Expansion-Constriction Force Characteristics of Continuously Rails on Bridge under Fracture Condition of CRTS Ⅱ Track Slab Welded

In order to study the longitudinal stress and deformation characteristics and their influences on track and bridge structure under the fracture condition of CRTSⅡ track slab, a spatial coupling model based on the finite element method and bridge-slab-rail interaction mechanism was established. This model can analyze the influences of crack location, width and depth of track slabs, as well as the expansion-constriction stiffness of track slab and bed plate, on distribution rules of the expansion-constriction force of continuously welded rail (CWR) on bridge. Results show that, in order to calculate the expansion-constriction force of CWR on bridge under the fracture condition of CRTSⅡ track slab, a most unfavorable fracture location at track slab should be selected according to the different checking parts. Meanwhile, the crack width and depth of track slab are suggested to be 2 mm and 200 mm, respectively, and the expansion-constriction stiffness of track slab and bed plate should be reduced to 10%−50%, since in this way the calculation result is conservative without losing generality. Track slab fracture increases the fracture risk of cement asphalt mortar screed and bed plate; the longitudinal displacement of rail and the relative displacement between rail and track slab on the side of broken slab are changed dramatically at the crack.