考虑非一致地震输入的车-桥系统动力响应分析

针对地震对列车在高速铁路桥梁上走行安全性的影响,将桥梁在地震作用下的运动方程和车辆振动方程通过桥梁子系统与车辆子系统间的非线性轮轨接触关系联系起来,建立可考虑行波效应影响的长大跨度桥梁—列车耦合系统的地震反应分析模型。利用车—桥系统地震反应分析程序,对高速列车在不同特征地震荷载作用下通过某高速铁路连续梁桥进行仿真分析,研究列车速度和地震波行波效应对车—桥系统动力响应的影响。研究结果表明:地震波行波效应对车—桥系统的振动响应有重要影响,并不总是地震波行波速度越大,车辆的动力响应的计算结果越接近一致激励时的相应值;在进行大跨度连续梁桥车—桥系统的地震反应分析时,应按桥址处的实际场地土特性考虑地震波行波效应的影响;地震荷载作用时车体的横向振动加速度以及各项安全评价指标均随列车速度的提高而增大,在评价地震作用下高速铁路连续梁桥上列车的走行安全性时,必须考虑列车运行速度的影响,给出了确保地震发生时高速列车在桥上安全运行的临界速度限值。

Dynamic Response Analysis of Train-Bridge System under Non-Uniform Seismic Excitations

To study the seismic influence on the running safety of train passing high-speed railway bridges,a dynamic model of coupled bridge-train system subjected to earthquakes is established by connecting the motion equations of the bridge under earthquakes and those of the vehicles through the nonlinear contact relations between wheels and rails,in which the nonuniform characteristics of the seismic waves input from different foundations are considered.A computer simulation program is worked out.The case study is performed to a continuous bridge on the planned high-speed railway in China.The whole histories of the trains running over the bridge are simulated and the influences of train speeds and seismic wave traveling speeds on the dynamic response of the train-bridge system are studied.Results show that the effect of seismic traveling waves has great influence on the dynamic responses of the train-bridge coupled system,and it is not always true that the faster the seismic wave traveling speed is,the closer the dynamic response of the bridge-train coupled system to the corresponding ones under the uniform seismic excitations.The seismic traveling wave speed should be considered according to the property of the soil at the bridge site in calculating the dynamic response of train-bridge system subjected to earthquakes.The dynamic response of train vehicles including the lateral car body accelerations and the safety evaluation indexes all increase with the train speed,so the influences of train speed must be taken into account in evaluating the running safety of vehicles on the bridge during earthquakes.The critical running speed limits ensuring train running safely on the bridge during earthquakes are proposed.