A new DEM model to simulate the abrasion behavior of irregularly-shaped coarse granular aggregates

Railway ballast usually experiences continuous abrasion or breakage as subjected to repeated train loads. A novel 2D abrasion model is established based on the Discrete Element Method to capture the abrasion behavior of ballast with irregular shapes. A force-based failure criterion allowing for the Weibull distribution and size scaling law of strength is developed for abrasion recognition. In current model, ballast can abrade in either crushing or shearing mode, with each of them corresponds to a different fragment generation method after corner abrasion. A series of Los Angeles Abrasion (LAA) test simulations are conducted and the LAA loss is calibrated against the existing experimental data. The abrasion model and the calibrated strength parameters are further validated by the biaxial compression simulations. The evolutions of particle size and morphology during LAA test are also analyzed in terms of sphericity variation and ballast breakage index (BBI). The average sphericity and the BBI of ballast aggregates increase at a decreasing rate as abrasion aggravates. Using the calibrated model, the influence of particle morphology on the abrasion behavior of ballast is also investigated. It is found that particles with lower sphericities exhibit greater LAA loss and BBI value during LAA test. The proposed model provides an efficient and robust method to study the abrasion behavior of ballast aggregate involving with irregular shaped particles.