Research On Safety Risk Assessment And Control Of Submarine Immersed Tube Tunnel Construction

In recent years,with the gradual rise of subsea tunnel construction,subsea tunnel construction projects are increasing,especially the subsea tunnel construction projects using the immersed tube method.During the construction of submarine immersed tube tunnels,there are complex and uncertain risk factors,resulting in high construction safety risks.To ensure the safe operation of submarine immersed tube tunnel construction projects,assessing construction safety risks is a key aspect.In order to obtain accurate and reasonable risk assessment results,so as to provide a scientific basis for reducing construction safety risks.With the goal of building a complete and reasonable risk assessment system,research is conducted on the risk identification,risk indicator system construction,and risk assessment content of submarine immersed tube tunnel construction,in order to obtain a system that can accurately apply to the safety risk assessment of submarine immersed tube tunnel construction.The main work and research results of this paper are as follows:(1)In order to obtain a comprehensive construction safety risk indicator system,more accurate identification of construction safety risk factors is required.According to the huge and complex characteristics of subsea immersed tunnel construction,WBS-RBS is proposed to identify more comprehensive risk factors,and Delphi method is used to eliminate redundant indicators.The WBS work structure decomposition method is used to decompose the construction process in stages,and the RBS risk decomposition method is used to decompose the risk factors into different factor units.The WBS-RBS coupling matrix is constructed,and multiple risk indicators are identified.Based on the SMART principle,a safety risk assessment index system for submarine immersed tunnel construction is established,including 3 levels,6 aspects,and 26 indicators.(2)In order to obtain accurate comprehensive safety risk assessment results for underwater immersed tunnel construction,the Analytic Hierarchy Process(AHP)is used to calculate the weights of the primary and secondary indicators.Considering the issue of higher-order judgment matrices not meeting the consistency test during the calculation process,an improved Analytic Hierarchy Process(AHP-GA)based on genetic algorithm is proposed to modify the judgment matrix,allowing the higher-order matrix to pass the consistency test while improving the accuracy of weight values,thereby improving the accuracy of evaluation results.(3)In order to solve the problem that the uncertainty and fuzziness of risks have not been considered in the construction safety risk assessment of submarine immersed tunnels,a cloud model is proposed to link these characteristics and conduct a qualitative and quantitative construction safety risk assessment.A clear and intuitive risk assessment cloud map can be obtained.(4)Taking the construction of immersed tube section of Dalian Bay subsea tunnel as an example,the risk assessment of immersed tube tunnel construction is carried out.The construction project is of medium risk level,and there are two high risk factors and four medium risk factors in the construction risk factors.Based on the goal of safe construction of subsea immersed tunnel,in order to reduce the construction risk,it is necessary to study the risk factors of medium and high risk levels in the risk assessment results,analyze the causes of risks and the consequences,and formulate specific risk management and control measures in combination with the construction safety risk control standards and construction risk management specifications.