A Numerical Study of Railway Ballast Subjected to Direct Shearing Using the Discrete Element Method

Abstract

Railway ballast is a coarse granular material used to carry train loads and provide drainage for the rail tracks. This study presents numerical explorations of the mechanical performance of ballast aggregates subjected to direct shear tests. The discrete element method (DEM) was used to investigate the microscopic characteristics of ballast aggregates during shearing while considering contact distribution, particle rotation, and particle displacement. By testing the angle of repose of ballast aggregates, the parameters for the DEM contact model could be calibrated. Four specimens were prepared and then subjected to different normal pressures. The results show that the contact between ballast particles intensifies in terms of the amount and magnitude as the normal pressure increases. A Fourier analysis was applied to investigate the anisotropy of contact normal and the contact forces for ballast aggregates at different shearing phases. The rotational and translational movements of ballast particles were investigated, and this investigation revealed that particle rotation gradually increased as the shearing propagated. Four regions in the aggregates were identified according to the translational pattern of ballast particles. The results of this research provide an in-depth analysis of microscopic characteristics from a particulate scale.

Tutorial on the fragmentation of the railway ballast particles and calibration methods in discrete element modelling

“…Complex calibration procedures were performed to operate the simulations. [32] Related to discrete element simulations, a lot of laboratory or field tests have to be conducted [33][34][35][36][37], these articles deal with the ballast, ballasted tracks as well as track-vehicle interaction. These kind of models can be simulated in sophisticated computer programs.…”

“…Recent international literature [30][31][32] suggests that discrete element modelling will be indispensable for sophisticated modelling of granular sets in the future: both mechanically (micro as well as macro) and in terms of fragmentation.…”

Automated Shape Analysis and DEM Study on Graded Crushed Stone

“…e mechanical parameters of GCS like shear strength and deformation modulus can be affected by the packing characteristics. e shape index EI is set as the DEM [24] simulation variable to explore the influence of particle shape on packing properties, as shown in Figure 13(a). Considering the elongation variable, the GCS were selected and divided into 7 groups where EI is set from 0.4 to 1.0.…”