地震和高铁共同作用下桩网复合地基振动特性

Vibration Characteristics of Pile-net Composite Foundation under Seismic and High-speed Train Combined Loads

为研究地震和高铁列车荷载共同作用下桩网复合地基振动特性,通过建立轨道-路堤-桩网复合地基三维有限元计算模型,分别与实测数据和一维波动理论对比验证模型的正确性。通过对比不同荷载工况下地面位移和加速度时频振动曲线,分析地震和高铁两动载共同作用时不同车速下桩网复合地基时频振动特性,研究桩体模量对桩网复合地基减震效果的影响。研究表明,Hollister地震荷载和高铁荷载共同作用下,距轨道中心1 m处地面振动位移由地震荷载主导,地面振动加速度由列车荷载主导;20 Hz以下地面低频振动由高铁和地震荷载共同控制,地面高频振动主要由列车荷载控制。Lytle Creek地震荷载和高铁荷载共同作用下,桩网复合地基地面振动位移和加速度峰值均大于高铁荷载单独作用下的值;增加桩体模量对高铁荷载单独作用和两动载共同作用下桩网复合地基地面振动均有减振效果,但两动载共同作用下增加桩体模量对地面减振效果比高铁荷载单独作用下弱。

To investigate the characteristics of ground vibration induced by seismic and high-speed train combined loads,a three-dimensional finite element model including track,subgrade and pile-net composite foundation were established.This model was verified by comparing its results with the measured results and theoretical solution.The acceleration and displacement of ground vibration under different train speeds were compared,and the effect of pile elastic modulus on ground vibration was analyzed.Results show that under the train and Hollister seismic combined load,the displacement of ground vibration at 1 m away from track center is dominated by seismic load,while the acceleration at the same position is dominated by train load.The low frequency ground vibration below 20 Hz is induced by the combined loads,while the high frequency vibration is dominated by train load.Comparing with the train load alone,both the peak value of displacement and acceleration of ground vibration in pile-net composite foundation are larger under the combined Lytle Creek seismic and train loads.Increasing pile modulus can reduce the ground vibration of pile-net composite foundation under both train load and the combined load,while the benefit of pile-reinforcement on vibration reduction under combined load is weaker.