Analysis of early-age mechanics and crack of the base plate on the bridge in summer based on eXtended FEM

Abstract

Based on the eXtended Finite Element Method (XFEM), taking the base plate of the double-block ballastless track on the new high-speed railway bridge in the southeastern coastal area as the research object, the finite element model of the base plate was established to investigate the early-age mechanical properties and cracks under the high-temperature environment in summer. The on-site tests of temperature monitoring and crack observation were carried out on the base plate at an early age to validate the correctness of the model. The influence of the groove radius, anti-cracking rebar mesh, and curing methods on the mechanical properties of the base plate was further analyzed. As the age increases, the principal tensile stress in the groove exceeds the standard value of the concrete tensile strength, and the crack appears at the groove first. Increasing the radius of the chamfer can effectively reduce the maximum principal tensile stress in the groove, where the reduction rate is 15.80% and 31.11% respectively when the radii are 200 mm and 300 mm compared with the radius of 100 mm. The horizontal and vertical anti-cracking rebars in the groove have a significant reduction effect on the maximum principal tensile stress in the groove, of which horizontal laying is the most effective. A reasonable selection of curing methods is conducive to reducing the early-age cracking risk in the grooves, with plastic film covering curing being one of the more favorable methods. This paper provides a certain reference value for studying the early-age mechanical behavior of the base plate on the bridge and the influencing factors of the cracks at the groove.