金山铁路既有线提速路基动力响应分析

Dynamic Response Analysis on the Subgrade of the Existing Speed Increase Jinshan Railway

基于无限元人工边界和基床—路堤—场地子结构系统,建立上海金山铁路既有线有限元模型,根据实测路基响应特征构造基床顶面动荷载,模拟列车以现行速度通过路基产生的动荷载,分析列车在现行速度43km.h-1和目标速度160km.h-1范围内变化时,普通路基在动荷载作用下的动力响应规律。研究发现:如果既有线路基床不改造,列车速度从43km.h-1提高至160km.h-1时,基床顶面动应力峰值将增大17%左右;路基面动应力沿基面以下深度方向呈指数形态衰减;与现行速度条件下基床顶面以下6.2m的影响深度相比,提速后影响深度增加了1.2m。

Based on the infinite artificial boundary and the substructure system of the bed-embankment-field,a finite element model of the existing Jinshan railway subgrade in Shanghai was established.According to the measured response characteristics of subgrade,the function of moving load on the bedding surface was built to simulate the actual dynamic loads produced by trains with the current speed.The dynamic response of the ordinary subgrade was analyzed under the moving loads produced by trains from the current speed 43 km·h-1 to the target speed 160 km·h-1.It is found that,if the train speed is increased to 160 km·h-1 from 43 km·h-1 without reconstructing the existing subgrade,the peak value of the dynamic stress on the bedding surface will increase by about 17%.The vertical dynamic stress on the subgrade surface declines with the depth below in the form of exponential decay.Compared to 6.2 m below the bedding surface under the present speed,the influence depth has increased 1.2 m after speed increase.