Analysis Of Safety Risk Factors Of Subway Diaphragm Wall Construction Based On Fault Tree Analysis

Subway construction is becoming increasingly common in current urbanization construction,and as a common support structure method,underground continuous walls are widely used in related subway construction.Its construction technology has gradually matured after long-term development,but the actual construction process is complex and uncertain.If there are serious consequences of safety accidents,accident prevention still needs to be strengthened.In order to effectively prevent the adverse effects of safety accidents on the construction party,construction personnel,and society,it is necessary to have a comprehensive and systematic understanding of risk factors in order to effectively formulate preventive measures.In order to comprehensively analyze the risk factors of subway underground continuous wall construction,this paper collects and organizes 32 accident cases,5 major construction process studies and expert interviews.The preliminarily identified risk factors are classified from six aspects: personnel,equipment,machines,methods,environment and management,and a fault tree model is constructed and qualitatively analyzed.Combined with the fault tree bottom event design questionnaire,106 effective subway underground continuous wall construction safety accidents and causes were collected to relevant practitioners,and the causes of accident cases were synthesized,and the data were sorted out for quantitative analysis of the fault tree.Then,by converting the fault tree model into a Bayesian network,the collected data is reused to infer the main risk path.Since the fault tree analysis part of this paper only starts from the perspective of risk probability,in order to ensure that the research perspective is comprehensive,the "risk level" index is introduced through the risk degree theory.Firstly,according to the degree of loss caused by the accident caused by the bottom event,the analytic hierarchy method is used to obtain the weight.Then,the results are synthesized with the relative probability importance in the quantitative analysis of the fault tree,and the risk level of the bottom event effectively reflects the two dimensions of risk probability and loss degree,and the key risk factors are refined and suggestions are given.In this paper,33 risk factors are analyzed through fault tree,39 minimum cut sets are obtained from the qualitative analysis of fault tree structure,and 10 main risk paths are screened out by Bayesian network.The quantitative analysis further ranked the bottom events from probability importance and relative probability importance through objective data,and concluded that the bottom events under the two subtrees of method and environment had a greater impact on the probability of occurrence of top events.The results of risk level analysis based on risk degree theory show that the unfavorable geological and hydrological environment,steel cage manufacturing defects,support structure construction substandard and other bottom events are more important in terms of probability and loss degree.Finally,combined with the analysis results,this paper gives suggestions for construction safety risk prevention from three perspectives: people,materials and technology.