Two-Dimensional Numerical Model for Stability Analysis of Tunnel Face Based on Particle Flow Code

In this paper, numerical simulations of face stability shallow tunnels are carried out by using the particle discrete element codes PFC2D from microscopic view. Progressive instability tunnel is achieved through withdrawal baffle used to simulate face. Under different retreating displacement face, evolution laws support pressure on ground deformation, surface settlement and contact force chain in front studied. The results show that with can be divided into four stages, namely, rapid decline stage, minimum slow rising horizontal stage. Moreover, based simulation chain, discriminated methods failure zones proposed. research obtained paper will provide theoretical for reasonable value a practical engineering.