of uniform cross-section, and the soil is considered as a linear visco-elastic layer with hysteretic type damping. With the aid of two potentials, the displacement is decomposed and then the dynamic equilibrium equation of soil layer is uncoupled. Thus the soil layer alone is solved first and the vibration modes of the soil layer obtained are used to analysis the pile response and yield an analytical solution for the pile response in frequency domain, which is used to define complex stiffness and mobility at the level of the pile tip. A parametric study of the effect of these dimensionless governing parameters is conducted to illustrate the behavior of soil-pile interaction. Some new conclusions are drawn.