Evaluating portal collapsing risk of Bailongshan mountain tunnel with grey clustering method

In this study, the portal collapsing risk of highway tunnels is simulated as a grey system. Six influential factors are selected as clustering object, criteria for each factor are analyzed and preset for clustering parameter calculation. For case study, the portal collapsing risks of the Bailongshan mountain tunnel is evaluated by the proposed grey clustering method. The tunnel, which is located in the segment from Bijie city to Duge town (all in Guizhou province, China) of Hangzhou-Ruili expressway, is a rock tunnel of 4170m with a detached oblate-mouth cross-section. The results from the grey-clustering analysis are compared with the judgment of tunnel engineers, and have shown good agreement with each other. This indicates that the proposed grey clustering method in risk evaluation of tunnel portals is reasonable, it is useful to predict the single-hazard risk of in the preliminary design stage of highway tunnels.