On The Treatment Of Tunnel Water Inrush In The Fault Fracture Zone Of Strong-weathering Migmatitic Granite

The construction of highway and railway tunnel usually traverses the fault fracture zone, which teems with inrush disaster. Inrush disaster has long been recognized as one of the most difficulties for tunnel project since it not only threatens the safety of tunnel construction, but also induces a multitude of negative effects of the surrounding environment. Given this situation, the research on water inrush in the fault fracture zone is of great significance.This paper investigates the project characteristic of the fault fracture zone, its extent and wall rock in the case of Cengxi Tunnel project. The thesis is conducted by combining spot-surveying, which adopts high-density resistivity method,CSAMT, geological forecast detecting instruments and other geophysical prospecting methods, and sampling analysis of geological drilling. On this basis, the research analyzes the cause mechanism of tunnel water inrush and proposes relevant treatment measures in terms of simulation analysis of COMSOL. The outcome and conclusion of this paper are as follows:1. On the basis of geophysical prospecting method and drilling exploration method, this paper asserts that the fault fracture zone distributes in upward parabola, lest the project requires to highlight controlling and diverting water. The sampling of drilling demonstrates that the wall rock of the fault fracture zone is destabilized and water-expanding in the project.2. On the basis of the investigation, this paper maintains that Cenxi Tunnel water inrush is labeled as water diversion fault inrush. Through the mechanical model of tunnel water inrush, this paper also finds that Cenxi Tunnel is characterized by fault activation water inrush.3. This paper deliberates the treatment of Cenxi Tunnel water inrush by expounding the measures such as emergency water pumping and surface subsidence treatment, which effectively harnesses water inrush. Furthermore, full-face curtain grouting and partial pre-enforcement with small ahead-grouting pipe are conducted to prevent water inrush from recurring in this tunnel project. In addition, some technical parameters are also provided in this paper.4. This paper adopts MIDAS/GTS to analyze the tunnel with grouting reinforcement. Through simulation analysis on the transfusion-stress coupling of three excavation methods, this paper finds that the water inflow has reduced extensively. Furthermore, the method of ring-excavation with the core soil reserved is found to have the minimum stress in the preliminary bracing. Ultimately, the field measurement verifies the simulation results.This paper concludes that the research method and results of the water inrush in the fault fracture zone in the Cenxi Tunnel project can be applied to similar projects.