Supporting structure failure caused by the squeezing tunnel creep and its reinforcement measure

Tunnels deeply buried have high crustal stress and are prone to large deformation disasters when encountering soft rock. The large deformation phenomenon during the construction process of the Maoxian Tunnel on the Chengdu-Lanzhou Railway is particularly evident. This article focuses on the large deformation problem of the No.1 inclined shaft of the Maoxian Tunnel, and uses on-site monitoring methods to explore the reasons for tunnel structure failure, and analyzes the mechanical behavior of the tunnel structure. By using numerical simulation methods, the effectiveness of the second-layer support in resisting creep loads in tunnels was studied, and the influence of the construction time of the second-layer support on the mechanical properties of the tunnel was discussed. The results indicate that the first-layer support in the tunnel is a structural failure caused by asymmetric deformation caused by creep, while the second-layer support has a good effect on resisting creep loads. The research results can provide a technical reference for deformation control of squeezing tunnels.