Study On Safety Risk Management Of TBM Construction Of Qingdao Metro Line 1

In the field of underground engineering,in recent years,TBM construction method is widely used in long tunnel construction because of its high efficiency and less harm to the environment.However,in the process of tunneling,TBM often meets the threat of bad geology.Once the type selection is determined,it is almost impossible to change the type.If the surrounding rock collapse,a large number of groundwater gushing,sand gushing and other risk events are encountered in the process of tunnel excavation,it will cause huge economic losses and construction delay.Therefore,TBM construction geological safety risk model to identify and predict the main risks is favorable to the risk management of construction companies.Based on the construction report of Qingdao Metro Line 1,this paper summarizes that there may be five types of geological risk events in Qingdao Metro Line 1,such as TBM jam shutdown,tunnel collapse,mud gushing and sand gushing from tunnel face,building cracking and inclination,and cutter head failure.Through case analysis,the breeding mechanism of these five types of risk events is studied.Based on this,the risk list is established,and the risk factors are screened by Delphi method.Finally,two top events of TBM jammer shutdown and building cracking and tilting are determined,seven intermediate events of cutter head,shield,cutter head failure,posture deviation,torque,tunnel collapse and face mud and sand inrush are determined,and the uniaxial compressive strength is improved There are seven geological risk factors,including rock integrity,large amount of groundwater,fracture zone,quartz content,clay and composite stratum in the stratum,five design risk factors,including cutterhead design,overbreak,horizontal curve radius,total thrust and building resistance,and four construction management risk factors,including grouting control,shoring pressure management and TBM operation in preliminary geological survey.According to the specifications,references and cloud model discretization method,the quantitative and qualitative grading standards are divided.Then,the structure and parameters of Bayesian network are determined by interpretive structure model and EM(expectation optimization)algorithm.With the help of SPSS software,the input indexes of Bayesian network are independent to avoid the distortion of the model results.Then,by using the Bayesian network reasoning software genie,it is judged that the five types of risk events of Qingdao Metro Line1 are in a low-risk state,and there are eight main causes:rock integrity~→tunnel collapse~→chuck cutter head~→TBM jamming,rock integrity~→tunnel collapse~→chuck shield~→TBM jamming,a large number of ground~→mud inrush and sand gushing in tunnel face~→buildings cracking and tilting,overbreak~→Torque~→chuck shield~→TBM jamming,horizontal curve radius~→attitude deviation~→TBM jamming,TBM operation~→attitude deviation~→TBM jamming,building resistance~→building cracking tilt,cutter head design~→chuck head cutter~→TBM jamming.Combined with causative chain,sensitivity factors and posteriori key factors,it can be inferred that rock integrity,large amount of groundwater,quartz content,cutter head design and shoring pressure management are the main factors causing TBM jamming,building resistance is the main factor causing building cracking and tilting,rock integrity and quartz content are the main factors causing cutter head failure,and rock integrity is the main factor causing TBM jamming The pressure management of support shoe is the main factor of tunnel collapse,and a large amount of groundwater is the main factor of mud and sand inrush.Finally,the model is applied to Haixiao and Wagui section of Qingdao Metro Line 1,and the assessment results are compared with the basic in construction site,which shows that the assessment tool is practicable and the results are steadfast,and the solutions are proposed for these five types of geological risk events.