考虑河流冲刷作用的车桥耦合系统动力分析

Dynamic analysis of a vehicle-bridge coupled system considering river scouring

桥墩周围受到河流冲刷后,基础埋深减小,使得基础刚度降低,从而影响桥梁的服役状态。为研究河流冲刷对车桥响应的影响,计算了群桩承台基础的冲刷深度,并利用m法在承台底施加弹簧约束模拟群桩基础等效刚度,进而基于全过程迭代求解车桥耦合动力方程。作为算例,对比了某跨江特大桥桥墩冲刷前后的车桥动力响应与列车运行安全性。对比分析表明:铁路桥梁桥墩位于水流或潮水中时应采用考虑河流冲刷作用的有限元模型进行车桥动力仿真分析。受到河流冲刷之后,全部桥墩承台底面均高于冲刷线,各墩基础等效刚度在冲刷之后都减小,其中水平方向的平移刚度与竖向的抗扭刚度减小最显著;车辆动力响应普遍增大,车体横向加速度变化最显著,部分工况车辆轮重减载率超出规范容许限值,受冲刷之后简支梁跨中横向位移与横向加速度明显增大,影响行车安全。

Dynamic performance of a bridge is influenced by river scouring.In order to study the effect of river scouring on vehicle-bridge interacted vibration,the erosion depth of pile group foundation was calculated.Considering the variation of equivalent stiffness of foundation induced by river scouring,a vehicle-bridge coupled dynamic model based on a full process iteration was established.In a case study,the dynamic response of the vehicle-bridge system and the running safety of trains before and after river scouring were contrasted.The results showed that for a railway bridge located in a river or tidewater,the vehicle-bridge model considering river scouring is proposed to analyze the vehicle-bridge interacted vibration;after river scouring,all bottom surfaces of pile caps are above the river bed,and the equivalent stiffness of the foundation decreases significantly,the lateral responses of both simply supported bridges and vehicles increase obviously,the running safety of trains may be influenced.