The Safety Risk Identification Of Xi'an Metro Deep Foundation Pit Engineering Construction Based On Fault Tree

Subway project construction is a complex project,deep foundation pit construction is an important part of subway construction,facing severe safety problems,such as the collapse of the construction of the foundation pit,gushing water and the serious deformation of the envelope.The safety of the accident will be eliminated in the early stages of its occurrence,and deep foundation pit construction caused by excessive ground subsidence is the main reason for many accidents and common causes,station deep foundation pit has been studied very mature,subway shaft deep foundation pit is a deep excavation for the tunnel and set up a deep foundation pit,because it is temporary foundation pit,and overlooked its safety,resulting in the surrounding building pipeline and the safety of the surrounding buildings.Therefore,the paper takes the settlement of the ground caused by the deep foundation pit construction of the shaft as the research object,and identifies the safety risk of the ground settlement caused by the construction of the deep foundation pit of the shaft.It is of great significance to prevent the occurrence of safety accidents in the foundation pit and improve the safety risk management of the subway And theoretical significance.To this end,the paper mainly from the following four aspects:1)Decompose the deep foundation pit construction of the shaft in virtue of work breakdown structure,and decompose the the safety risk caused by the construction with risk breakdown structure.Take ground settlement caused by the construction of the deep foundation pit of the shaft as the target,and couple the work breakdown structure matrix and the risk breakdown structure matrix and establish the four layer of matrix.Then safety risk factors of ground settlement during construction will be identified.2)Using the method of job decomposition and risk decomposition to construct the fault tree model from bottom to top,it has the characteristics of comprehensive analysis and simple operation,which is more suitable for risk identification and evaluation than its traditional top-down construction method.3)Based on the traditional Graham evaluation method and the safety risk assessment based on deep foundation pit engineering of tai xing section of Xi'an subway line 5,and the risk is assessment based on work decomposition and risk decomposition proposed in this paper Method,the conclusion of the two methods is basically the same,so the feasibility and validity of the method are verified.In this paper,the ground subsidence is the initial manifestation of many safety accidents.Combining with the construction of the deep foundation pit of the concrete subway,the paper puts forward the safety risk identification and evaluation of the ground subsidence caused by the deep foundation pit construction.Through the identification and evaluation of safety risk,it can improve the prejudging ability of risk factors in the process of deep foundation pit construction,and can avoid and resolve the safety risk before the construction safety accident,so as to improve the safety performance of the whole system.