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

Abstract

The 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 tunnel face, creating a conduit for water and inrush disasters easily occur. Accurately predicting the safety distance between tunnel face and fault fracture zone allows for effectively avoiding water and mud inrush disasters during construction. First, the analytical model of safety distance of water and mud inrush prevention is proposed, in which the rock zone between tunnel face and 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 published in the literature. 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 height of groundwater table, and decrease in 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.