Study On Safety Sisk Sssessment Of Subway Shield Tunneling Construction

China's subway construction projects are in the number of surge and scale expansion,the shield technology has also been rapid development.As the subway shield tunnel engineering has the characteristics of huge scale,complex construction process,influence factors,large investment,the serious and influence consequences of a accident,Therefore,it is necessary to identify,estimate and evaluate the risk in the construction of subway shield tunneling,and provide reference for the successful completion of construction.In this paper,the subway shield tunnel construction safety risk assessments of each part have been studied in detail,mainly including the following aspects:(1)According to the extensive literature review,this paper summarizes the present situation and progress of subway risk management research,understands the current situation of risk management of subway shield tunnel,finds out the existing problems in risk research,and then puts forward the main research contents of this paper.(2)This paper introduces the basic theory knowledge related to risk management,and studies the risk mechanism,risk identification,risk estimation,risk assessment and risk response respectively according to the basic process of risk management;(3)According to the characteristics of the metro shield tunnel engineering construction,using the method of work breakdown structure(WBS)to break the work of the construction of metro shield tunnel into nine aspects as work shaft construction stage,preparation of shielddriven stage,shield-driven stage,normal shield tunneling stage,construction of connecting passage stage,preparation of shield arrival stage,shield arrival stage,through the special location stage and stop to overhaul and change cutter stage,and using the method of risk breakdown structure(RBS)implementing risk from the perspective of "4M1E" decomposition,and then build the WBS-RBS matrix on risk identification;(4)Combining the fuzzy set theory with the analytic hierarchy process,the fuzzy hierarchical risk analysis model is established,and the analytic hierarchy process based on triangular and trapezoidal fuzzy number arithmetic is studied.The fuzzy set theory is used to fuzzy calculate the risk probability and risk loss of the risk factors obtained by expert investigation,and to some extent to achieve the quantitative analysis of the risk estimates.Applying the improved analytic hierarchy process to obtain the weights of each level risk event relative to the upper level risk,and then derive the risk probability and risk loss of each level risk event;(5)The risk matrix method based on R =P ×C,Considering the impact of risk probability and risk loss of risk events on the level of risk,and then through the comparison with the corresponding risk indicators to determine the risk level of each risk event;(6)Based on the example of the tunneling project of Fuzhou subway line 2 # shaft to Fuzhou railway station,this paper uses the risk identification result and fuzzy level risk analysis model to carry out the construction safety risk assessment to verify the feasibility and practicality of the model.