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基于饱和多孔介质理论,研究了成层饱和黏弹性土层中端承桩的纵向振动特性。首先利用Novak薄层法,得到了土层对纵向振动桩的动力阻抗。其次,将桩等效为Rayleigh-Love杆,给出了成层饱和黏弹性土中端承桩纵向振动的一般分析方法和桩头动力复刚度的解析表达式。具体分析了两层饱和黏弹性土中端承桩的纵向振动特性,得到了桩头动刚度因子和等效阻尼随频率的响应特征,讨论了物理和几何等参数对动刚度因子和等效阻尼的影响。结果表明:桩长径比、土层模量比以及桩土模量比等对桩头动刚度因子和等效阻尼有显著的影响。相比于均质土层中的桩,上层土越硬或下层为软弱土层,桩的动刚度因子和等效阻尼振动幅值增大,其周期随长径比显著变化,且对于大直径桩,动刚度因子和等效阻尼随频率呈振动变化。同时,土体与孔隙水相互作用系数和桩泊松比等的影响相对较小。其结果可作为桩基动力基础设计和动力检测等基础数据。
Based on the theory of saturated porous media, the longitudinal vibration characteristics of end-supported piles in saturated viscoelastic soil layers are studied. Firstly, using Novak thin layer method, the dynamic impedance of soil to vertical vibrating pile is obtained. Secondly, the pile is equivalent to a Rayleigh-Love rod, and a general analytical method of longitudinal vibration of bearing pile in layered saturated viscoelastic soil and analytical expression of dynamic stiffness of pile head are given. The longitudinal vibration characteristics of the end bearing pile in two layers of saturated viscoelastic soil are analyzed in detail. The dynamic stiffness factor of the pile head and the response characteristic of equivalent damping with frequency are obtained. The effects of physical and geometric parameters on dynamic stiffness factor and equivalent damping Impact. The results show that the pile stiffness ratio and equivalent damping have significant effects on the pile head length-diameter ratio, soil-mass modulus ratio and pile-soil modulus ratio. Compared with the pile in a homogeneous soil layer, the upper soil is harder or the lower is a weak soil layer, the dynamic stiffness factor of the pile and the amplitude of the equivalent damping vibration increase, and the period of the pile changes significantly with the aspect ratio, and for the large diameter Pile, dynamic stiffness factor and equivalent damping change with frequency. At the same time, the influence of soil-pore water interaction coefficient and pile Poisson’s ratio is relatively small. The results can be used as the basis of pile foundation design and power detection and other basic data.