Surrounding rock deformation of high geostress soft rock tunnel under stabilization of supporting structure

摘要

The high geostress soft rock tunnel has been widely concerned by researchers because of its large deformation and high construction difficulty. This study analyzed the deformation of surrounding rock and the stability of support. Taking a tunnel in Western China as an example, firstly, the general situation of the project was introduced, then two different support schemes were put forward, and field measurement and FLAC 3D numerical analysis were used. The experimental results demonstrated that the contact pressure between the surrounding rock and the initial support presented a variation rule of rapid growth, slow growth and tendency to be stable. Moreover, the vault pressure was small, the pressure on both sides was large, the pressure on the right side was larger than that on the left side, which has a characteristic of lateral extrusion. The deformation of surrounding rock is fast first and then slow. The final deformation of surrounding rock of Scheme A was about 45 mm, and that of scheme B was about 55 mm. The final deformation of the secondary lining of Scheme A was about 28 mm, while that of Scheme B was about 25 mm, which was 10.71 % smaller than Scheme A. The extrusion deformation of the tunnel face was relatively small. Overall, Scheme B performs better in stabilizing tunnels. This study shows that the support structure which is added with metal support can provide a stable support force, which is conducive to the long-term stability of the tunnel and has a guidance role for the construction of tunnels.