Stability analysis of tunnel in sandy cobble strata under different pre-reinforcement techniques

Excavating tunnels in sandy cobble strata carries a high risk of ground collapse caused by instability the tunnel face. In order to prevent at face during excavation, this paper focuses on studying effects various pre-reinforcement method stability sand-cobble strata. Firstly, projects suitable for these are proposed. Then, using FLAC3D established numerical models, then simulate excavation process under six different working conditions: non-reinforced, with advance small pipes, pipe-roof, GFRP bolts, pipes and pipe-roof blots. The displacement stress fields soil behind front each condition obtained. results show that use bolts can effectively control deformation surrounding rock face, or reduce settlement crown. Pre-reinforcement combination better ensure process.