列车脱轨撞击U型梁动力仿真模拟及损伤分析

Dynamic Simulation and Damage Investigation on the U-type Girder Subjected to Derailed Train Collision

研究目的:城市轨道交通U型梁在极端状况下会受到列车脱轨施加的侧向撞击作用,从而导致结构损伤破坏,威胁行车安全。本文采用显式动力有限元软件建立列车-U型梁碰撞模型,对碰撞全过程进行仿真分析,探讨两者之间的碰撞作用机理,并将计算结果与相关规范报告进行对比,最后分析U型梁的碰撞损伤模式。研究结论:(1)根据列车-U型梁接触状态可将碰撞过程分为脱轨后自由运动、初始碰撞接触和后继碰撞接触三个阶段;(2)各个工况中列车的纵、横向碰撞力峰值均小于UIC规范建议值,横向碰撞力基本满足ACI报告建议值,列车减速加速度均接近或超过9.8 m/s2,大于ACI规范中建议的列车减速加速度值0.5g;(3)碰撞过程中车体动能绝大部分以摩擦形式耗散,初始动能较大的列车在单位时间内摩擦耗能较多,但其亦需更长接触摩擦过程使其停止;(4)列车减速过程中加速度越大,对于结构的损伤也就越严重,U型梁的碰撞损伤主要表现为翼缘混凝土剥落,腹板产生塑性应变,但结构整体未发生破坏;(5)本研究成果可为新建U型梁结构的防撞设计以及既有结构的防护措施制定提供参考。

Research purposes:U-type girder is at risk of being collided laterally by the derailed train under extreme cases,which will cause the damage of structure and threaten the traffic safety.The explicit dynamic finite element(FE)software was employed to build the train-U-type girder collision model and the whole impact process was simulated.The collision mechanism was discussed and the analysis results were compared with related codes and report.The damage mode of U-type girder was also investigated lastly.Research conclusions:(1) The collision process can be divided into three stages according to the contact status of train-U-type girder,i.e.,free motion after derailment,initial collision and contact,and subsequent collision and contact.(2) The longitudinal and lateral peak impact forces under each case were smaller than the suggested value in UIC code.The lateral peak impact forces met the required value in ACI report generally.The deceleration rates were close to,or greater than 9.8 m/s2,which exceeded the proposed value of 0.5 g in ACI report.(3) The kinetic energy of train was mostly dissipated by vehicle-U-type girder friction.The higher initial energy train would dissipate more energy by friction in unit time,and it also took longer time to make itself stop completely.(4) More severe damage of structure happened if the train had a greater deceleration rate.The damage of U-type girder mainly presented as the concrete spalling of U-type girder flange and plastic strain accumulation in web,while the overall failure of the structure did not happen.(5) This research results can provide helpful references for the protective design of newly constructed structure and protective measures development of existing structure.