Discrete Element Modelling of Rubber-Protected Ballast Performance Subjected to Direct Shear Test and Cyclic Loading

Yunlong Guo,Yameng Ji,Guoqing Jing,Qiang Zhou,Valeri Markine

doi:10.3390/su12072836

Yunlong Guo, Yameng Ji + Show 3 more

Open Access

https://doi.org/10.3390/su12072836

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Abstract

The rubber-protected ballast (RPB) is made from natural ballast particles and crumb rubber particles. The crumb rubber is shredded waste tires. RPB was chosen to replace the ballast as it has higher resistance to breakage and abrasion. However, the static and dynamic performance of the RPB has not been confirmed yet. Towards this end, experimental tests and numerical simulations were utilized to study the feasibility of RPB application. Direct shear tests (DSTs) were performed and a DST model and three-sleeper track model with the discrete element method (DEM) were built. The shear strength, settlement, displacement, and acceleration of the RPB were studied. The results show that the RPB has the advantage of increasing the force (stress) distribution and that the smaller crumb rubber size was more suitable for replacing the ballast particles.

Highlights

Railways provide the biggest universal network for rapid, economic, and safe passenger and freight transportation [1]
The test rig parameters and the ballast parameters were confirmed by comparing the Direct shear tests (DSTs) simulation results with the experimental results, which are explained in detail
The direct shear test model is validated by the experimental tests, afterwards, the parameters are confirmed and applied in the three-sleeper track model

Summary

Introduction

Railways provide the biggest universal network for rapid, economic, and safe passenger and freight transportation [1]. The ballast layer is one of the most essential components in a ballasted track, and it is built by placing ballast particles underneath and between the sleepers as the load-transmitting platform and for conveniently restoring track geometry [3,4]. For the better performance of these functions, the ballast is carefully selected, considering such qualities as material, strength, and erosion resistance, after undergoing cyclic loadings, ballast particles become severely deteriorated (e.g., breakage and abrasion) [7,8]. This deterioration is exacerbated by increasing axle load (freight line) and train speed (passenger transport) [9]. Frequent maintenance is performed to restore the track geometry, and ballast replacement is needed as soon as the ballast layer fails [14]

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