Dynamic mesoscopic response mechanism of rubberised epoxy asphalt trackbed subjected to high-speed train loading

Rubberized epoxy asphalt trackbeds, incorporating crumb rubber (CR) particles within the cured matrix, demonstrate superior vibration damping and deformation resistance characteristics. Current research remains predominantly focused on macroscopic properties, leaving a critical knowledge gap regarding the particulate-scale mechanisms controlling their dynamic performance under high-speed rail loading. This study bridges this gap through advanced discrete element modeling,developing two-dimensional DEM representations of four sleeper-asphalt composite units with varying CR concentrations (0%, 2%, 4%, and 6%). The models demonstrate exceptional validation accuracy against finite element analyses, with track stiffness predictions within 96.7−152.4 kN/mm range (maximum deviation <2.07%). Our particle-scale investigation of 350 km/h loading cycles reveals three key phenomena: (1) CR content proportionally increases dynamic deformation (stabilizing at 0.5 mm for 6% CR after three loading cycles), while simultaneously enhancing elastic recovery and cumulative deformation resistance; (2) CRparticles redistribute contact forces (0−100 N), with 4% content as a critical threshold shifting behavior from aggregate-dominated to CR-controlled; (3) This transition optimizes stress distribution and force chain homogeneity, achieving optimal balance between flexibility and stability. The findings provide essential insights for designing high-performance rubber-modified railway trackbeds.