Dynamic impact of unsupported sleepers on railway infrastructure with a coupled MBD-DEM-FDM model

This paper introduced a numerical simulation model of vehicle-track-substructure system, which combines the multi-body dynamics method (MBD), the discrete element method (DEM) and the finite difference method (FDM). In this model, rail, fastener, sleeper and ballast particles were built based on the DEM by using Particle Flow Code (PFC) software, substructure (including subgrade and foundation) was built based on the FDM by using Fast Lagrangian Analysis of Continuum (FLAC) software, and the vehicle was built based on the MBD by self-programming. Here, two-way coupling calculation is implemented to satisfy the force equilibrium and displacement compatibility between railway components established by different method. And then, this coupled MBD-DEM-FDM model was validated by comparing the results with those from the classical vehicle-track dynamic model (VTCD model) and field test results. Afterward, the influence of unsupported sleepers on meso and macro dynamic behaviour of railway infrastructure was investigated. The coupled MBD-DEM-FDM model possesses the capability to accurately simulate the interaction between trains and tracks, analyze the meso mechanical responses of railway infrastructure, and capture significant subgrade deformations. Consequently, the proposed model offers a comprehensive understanding of the deterioration processes within railway infrastructure.