考虑挤土效应时楔形桩纵向振动阻抗研究

Vertical Dynamic Impedance of Tapered Piles Considering Compacting Effects

摘要:

基于复刚度传递多圈层平面应变模型,研究考虑桩周土挤土效应时成层地基中楔形桩的纵向振动问题。首先根据桩周土体的纵向成层情况并考虑楔形桩的变截面特性,将桩土系统沿纵向划分为有限个微元段,对每个微元段的桩周土体建立复刚度传递多圈层平面应变模型,并通过剪切复刚度递推方法求得桩周土作用在桩身的剪切复刚度;然后将求得的剪切复刚度代入桩身纵向振动控制方程,运用Laplace变换技术和阻抗函数递推方法,推导得到考虑桩周土挤土效应时成层地基中楔形桩纵向振动时桩顶复阻抗的解析解;最后,采用参数研究方法在低频范围内分析挤土效应对桩顶复阻抗的影响及其规律。

Abstract:

On the basis of the complex stiffness transfer model, the vertical vibration of tapered piles embedded in layered soil is theoretically investigated by considering the compacting effect of the soil layer surrounding the tapered pile in the piling process. First, the pile-soil system is discretized into finite segments, which allows for the stratification of the surrounding soil and variable cross-sections of the tapered piles. Since the complex stiffness transfer model has the ability to simulate the compacting effect, the complex stiffness of various soil segments in addition to those of the tapered piles is obtained. The analytical solution of the complex impedance of the tapered piles under longitudinal excitation force is then derived by substituting the complex stiffness into the vertical dynamic governing equation of the tapered pile and using the Laplace technique and impedance function transfer method. Finally, the influence of the compacting effect of the surrounding soil on complex impedance at the pile head is investigated within the low-frequency range using the parametric study method.