基于Timoshenko模型的桩基多维动力阻抗分析

Multi-dimensional dynamic impedance analysis of pile foundation based on Timoshenko model

基于桩土相互作用的动力文克尔地基梁模型,桩基被等效为Timoshenko梁并建立运动方程。考虑桩身轴向压力的二阶效应及土层天然分层特性,提出计算层状土中单桩及群桩在水平振动阻抗的改进方法。通过数值计算,比较不同条件下Euler-Bernoulli模型与Timoshenko模型单桩及群桩桩顶振动特性。研究结果表明:采用Timoshenko模型计算所得到的单桩水平阻抗以及群桩相互作用因子均出现正值减小,负值增大的情况;且随着桩身长径比的变小,剪切刚度对该情况的影响也逐渐增大。同时桩顶轴向压力以及被动桩的空间相对位置对群桩相互作用因子的求取存在一定影响。

Based on the hypothesis of dynamic Winkler model between pile and soil,a vibration equation was established by making the pile equivalent to a Timoshenko beam.An improved method was deduced to compute the lateral dynamic impedance of piles,which took second-order effect of axial pressure and soillayer natural stratification characteristics into account.Through numerical calculation,the vibration characteristics of single pile and pile group under different conditions were compared between Euler-Bernoulli model and Timoshenko model.The results show that the horizontal impedance of single pile and the interaction factor calculated by Timoshenko model both decrease positively and increase negatively.With the decrease of the length-diameter ratio of the pile,the influence of shear stiffness on the situation increases gradually.At the same time,the axial load and the relative position of passive piles have some influence on the calculation of pile group interaction factors.