Energy evolution characteristics of ballasted track with elastic layers

Elastic layers (ELs), including under sleeper pad (USP) and under ballast mat (UBM) have been used to enhance the elasticity and mechanical performance of ballasted track. Previous studies mostly focus on macro settlement and ballast crushing of ballasted track with ELs, with little consideration of energy evolution characteristics. Investigating the energy evolution is crucial for understanding the role of ELs in energy consumption, absorption, and transformation, thereby optimizing their design and improving performance. Here, the discrete element method (DEM) simulation models of ballasted track without and with ELs under cyclic loading were established to study the influences of USP and UBM on energy evolution characteristics of track structure from a mesoscopic perspective. The results showed that the ELs reduce friction dissipation energy and damping dissipation energy inside ballasts, which helps to slow down the particle breakage and wear. Compared with damping energy dissipation, friction energy dissipation is the main form of energy dissipation of ballasted track. In the stable loading stage, elastic strain energy is the main energy form. The employment of ELs increases the proportion of elastic strain energy due to enhanced track elasticity. The stiffness of ELs significantly affects viscous strain energy and elastic strain energy in ballasted track structures.