提速对既有线路桥过渡段路基动力响应影响分析

Impact of speed raising on dynamic response of bridge-subgrade transition of existing railway

基于无限元人工边界建立了既有线有砟轨道路桥过渡段路基在动荷载作用下的三维有限元模型,模型考虑路桥过渡段倒梯形的结构形式,利用一系列移动轮载扩散到路基面的动面力模拟编组列车通过过渡段产生的动荷载,分析了既有线列车通行速度在现行速度80km/h和目标速度160km/h范围内变化时,路桥过渡段在动荷载作用下的路基动力响应规律。研究发现:列车速度从80km/h提升至160km/h后,路基面动应力峰值将增大20%左右;相比普通路基,路桥过渡段路基在提速条件下会产生较大的动应力;路基面动应力沿基面以下深度方向呈指数形态衰减。

Based on the infinite artificial boundaries,three-dimensional finite element model of existing railway subgrade of bridge-subgrade transition is established to study the response properties of the subgrade under moving load produced by trains of raising speed from 80 km/h to 160 km/h,considering the structure feature of inverse echelon.Moving load produced by trains passing through bridge-subgrade transition is simulated by a series of moving dynamic surface forces on subgrade surface due to wheel loads.It is pointed out that the peak value of dynamic stress on subgrade surface will increase by 20 percent when the train speed is upgraded to 160 km/h from 80 km/h,and vertical dynamic stress on the subgrade surface declines with depth in the form of exponential decay.Compared to the general subgrade,the brigde-subgrade transition produces greater dynamic stress on the conditions of the speedup of trains.