Reliability Evaluation of a Shield Tunnel Waterproofing System in the Life Cycle Stage Based on a Combination Weighting Method and Cloud Model

To solve the fuzziness and randomness existing in the reliability evaluation of the waterproof reliability of the tunnel in the life cycle stage, the reliability evaluation grade standard and a new reliability evaluation model of shield tunnel waterproofing system based on a combination weighting method and cloud model are proposed. After comprehensive consideration of the characteristics of the shield tunnel waterproofing system, an evaluation index system of shield tunnel waterproofing reliability in the life cycle stage is established that consists of five primary indexes and 20 secondary indexes. The subjective and objective weights of evaluation indexes are calculated by using the improved analytic hierarchy process (AHP) and the improved criteria importance through intercriteria correlation method (CRITIC) method, respectively. The combination weights are calculated by game theory, ensuring the rationality of the weights of evaluation indexes. Cloud model theory is introduced to solve the fuzzy and randomness in the reliability evaluation process of shield tunnel waterproofing systems in the life cycle stage, ensuring the accuracy of the evaluation results. To verify the applicability of the proposed approach, it was applied to the reliability evaluation of the shield tunnel waterproofing system in the Nanjing Yangtze River. The evaluation result is V, which belongs to high reliability. The evaluation results are consistent with the actual situation, so the accuracy and adaptability of the model are verified. Thus, the proposed approach can be feasibly used in applications and can guide other similar projects.