Ballast Wear: Insight from the Discrete Element Simulation of Tracks and Micro-Deval Tests

Abstract

Throughout the life of a track, ballast grains wear as a result of both the trains passing over the track and the maintenance operations (tamping). The morphology of the grains is changed: they lose angularity and fine particles are produced, causing a gradual loss of track performance. Eventually ballast substitution becomes necessary. In order to predict the evolution of this degradation, a multi-scale study is proposed. A comparison between the discrete element method simulations of the micro-deval attrition test and of the passage of trains over a sleeper is performed in order to link the microscopic loading to the production of fine particles experimentally observed. The same numerical approach is also used with the simulations of the track to detect families of contacts in order to determine characteristic loading paths at the micro-scale. Loads and displacements of both systems are then compared in order to discuss the relevance of the micro-deval test. © Civil-Comp Press, 2016.