Analysis on the Precursor Information of Water Inrush in Karst Tunnels: A True Triaxial Model Test Study

Water inrush in karst tunnels usually results in casualties, equipment damage, project delays and other serious consequences. An important measure to ensure the safety of tunnel construction is to provide accurate prediction of water inrush during tunnel excavation. To study the stability of the surrounding rock under effect of a water-bearing cave in front of the tunnel face, a true triaxial geomechanical model test was carried out based on the engineering background of the Xiema Tunnel in Chongqing Province. The response regularities of multivariate physical information of the surrounding rock during rock failure and water inrush were obtained by monitoring the displacement, stress and seepage pressure of different monitoring sections. The results show that some internal connections exist among the kinds of physical information. When the tunnel face was adjacent to the disaster source, the change of displacement and stress was in a decreasing trend, and the seepage pressure increased first and then decreased during the tunnel excavation. In addition, by fusion analysis, the sensitivity priority of precursor information for a rock failure and water inrush disaster in karst tunnels was summarized as stress, displacement and seepage pressure. Finally, the theoretical basis of the prediction of water inrush in karst tunnels had been established, which proved the feasibility of predicting disasters according to the precursor information.