Prediction of Tunnel Water Inrush Volume in Granite Alteration Zone

Large-scale water inrush occurred in the horizontal lead of the No. 2 inclined shaft of the Hongdoushan tunnel, which mainly passes through non-soluble rock formations such as mica granite and metamorphic granite mylonite. In order to predict the water inrush volume of the tunnel in the granite alteration zone, the engineering characteristics of the granite alteration zone in the Hongdoushan tunnel and the cause mechanism of the water inrush are analyzed. A relevant hierarchical structure model of water inrush evaluation was established. Combining the hydrogeological conditions, geological conditions of the study area with the on-site monitoring, the hazard of the Hongdoushan tunnel’s water inrush is classified. Finally, fuzzy mathematics is used to predict the water inrush from the horizontal guide of the No. 2 inclined shaft of Hongdoushan tunnel. The results show that: (1) The influencing factors of water gushing in Hongdoushan tunnel are mainly divided into three aspects: engineering geology, hydrogeology and tunnel working conditions, with 9 factors in total. Based on these factors, the predicting model is thus established. (2) The predictions of water inflow given by the proposed model have a percentage error of 2.61 compared to the actual one, which could meet the requirement of engineering application. Thus, the proposed model could provide accurate predictions on relevant engineering.