Application of a tracing experiment in the prediction of water and mud inrush in the Wantan Tunnel

Taking the Wantan Tunnel of Yilai Highway as the study case, the average water inflow and the water inflow in the wet season of the tunnel are calculated through field investigation, groundwater tracer experiment, groundwater flow monitoring, and atmospheric rainfall infiltration method. Meanwhile, the realistic failure process analysis(RFPA) is used to analyze the possibility of tunnel water inrush is judged. The results of field survey and tracer test show that the karst pipeline of Wantan Tunnel is a multi-branched, mixed-type karst pipeline with complicated hydrogeological conditions. The water inflow in wet season is about 4.6 times of the average tunnel water inflow. Mud failure will go through the stages of crack initiation, crack expansion, further crack expansion, and through-through failure. At the same time, when the water flow at the karst pipeline reaches about 2.7 to 3.5 times the initial value (37 248 m3/d), water gushing and mud inrush damage will occur, that is, when the flow of water outlet 2 reaches 10 000 to 13 000 m3/d, There is a very high risk of water and mud gushing in the Wantan Tunnel.