Analysis and Calculation of Lining Water Pressure of High Water Pressure Karst Tunnel

Karst stratum is one of the most difficult geological conditions encountered in the process of tunnel construction. In addition to the risk of water and mud gushing during construction, there are also diseases such as leakage and cracking of lining structure caused by high water pressure. Based on the new Yuanliangshan tunnel project, this paper uses the analytical calculation method to study the influence of the change of tunnel seepage and water pressure on the water pressure behind the lining during the construction process, and draws a conclusion: increasing the thickness of the grouting ring and reducing the permeability coefficient of the grouting ring can reduce the seepage volume of the tunnel, and then reduce the water head behind the lining. The tunnel drainage and the water pressure behind the lining are linearly negative correlated. Based on the above study, it is suggested that the new Yuanliangshan tunnel adopt the grouting scheme of water blocking and drainage limiting to deal with the high water pressure in karst stratum. The thickness of grouting ring is 5m, which has the best water blocking effect and economic benefit, and can ensure the water pressure behind the lining is within its bearing range.