Abstract:

Water gushing with superhigh pressure occurs in the downslope construction of the exit section of Zhongtianshan tunnel on the second TurpanKorla railway in Xinjiang, China. Advance geology prediction and tests on the water inflow rate, water pressure and water conductivity are made to forecast the geological conditions ahead of the tunnel face and the variation pattern of the water inflow. Three options, i.e., advance grouting option, direct water releasing option and option of installing water releasing tunnel from the entrance section of Zhongtianshan tunnel, are proposed to cope with the superhigh pressure waterrich fracture zone. In the end, the advance grouting option is adopted and the waterrich fractured zone with 6.3 MPa water pressure has been successfully tunneled through. 

Key words: Zhongtianshan tunnel, downslope tunneling, superhigh water pressure, waterrich fracture zone, advance grouting