Risk Analysis of Water Inrush into Karst Tunnel Using Fuzzy Comprehensive Evaluation Method

In south western China, soluble rocks used to be karstifled intensively and water and mud inrush becomes one of the most dangerous geological disasters when tunnel is constructed. Identifying all potentially dangerous parts in the geological profile along tunnel route and making risk evaluation for them using geological exploration data may help prediction work significantly further in construction stage. Rock karstification usually controlled by a set of factors such as lithology, geomorphology, circulation of water and paleokarst, among them 7 main controlling factors are selected as risk rank indicators. The risk evaluation model based on fuzzy mathematics is put forward and potentially dangerous parts along tunnel are differentiated into 4 ranks according to risk index. The evaluation method is applied in the Qiyue mountain tunnel and the results show that it is a good method. The comprehensive advance geology prediction and prevention measures can be made according to ranks.