Stability analysis of the rock zone between the tunnel face and the fault fracture zone

Abstract Water and mud inrush is one of the main safety accidents that occur during tunnel construction in water-rich karst regions. Often, faulting occurs in front of the tunnel face, creating a conduit for water and inrush disasters can easily occur. Accurately predicting the safety distance between the tunnel face and the fault fracture zone allows for effectively avoiding water and mud inrush disasters during construction. First, an analytical model of the safety distance of water and mud inrush prevention is proposed, in which the rock zone between the tunnel face and the fault fracture zone is considered a thick rectangular plate with simple support on four sides. Subsequently, the proposed model is successfully verified through comparison with two existing models and engineering cases. Finally, the influence of main model parameters on the safety distance is further determined. This study shows that: (i) The safety distance increases with the increase in the cross-sectional height and width, and the burial depth of the tunnel; (ii) The safety distance increases with the increase in the effective gravity of the rock inside the fault fracture zone and the height of the groundwater table, and decreases in the dip angle of the fault; (iii) The safety distance increases with the increase in fault width, and the fault length has little influence on the safety distance.