The paper deals with basic thought and method of prediction of water inflow into tunnel by fuzzy clustering theory, and presents main factors infuencing water inflow and their quantized formulae.

Based on the analytic formula of groundwater inflow into tunnel,this paper puts forward a method to choose the minimal rock cover of sub-sea tunnel.

To emphasize expatiating on how the method of grey systems analysis works in the estimation of water-gushing amount of the tunnel,then compare the result with two common methods.

Analysis and Curing Measure of Pi Shuang ao Tunnel Gushing;

The paper analyses the fundamental and method for the study work on discharge rate in karst tunnel gushing from the prediction of the discharge rate,and expatiates the method on the basis of special geologic condition in karst region.