Analysis of the Influencing Factors of Crystalline Blockages in Mountain Tunnel Drainage Systems Based on Decision Analysis Methods

Crystalline blockages in mountain tunnel drainage systems are becoming a common environmental problem. Considering the lack of research on the influence degree of the factors affecting crystalline blockages in mountain tunnel drainage systems, this paper classified and evaluated the importance of relevant factors through decision analysis methods. Our purpose is to provide a comprehensive understanding of the primary factors causing crystalline blockages in tunnels. The influence factors are selected and categorized through a literature review, and then the influence factors are screened twice by the expert scoring method and the gray-whitening weighted function clustering method to eliminate the less important influence factors. Finally, the influence factors are evaluated systematically according to the hierarchical analysis method. The results indicate that the factors affecting the crystalline blockage of the drainage system can be divided into five categories: hydrology, geology, shotcrete materials, drainage facilities, and the cave environment. Among these factors, shotcrete materials are the key factors affecting the problem of crystalline blockages. Specifically, the density of shotcrete and the content of calcium in cement have a significant impact on the crystalline blockages, which have the following comprehensive weights: 0.221 and 0.152, respectively. Since the shotcrete materials are human controllable factors, they can be taken as the key research objects to solve the problem of crystalline blockages.