Abstract: Sandy dolomite stratum is widely distributed in the water conveyance tunnel of Yuxi segment of the Central Yunnan Water Diversion Project. Geological disasters such as collapse, water inrush and sand gushing often occur in the tunnels built in this stratum, which seriously affect construction safety. It is of great significance to scientifically and reasonably classify the level of dolomite sandification for disaster prevention and control in the construction process. In this paper, a hierarchical structure model consisting 12 indexes that accurately describe the degree of dolomite sandification is established by using the Fuzzy AHP method. The level of dolomite sandification is divided into slight sandification, weak sandification (lower section and upper section), strong sandification (lower section and upper section), as well as severe sandification. The upstream segment of Xiaopu 2# main tunnel is selected for model establishment and sandification level division. Results demonstrate that the method accomplishes the classification of dolomite sandification level by both qualitative and quantitative approaches, and the classification results are basically consistent with the current situation of the project.

Key words: dolomite sandification, sandification degree classification, Fuzzy AHP, sandification indices, Central Yunnan Water Diversion Project