Effects of Differential Subgrade Settlement on Slab Track Deformation Based on a DEM-FDM Coupled Approach

Xuhao Cui,Bowen Du,Gaoran Guo,Rui Zhou,Hanlin Liu

doi:10.3390/app11041384

Xuhao Cui, Bowen Du + Show 3 more

Open Access

https://doi.org/10.3390/app11041384

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Abstract

Slab track structures become deformed under the effects of differential subgrade settlement. According to the properties of the China Railway Track System (CRTS) II slab track on a subgrade, a three-dimensional (3D) coupled model based on both the discrete element method (DEM) and finite difference method (FDM) was developed. The slab track and subgrade were simulated using the FDM and DEM, respectively. The coupled model was verified. The deformation of the slab track and contact forces of gravel grains in the surface layer of the subgrade were studied under differential subgrade settlement. The effects of settlement wavelength, settlement amplitude, and other types of settlements were also discussed. The results demonstrate that the settlement amplitude and settlement wavelength of the subgrade have significant effects on track deformation. The deformation amplitude of the slab track increases nonlinearly with an increasing settlement amplitude of the subgrade. Increases in the settlement wavelength and amplitude of the subgrade significantly increase the maximum value of the contact force of the gravel grains in the subgrade. The maximum contact force of gravel grains near the boundaries of the settlement section can reach two to three times that of the unsettled condition, which makes it easy to accelerate the plastic settlement of the subgrade.

Highlights

High-speed railways have developed rapidly and the China Railway Track System (CRTS) II slab track has been widely used [1,2,3]
This indicates that the gravel contact forces at the center of the settlement section are reduced, but the contact forces between the gravel grains near the boundaries of the settlement range are increased
discrete element method (DEM)-finite difference method (FDM) coupled simulations were realized by adopting interface elements for data interaction

Summary

Introduction

High-speed railways have developed rapidly and the China Railway Track System (CRTS) II slab track has been widely used [1,2,3]. Xiao et al [15] analyzed the effects of differential subgrade settlement on the stress and displacement of the CRTS III slab track based on the finite element method. Zhou et al [17] investigated the effects of vertical deformation of the continuous beam structure of the CRTS I slab track on rail deformation based on the principle of stationary potential energy It can be seen from the above that there are more studies on bridge pier settlement, but relatively few studies on subgrade settlement. Xiang et al [18] established a numerical model for a slab track based on the finite element method and studied the effects of differential subgrade settlement on the stress of the slab track. It is expected that the obtained results could provide helpful guidance for the maintenance and optimization of high-speed railways

DEM-FDM Coupled Mechanism

Description of Subgrade Settlement

Effects of Subgrade Settlement

Effects of Settlement Wavelength

Conclusions