Risk assessment of shield tunnel collapse accident based on fuzzy analytic hierarchy process

The collapse of shield tunnel seriously endangers the safety of urban subway construction and causes adverse social impact. In order to quantitatively evaluate the collapse risk of shield tunnel and ensure the normal construction of shield tunnel, the risk assessment model of shield tunnel collapse is established based on fuzzy theory and analytic hierarchy process. Taking the collapse risk assessment of the tunnel from Dahongmen South Station to Heyi Station of Beijing Metro Line 8 as an example, 4 first level indicators and 12 second level indicators are selected to define a fuzzy evaluation system. The weight set of evaluation factors is derived according to the hierarchy. According to the average membership degree of each index, the risk degree is calculated by fuzzy operator and the evaluation vector is obtained by applying the principle of multifactor fuzzy relation synthesis. The comparative analysis shows that the on-site monitoring results are very consistent with the lowrisk value obtained from the fuzzy evaluation, which proves that grouting reinforcement is the most effective method to prevent tunnel collapse. The engineering practice has verified the scientificity and rationality of this method, which gives full play to the advantages from qualitative to quantitative, and has high accuracy and universal applicability.