Research on Large Deformation Mechanism and Countermeasures of Shallow Buried Soft Rock Tunnel with Abundant Water

Abstract

In view of the obvious deformation characteristics of shallow buried soft surrounding rock tunnels affected by excavation disturbance, this article takes a Tunnel as the engineering background and combines the geological conditions of the tunnel to carry out on-site monitoring and analysis of surrounding rock deformation after tunnel excavation. The deformation after excavation has the characteristics of fast deformation speed, long duration and large deformation. In addition, the excavation position and step have an important influence on the settlement of the vault and the convergence of the surrounding rock. The settlement of the vault and the convergence of the surrounding rock caused by the excavation of the upper and middle steps account for 61.16% and 63.34% of the total deformation respectively. Through the analysis of large deformation and collapse phenomenon, it is known that the large deformation mechanism in the cave mainly includes soft rock plastic flow and progressive loosening expansion. The soft rock plastic flow caused phenomena such as side wall bulging, top pressure and steel arch distortion, and the progressive loosening and expansion caused the collapse of the tunnel face and surface cracks. Finally, according to the principles of the New Austrian Method, temporary support (transverse bracing + vertical bracing) + grouting anchor pipe + spray-mixing coordinated support was used to construct the pipe shed at the same time, and the support was optimized, the leading small conduit was encrypted, and added Measures such as temporary invert and lock-foot anchor pipe have successfully dealt with the large deformation section of the collapse, and the treatment effect is good, which can provide reference and reference for similar projects.