Shield Construction Safety Risk Assessment of Metro Tunnels Based on Cloud Model

To reduce the safety accidents during the shield construction of metro tunnel and improve the safety level of metro construction, a shield construction risk assessment model of metro tunnel was established based on cloud model. Firstly, the safety evaluation index system of metro tunnel shield construction was established from person, machine, environment and management dimensions. Then, the cloud model, which could effectively solve the random uncertainty and fuzzy uncertainty of index factors, was used to construct the evaluation method. Finally, the evaluation model was applied to the Chengdu Metro Line 11. The results show that the safety risk of shield construction in Chengdu Metro Line 11 is between the secondary risk and the third level risk. It is necessary to pay attention to the daily management, and pay more attention to the environmental risks.