| With the rapid development of social economy,the urbanization rate is higher and higher,and the traffic pressure is increasing.In view of the problem of excessive pressure of urban ground traffic,China has vigorously supported the development of subway construction in recent years.Shield construction has become the mainstream method of subway tunnel construction,and has been widely used.Shield construction is difficult,with high risk coefficient and high accident rate.There are many problems to be solved in risk management of shield construction.Therefore,it is necessary to adopt scientific,reasonable and effective methods to identify and evaluate the risks of metro shield construction stage,so as to provide scientific reference for the smooth progress of metro shield construction.The main research contents and results are as follows:(1)By summarizing the relevant data of subway shield construction at home and abroad since 2010,this paper identifies the risk factors in the process of subway shield construction,selects the main risk factors affecting subway shield construction,and constructs the corresponding risk evaluation index system.(2)Based on the fuzzy comprehensive Bayesian network method,the risk assessment of subway shield construction is studied.The Bayesian network method is used to calculate the probability of construction risk,and the fuzzy comprehensive evaluation method combined with analytic hierarchy process is used to calculate the loss degree of construction risk accident by using the software Yaahp.Through the calculation of risk probability and risk accident loss,the subway shield construction project is analyzed.Finally,a quantifiable result of the overall risk level is obtained.(3)The risk evaluation index system is applied to the construction risk evaluation of a shield construction section-D section in China.The causal relationship between the risk factors in Section D is analyzed and the Bayesian network model is established.The probability of risk occurrence in D section is 0.66 and risk level is 2 by Bayesian network method.On the basis of fuzzy comprehensive evaluation method,combined with analytic hierarchy process and software Yaahp,the risk accident loss score of Section D is 2.6414,and the risk level is 3.Through the assessment of risk occurrence probability and risk accident loss,the conclusion that the overall risk level of Section D is unacceptable is obtained,and the risk management plan and risk disposal measures are formulated.(4)Combined with the actual engineering situation of Section D,the overall risk level of Section D is grade 2,which is consistent with the actual construction situation.The results show that the research on the risk assessment of subway shield construction not only has important theoretical value,but also can be used to solve the practical safety problems of subway construction,and has broad application prospects in practical application. |
