Discrete element numerical simulation analysis of dynamic response of high-speed railway subgrade in goaf sites

REN Lianwei; WANG Ziqiang; ZOU Youfeng; DUN Zhilin; YANG Wenfu

doi:10.16186/j.cnki.1673-9787.2023020075

Abstract：Objectives High-speed railways running through goaf sites pose serious security risks.In order to study the dynamic response law of high-speed railway subgrade in goaf sites.Methods The numerical model of 17 groups of high-speed railway subgrade in goaf sites was established by 3DEC discrete element soft-ware.The distribution law of settlement deformation and dynamic stress in subgrade under different train loads was analyzed.The difference in dynamic response distribution between ballasted track and ballastless track subgrade was compared and analyzed.The influence of width and thickness of goaf on dynamic re-sponse distribution was analyzed.Results Compared with the ballastless track,the dynamic stress amplitude of the ballasted track subgrade is noticeably higher,but the attenuation rate of dynamic stress is also higher.The time-history curve of dynamic stress and dynamic displacement will increase gradually along the depth direction of the subgrade.With the increase of loading time,the amplitude of dynamic displacement in-creases gradually,but the increasing speed decreases continuously.And the dynamic stress amplitude re-mains basically unchanged.The linear relation exists between dynamic stress,dynamic displacement ampli-tude and axle load of train,which increases linearly with the increase of axle load.The greater the width and thickness of the goaf,the greater the amplitude of the dynamic displacement caused by the train load,but when the mining width is greater than a certain range,the amplitude of the dynamic displacement will de-crease.Conclusions The difference in train load,subgrade track type and goaf sites will affect the distribu-tion of dynamic response in the subgrade.The research results can be used as reference for the safe opera-tion of high-speed railways in goaf sites.