公路下穿铁路新建泡沫轻质土过渡段框架涵动力特性分析

Dynamic Characteristics Analysis of Newly⁃built Foamed Lightweight Soil Transition Section with Frame Culvert in Highway Under⁃crossing Railway Line

针对武汉市李纸路以框架涵方式下穿南环铁路上行线及京南联络线工程,建立了车-轨-路涵过渡段三维有限元模型,分析了在运营车辆作用下泡沫轻质土过渡段-框架涵振动加速度、动位移及动应力分布规律。结果表明:由泡沫轻质土填筑而成的过渡段,其竖向加速度和动应力随着深度的增加而呈减小趋势,且在基床表层范围内衰减速度最快;列车上下桥两侧路基面动位移沿线路纵向分布规律及大小基本相同,往桥台方向呈现逐步递减的规律;泡沫轻质土过渡段中部范围动位移沿纵向递减速率小于过渡段末端;框架涵范围内桥涵顶面竖向动位移呈现出双峰分布规律。

In view of the project of Wuhan Lizhi Road under crossing the South Ring railway line and link railway of Beijing-Guangzhou railway and South Ring railway in frame culvert mode,a three-dimensional finite element model combined the vehicle,track and subgrade-culvert transition section was built. The vibration acceleration,dynamic displacement and dynamic stress distribution of foamed lightweight soil transition section and frame culvert under the action of operating vehicles were analyzed. The results show that the vertical acceleration and dynamic stress decrease with the increase of depth,and the attenuation rate is the fastest in the surface layer of the subgrade,when the transition section is filled by foamed lightweight soil. The longitudinal distribution characteristic and magnitude of the subgrade surface dynamic displacement under the train load on both sides of the bridge is basically the same,and gradually decreases towards the abutment. The longitudinal decreasing rate of the dynamic displacement in the middle part of the transition section of the foamed lightweight soil is less than that at the end of the transition section. Within the scope of frame bridge culvert,the vertical dynamic displacement of the top surface of bridges and culverts presents a doublepeaked distribution behavior.