Load-deformation Responses of Ballasted Rail Tracks: Laboratory and Discrete-Continuum Modelling
Additional Publication Information
The recent and rapid urbanization and frequent congestion of roads have led to more attention being focused on ballasted tracks for freight and commuter transport. The mechanisms of ballast degradation and deformation, the need for effective track confinement, understanding of interface behaviour, determining the dynamic bearing capacity of ballasted tracks require further insight to improve the existing design guidelines for future high speed commuter and heavier freight trains. The load-deformation behaviour of ballast under cyclic loads is measured in the laboratory using a novel large-scale Track Process Simulation Apparatus (TPSA). A novel coupling model based on discrete element method (DEM) and finite element method (FEM) is developed to predict the load-deformation responses of the ballast assembly considering the interaction of discrete ballast grains and continuum subgrade. In this coupled model, the discrete ballast grains are modelled by DEM and the subgrade domain is modelled as a continuum by FEM. The results indicate that significant settlements are observed during the initial load cycles, followed by gradually increased deformation, arriving at a steady value towards the end of tests. Contact force distributions, stress contours and corresponding broken bonds are captured.