Abstract: The effect of cracks on the stability of surrounding rock of the straight wall arched tunnel was simulated by using different types of finite element analysis software (RFPA2D and ABAQUS). Cracks were normally distributed in the arch bottom, sidewall, arch shoulder, roof and other parts of the tunnel. This study investigated the mechanisms of crack initiation and propagation and the damage-failure patterns of surrounding rock under the confining pressure. The detailed comparisons and discussions of these two finite element methods (FEM) were presented. The model tests using cement mortar were conducted to validate the results obtained by numerical simulations. There was a good agreement between experimental results and numerical simulations. The results showed that cracks at the corner were the weak position of surrounding rock in the tunnel. When the crack at the arc of the tunnel roof formed 45°angle with the arc centre of the tunnel roof, the compressive strength of the tunnel was the lowest and the stability was the worst. Under the confining pressure, tensile failure mainly occurred at the arch bottom and the roof, and shear failure was observed at the sidewall and the crack tip.

Key words: crack, numerical simulation, rock failure process analysis, tunnel