Analysis of segmental cave-in Probability of Maojingba tunnel in Daqing-Guangzhou Expressway

Risks are widely existing in highway tunnel construction and are related to many influential factors. Based on the analysis of engineering conditions of Maojingba tunnel in Daqing-Guangzhou Expressway, a grey-clustering model is established to evaluate the segmental cave-in Probability level. In this study, six influencing factor, including surrounding rock gradation, tectonics, tunnel embedment depth, cross-section span, segment length, and the constructional methodology is considered. In order to rationally calibrate these parameters in different dimensions, a criterion set is studied and employed to classify the six influential factors into four severity grades. A group of triangular weight functions are devised to calculate the membership value of risk factors to probability grades. With the quantification process, natural engineering conditions are synthesized to work out the probability level of cave-in risk. The analyzed possibility of five segments is compared to an expert assessment and have shown good agreement. This indicates that the proposed probability analyzing model is suitable. The results can be used to evaluate the cave-in risk level for highway tunnels.