Damage mechanism of slab track under the coupling effects of train load and water

The damage mechanism of slab track under the coupling effect of train load and water was studied in this research. Based on the law of mass conservation and momentum theorem, the hydrodynamic pressure expression was derived by using the control volume method. The effects of load characters, water viscosity, and crack shape were analyzed in this paper. In order to describe the stress field singularity of crack tip, the quarter-points elements at the crack tip were established, and the maximum tensile-stress criterion and mixed fracture criterion were used to analyze the coupled hydro-mechanical fracture of slab track. Through the presented analysis, it was determined that, the effect of water viscosity on hydrodynamic pressure is negligible when crack aperture is greater than 2 mm, and the value of hydrodynamic pressure depends linearly on axle load and is proportional to the square of train speed. The train speed is an important factor to affecting the crack propagation, and the crack propagation rate increases with the increasing train speed. It is concluded from the research that the mixed-model fracture criterion is more appropriate to analyze the coupled hydro-mechanical fracture of slab track than the maximum tensile-stress criterion.