Mesoscale modelling of CRTS II slab tracks subjected to thermal action and vehicle loads

The damage and deformation of the cast-in-situ concrete joint between the precast concrete track slabs of the China Railway Track System (CRTS) II is crucial to the safe operation of high-speed railways. To investigate the damage and deformation evolution of the joint concrete under thermal action caused by the natural meteorological environment and vehicle loads, this paper develops a two-dimensional coupled thermal-mechanical numerical model of the concrete joint at mesoscale, which analyzes the influence of three factors; i.e., concrete strength, joint concrete aggregate maximum diameter and vehicle speed. First, the meteorology and heat transfer theory are introduced to the thermal simulations. Then, nonlinear characteristic of the joint concrete is modelled by the two-phase composite material based on the ‘random aggregate algorithm’ and strain-based elastic damage theory at mesoscale. Cohesive zone model (CZM) is utilized to simulate the interfaces between precast slabs. Finally, the reliability of the proposed model is confirmed by the validation study using field measurements. From the results of the numerical example, the maximum aggregate diameter of the joint concrete significantly affects the damage evolution of the joint concrete, and concrete strength has slight effects on the joint uplifting.