Research On Construction Risk Assessment And Control Technology Of Fault Fracture Zone In Crossing The Sea Of Qingdao Metro Line 1

With the rapid development of economy,the existing traffic can not meet the needs of economic development.More and more coastal cities begin to build subsea tunnels.Compared with land tunnels,the construction environment of subsea tunnels is complex,which leads to many risk factors,difficult construction and high investment risk.Therefore,it is necessary to carry out research on risk identification,evaluation and control of subsea tunnel construction.This paper takes the fault zone of the cross section of Qingdao Metro Line 1 as the research object.The fault tree analysis method,fuzzy analytic hierarchy process,numerical analysis method and on-site monitoring method are combined to carry out the risk assessment and control technology research of the subway section of the Metro Line 1.The main contents are as follows:(1)Based on the cumulative effect of risk,an accident tree with water inrush and mud inrush as the top event is constructed from four aspects:survey planning stage,design stage,construction stage and material conditions of water inrush and mud inrush.Through back analysis,the identification and preliminary evaluation of construction risk of subsea tunnel are completed,and the biggest risk factors of subsea tunnel construction are determined.(2)According to the risk factors identified by fault tree,combined with the special geological conditions of Metro Line 1 crossing four groups of 18 fault fractured zones,the construction risk assessment system of fault fractured zones is constructed,and the construction risk assessment criteria of fault fractured zones of Metro Line 1 are established.(3)The construction risk assessment model of fault fractured zone of Metro Line 1 is constructed by using the method of Fuzzy Hierarchical Comprehensive Evaluation.The application method of the evaluation model is introduced in detail.According to the established risk evaluation criteria and model,the overall risk and secondary risk factors of the construction of the fault fracture zone are evaluated,and the risk level of the construction risk of the fault fracture zone is moderate risk,which belongs to acceptable risk.(4)According to the results of risk assessment of fault fracture zone,research on construction control technology of fault fracture zone is carried out.From four aspects of strengthening advance geological prediction measures,auxiliary measures,support measures and other control measures,concrete control measures for construction of fault fractured zone are put forward.(5)The grouting reinforcement scheme of fault fractured zone of Metro Line 1 was studied,the grouting method,parameters and technology of fault fractured zone construction were determined,and the risk control measures in grouting process were put forward.A numerical model is established to verify the effectiveness of the grouting reinforcement scheme by selecting the actual geology of the tunnel passing through fault f3-3.(6)Research on the optimization of the section of the fault fracture zone of Metro Line 1.According to the design data and the actual geological conditions of f3-3 fault,three types of cross-section are designed to establish the numerical model.The seepage field,stress field,plastic zone,lining internal force and economic benefit are compared and analyzed.The optimum section form for construction of fault fracture zone is determined.The rationality of the section is verified by comparing the simulated monitoring value with the actual monitoring value.In this paper,the study on risk management of faulted fractured zone construction of Metro Line 1 can provide some reference for the construction of subsea tunnel engineering.