地震-高铁荷载共同作用下分层地基震动规律

Vibration of layered ground under combined effect of seismic and high-speed train loads

摘要:

为研究地震期间高速列车运行引起的地基震动规律,基于等效荷载法推导了频域内地震荷载输入公式,采用等效线性化方法考虑地基土非线性特性,结合高铁荷载下地基振动2.5维有限元计算方法,建立了地震-高铁荷载共同作用下非线性分层地基2.5维有限元模型,计算分析了车速及地基软硬对两动荷载共同作用下分层地基震动影响。结果表明:地震-高铁荷载引起的轨道中心处地面震动位移随车速的增大而增大；车速相同时轨道中心处地面震动位移随地基土刚度的增大而减小。地震和高铁荷载共同作用时地基震动会产生低频放大效应,车速越高、地基越软时地基低频震动放大效应越明显；两动载共同作用引起的地基中高频震动主要受列车荷载影响。近轨道中心处,地面震动主要受地震和高铁荷载共同作用影响；距轨道中心较远处,地面震动主要受地震荷载影响,高铁荷载的影响较小。

Abstract:

In order to investigate the ground vibration induced by the operation of high-speed trains during earthquakes, a seismic load input formula in the frequency domain was derived based on the equivalent load method, and the equivalent linearization method was adopted to describe the nonlinear response of soil. On the basis of the two-and-a-half-dimensional finite element method (2.5D FEM) of ground vibration under high-speed train load, a 2.5D finite element model of nonlinear layered ground under combined seismic and high-speed train loads was established. The effects of vehicle speed and soil stiffness on the layered ground vibration under combined loads were analyzed. Results showed that the ground vibration displacement at the center of the track caused by seismic and high-speed train loads increased with the increase in vehicle speed, and it decreased with the increase in the stiffness of ground soil under the same vehicle speed. There was a low-frequency amplification effect for ground vibration under the joint effect of earthquake and high-speed train loads, which was more obvious for higher speed and softer ground. The medium- and high-frequency ground vibration induced by combined loads was mainly affected by the train load. The ground vibration near the center of the track was greatly affected by the combined action of seismic and high-speed train loads, while that far away from the center of the track was mainly affected by the seismic load and less affected by the high-speed train load.