Abstract:Characteristics of tunneling engineering tend to be long,big,deep-buried and difficult. Seepage in tunnels threatens large-scale underground excavation,and gives rise to engineering troubles such as landslide,roof caving,water bursting,etc. The characteristic of groundwater occurrence is discrete and seepage is anisotropic. Relying on the longest highway tunnel in Gansu Province,Qidaoliang Tunnel,based on the achievements from non-continuum seepage in rock mass,seepage fields in the area with the maximum flow rate inflow into the tunnel is simulated numerically. Properties of the groundwater seepage in the tunnel and changes of the surface waters level are simulated under all kinds of conditions. Comparison between the simulated results and the measured ones shows that the theoretical analysis is correct and the calculating results are reliable.