Effect of daily changing temperature on the curling behavior and interface stress of slab track in construction stage

Interface damage, which even happens in construction phase, has become a major problem for China Railway Track System (CRTS-II) slab track. The slab track in construction stage is a block structure and sensitive to daily changing temperature. In order to reveal the temperature behavior of the slab track and provide meaningful information to the control of early interface damage, a three-dimensional finite element model of slab track was developed to study the deformation and interface stress of the slab track under daily changing temperature in this paper. The daily changing temperature was measured on a testing platform constructed in open field, and imported to the model using user-defined subroutines UTEMP. Based on the developed model, the effect of initial temperature and construction seasons were then investigated. The analysis indicates that the slab deformation and stress change with time obviously and the positions of maximum interface stresses are near the slab corner, which is consistent with the location of interface disease. Initial temperature has significant influence on the slab temperature behavior. The initial temperature at 14:00 induces the largest interface tensile stress exceeding the interface bonding strength, while the interface stresses are relatively small from 19:00 to 24:00. Therefore, it is suggested that CA mortar injection should be finished before midnight. Additionally, as the overall temperature variation and temperature gradient are very obvious in summer, spring and autumn, the grouting operation of CA mortar in these three seasons is required to pay equal attention.