Fire Risk Assessment Of Subway Operation Based On Fuzzy Fault Tree Analysis

Security has always been the key point of the field of traffic.In recent years,with the acceleration of urbanization,in order to solve the increasingly serious traffic problems,more and more cities have put forward the demand for urban rail transit.At the same time,urban rail traffic accidents frequently happen worldwide.Fire accidents account for a larger proportion of urban rail traffic accidents,which greatly affects operation safety and the social stability.The urban rail transit is a semi-closed and high-occupy system,and it gathers too many facilities and equipment to control all of the fire risk sources,which often cause serious consequences.Therefore,how to accurately identify and control risk sources of fire accident in urban rail transit system,and formulate an effective emergency plan to ensure the safety and stability of the subway operation,which has great realistic significance and broad application prospects.The main work of the paper is as follows:(1)The paper makes a comprehensive introduction to the related concepts of the theory of risk and the the risk theory and the accident causation theory,the process and technical method of risk assessment,and clarifies the evolution mechanism of the risk to the accident.Then it discusses the advantages,disadvantages and applicability of the common qualitative and quantitative risk assessment,and some preliminary suggestions are put forward for the fire risk assessment of subway operation.(2)The applicability of fault tree analysis(FTA)and that of fuzzy comprehensive analysis method in fire risk assessment of subway operation are introduced respectively.By qualitative analysis of the FTA,the minimum cut set,the minimum path set and the structure importance of the subway fire fault tree model are obtained.It shows that the fire accidents in subway operation are formed in many ways and the system with low safety index.Taking the risk of X subway station fire accident as an example,By establishing the risk index system of the subway operation fire,select the triangle fuzzy number as a membership function,the weight of the risk index and the fuzzy evaluation matrix are determined.According to the maximum membership degree principle,the fuzzy comprehensive evaluation of the subway fire risk is obtained.(3)Considering the operational mechanism and advantages&disadvantages of fuzzy comprehensive analysis and fault tree analysis,the qualitative and quantitative assessment method,fuzzy fault tree analysis is formed through blurring of the fault tree.At the same time,fuzzy importance analysis is improved to reduce the influence of the median method,and the concept and model of fuzzy risk degree are proposed to improve the risk assessment method of fuzzy fault tree.It not only makes up for the shortcomings of the fault tree analysis method,which cant get exact basic event probability,but also avoids the large error caused by the subjective factors in the fuzzy comprehensive analysis method.(4)Taking the risk of X subway station fire accident as an example,the fuzzy fault tree model is used to verify it.Through the minimum cut set and the minimum path set of the fire fault tree of the X subway station,the way to trigger and control the fire accident is determined.Through the quantitative and qualitative analysis process,the fuzzy probability of top event,the fuzzy importance and fuzzy risk degree of basic events are determined.Compared with the fault tree analysis method and fuzzy comprehensive analysis method,the applicability and superiority of fuzzy fault tree method in the fire risk assessment of subway operation is verified.It also provides reference for the subway station to prevent and control fire accidents.