Influence of Type of Sleeper–Ballast Interface on the Shear Behaviour of Railway Ballast: An Experimental and Numerical Study

Abstract

The shear resistance at the sleeper–ballast interface of a ballasted track is an important contributor in maintaining track stability under faster and heavier axle loads where the ballast undergoes significant lateral sliding. Different types of sleeper–ballast interfaces based on the type of sleeper arrangements, such as concrete sleepers, timber sleepers, and under sleeper pads (USPs) attached to the concrete sleepers influence the lateral stability of railway tracks. Therefore, in this study the shear and degradation behaviour of ballast at concrete–ballast, timber–ballast, and USP–ballast interfaces were examined in the laboratory using large-scale direct shear tests under 60 kPa normal stress. The use of waste materials in the construction of civil infrastructure is gaining a lot of interest in the engineering community. Therefore, in addition to commercial USPs manufactured using raw materials, recycled USPs manufactured from granulates of end-of-life rubber tyres were also tested in this study. The discrete element modelling (DEM) approach was used to predict the shear behaviour of ballast at 30, 90, 120, 150, and 180 kPa normal stresses. The bonded particle model (BPM) was adopted in the DEM to simulate the effects of particle breakage during shearing. The results exhibited that both commercial and recycled USPs significantly improve the shear resistance at the sleeper–ballast interface while reducing particle degradation compared to concrete and timber sleeper interfaces.

Wheel-rail impact load due to the loss of sleeper-ballast interface

“…Lammering and Plenge [6] considered suspended sleepers as a long-term cause of track fatigue. Navaratnarajah et al [7] examined shear behavior at the sleeper-ballast interface, studying the influence of under-sleeper pads (USPs) made of recycled tires on ballast shear behavior. USPs create a softer surface, increasing sleeper-ballast contact area and reducing ballast pressure [8,9].…”

Evaluating Different Track Sub-Ballast Solutions Considering Traffic Loads and Sustainability

“…As outlined in [2], it serves to protect the subgrade from traffic loads and prevent mud from pumping into the ballast layer by providing separation and drainage for rainwater or groundwater. Numerous studies by researchers [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] have explored sustainable solutions related to geotechnical layers in railway tracks, such as ballast and sub-ballast, with their objectives including (i) enhancing the load-bearing capacity of the railway track, (ii) reducing strains from traffic loads, (iii) repurposing waste materials, (iv) proposing alternative materials, and (v) minimising ballast breakage.…”