Study on the damage evolution of the joint and the arching deformation of CRTS-Ⅱ ballastless slab track under complex temperature loading

摘要

Joint damage has been a severe problem for the longitudinal CRTS-II type ballastless track, which affects vertical stability of the slab track significantly and threatens operation safety of the highspeed railway potentially. This paper presents a refined and detailed finite element model of the CRTS-II track to investigate the damage initiation and evolution of the wide and narrow joint, a pivotal part of the longitudinal CRTS-II track. In detail, a bilinear cohesion model is introduced to simulate the interfacial interaction accurately. And a concrete damage plasticity model is utilized to model the initiation and propagation of the joint crack for comprehensive analysis. The refined model analyzes the joint damage initiation and evolution under complexly extreme temperature load. Then, the influence of joint damages and interface conditions on the slab track upper-arch mechanism are investigated. The results show that tensile damage causes initial cracks inside the narrow joint, then the increase of compressive damage is the leading cause of the final failure of the narrow joint concrete. And the poor quality of concrete tends to cause the wide and narrow joint to be entirely crushed, while the high quality above C30 may cause joint damage intensively, leading to joint concrete fall-block. In addition, the upper-arch on the track slab increases linearly with the joint damage degree. With the interfacial tangential shear strength changing from 0.01 MPa to 1.5 MPa, the maximum arch height of the slab reduces by 4.5 mm.