Abstract:

Shrinkage and temperature-gradient action in self-compacting concrete can cause damage and deformation in ballastless track structures, resulting in irreversible degradation of the interfacial bonding performance between the track slab and the self-compacting concrete layer. In view of this, this study takes CRTS III ballastless track as the research object. Using the finite element method, a refined model that considers structural reinforcement and interlayer bonding is developed. The deformation behavior of the track structure and the damage evolution mechanism of the interlayer interface under thermal loading are systematically investigated. Combined with the multi-body system dynamics method, the vehicle-track coupling dynamics model is then established, and the influence of periodic track irregularity induced by temperature gradient action on the dynamic response of vehicle-track system is analyzed. The results show that shrinkage of the self-compacting concrete is effectively restrained by the door-shaped steel bars, which suppress the progression of internal interface damage. The interface damage between the track slab and the self-compacting concrete layer is mainly governed by positive temperature-gradient loading. When the gradient is +60 °C/m, the damage begins at the slab corner and gradually expands to the slab. Under a temperature gradient of +70 °C/m, localized failure occurs. In addition, temperature-gradient action induces periodic irregularities in the ballastless track unit, thereby intensifying wheel–rail dynamic interaction. The wheel–rail vertical force and track-slab vibration acceleration increase with increasing temperature gradient and vehicle speed.

Key words: high speed railway, ballastless track, deformation and damage, temperature gradient, cohesion model, wheel-rail relationship