高速铁路桥梁群桩基础动力阻抗影响因素分析

基础动力阻抗的获取是研究高速铁路桥梁土-结构动力相互作用的关键。本文利用有限元软件ANSYS,对若干影响高速铁路桥梁群桩基础动力阻抗的因素进行了分析。首先,利用ANSYS建立了面向工程计算的桩基础动力阻抗求解模型,并通过将计算结果与薄层法方法进行对比证实了其适用性。其次,基于京津城际线路所在的地质条件和群桩基础的实际情况,分别研究了桩基布置型式、承台埋深、桩身几何特性(长细比)、场地土层分布等因素对高速铁路桥梁群桩基础动力刚度的影响规律,并与各因素对静力刚度的影响规律进行了对比。最后,依据以上研究结果,从动力刚度的角度出发,对既有高速铁路桥梁群桩基础的设计思路进行了若干补充。

Parametric Study of Dynamic Impedance for Pile Foundations of High-Speed Railway Bridges

The dynamic impedance of foundations is the basis for soil-structure interaction analysis of high-speed railway bridges. The finite element software ANSYS is used to obtain the dynamic impedance of pile foundations with various parameters, based on which the parametric study is done. A project-oriented model for calculating the dynamic stiffness with the finite element software ANSYS is established according to its definition. The feasibility of this model has been verified through comparing its calculation results with those obtained by thin layer method. Using this finite element model, the influences of the pile layout, the embedded depth of pile caps, the geometrical features of piles (mainly slenderness ratio) and the distribution of soil layers on the dynamic stiffness of pile foundation are studied and compared with the corresponding effects on the static stiffness. Based on the analytical results, from the aspect of dynamic stiffness, some suggestions are proposed for the pile foundation design of high-speed railway bridges.