Professional evaluating system for karst tunnel gushing based on AHP and its application

For the purpose of quantitative and semiquantitative description of impacting factors of the evaluating system for karst tunnel gushing, which will help us to predict the geological disasters directly and effectively, the paper has adopted Analytic Hierarchy Process (AHP) to quantitatively integrate multi-factors of tunnel gushing, with synthetic index (Skarst) for judging karst tunnel gushing being concluded, which will be used to evaluate the risk for tunnel gushing under different karst hydrogeological conditions. A case study of tunnel gushing by applying AHP has been operated in Wuchiba, and we have concluded the results as follows: the sections of ZK259+890～ZK258+500 and ZK255+405～ZK253+182 are the places with low risk for tunnel gushing, whose Skarst is lower than 0.24 (including 0.24); the sections of ZK256+300～ZK255+405 and ZK258+500～ZK257+500 are the places with middle-class risk for tunnel gushing, whose Skarst is in the range of 0.24～0.70(excluding 0.24, but including 0.70); the sections of ZK257+500～ZK256+300 is the place with high risk for tunnel gushing, whose Skarst is higher than 0.70 (excluding 0.70).