基于离散元法的桥隧区段道砟垫铺设宽度研究

Laying Width Research of Ballast Pads in Bridge and Tunnel Sections Based on Discrete Element Method

有砟轨道在桥隧区段刚性下部基础条件下更容易发生劣化,通常采用铺设弹性道砟垫的方式来改善有砟轨道的受力状态。本文采用离散单元法建立高速铁路有砟道床仿真模型,分析了刚性基础条件下不同工况道床动刚度、道砟颗粒间接触力、道床底部道砟与基础之间接触力的差异。结果表明:道砟垫宽度超过轨枕长度后,再增加道砟垫的铺设宽度所带来的改善效果不明显;双块式铺设形式会造成轨枕中部应力集中,使得道砟接触力增大,轨枕受跨中负弯矩的不利影响。对于高速铁路桥隧区等刚性下部基础条件的有砟轨道结构,建议道砟垫铺设宽度取2 600 mm,与轨枕等宽,中心线与轨枕中心线重合。

Under the rigid foundation conditions of bridge and tunnel sections,ballasted tracks are more prone to deterioration.Therefore,elastic ballast pads are usually laid to improve the stress state of ballasted tracks.This article used the discrete element method to establish a simulation model of the ballasted track bed of high speed railways,and analyzed the differences in dynamic stiffness of the track bed,indirect contact force between ballast particles,and contact force between the bottom ballast of the track bed and the foundation under different working conditions under rigid foundation.The results show that after the width of the ballast pad exceeds the length of the rail sleeper,the incremental improvement effect brought by increasing the laying width of the ballast pad will gradually decrease.The double block laying form will cause stress concentration in the middle of the rail sleeper,resulting in increased contact force of the ballast and the adverse effect of rail sleeper caused by the negative bending moment at the mid span.For ballasted track structures with rigid lower foundation conditions such as high speed railway bridge and tunnel areas,it is recommended that ballast pads should be laid with a width of 2600 mm,which is equal to the width of the sleepers,and the centerline should coincide with the centerline of the sleepers.