Numerical investigation and analysis of the evolution of ballast bed mechanical properties during dynamic stabilization

Abstract

Dynamic stabilization is a pivotal railway maintenance technique, which aims to enhance the bearing capacity and stability of ballast beds. Nevertheless, existing studies are limited by prohibitive computational costs and low fidelity model in numerical simulations, failing to holistically reveal the time-dependent evolution mechanisms on multi-scale mechanical properties during dynamic stabilization across the large-scale spatial domain. To address this gap, this study innovatively proposes an integrated MFBD and DEM simulation method that explicitly models the complete operation process of dynamic track stabilizer vehicle (DTSV) —from entry to exit the effective operational domain. Initially, a novel 3D dynamics model of the DTSV-ballasted track system was established using MFBD theory, while a ballast bed model incorporating six sleepers was developed via DEM theory. Subsequently, the dynamics model and ballast bed model were validated against field-measured acceleration responses and ballast bed properties during stabilization, respectively. Finally, the MFBD model simulated railway stabilization processes under complex scenarios, with rail-sleeper interaction loads transmitted as functional inputs to the DEM bed model, in an attempt to indirectly simulates dynamic excitations imposed by the vehicle-track coupled system on the ballast bed. The results elucidate, for the first time, the nonlinear evolutionary trajectories of inter-particle contact forces, coordination numbers, compactness and uniformity within distinct ballast bed zones during full-cycle stabilization operations. Furthermore, the time-dependent characteristics of macro-mechanical properties under varying operational parameters were investigated, establishing performance evolution functions for ballast beds. This research delivers practical guidelines for engineering practices, ultimately advancing theoretical research in railway maintenance.