Research On Safety Risk Management Of Underwater Tunnel Constructio

Shield method for construction are the distinctive features of fast speed,strong adaptability to environment,impact on the approaches to construct objects small and has high safety coefficient and so on,with these advantages make it become one of indispensable important role in urban subway tunnel,especially the slurry balance shield construction,gradually become when shield crossing the rivers and lakes of underwater shield tunnel construction operations such as the first choice.However,with the increase of shield diameter,the uncertainty of excavation stratum and the complexity of surrounding environment,the safety risk of large-diameter underwater shield construction is very high,and it is easy to occur the instability of excavation face,water leakage and other engineering accidents.Therefore,it is urgent to identify the safety risks that may be encountered during the construction of large-diameter underwater shield tunnel,and reduce the probability of accidents through corresponding measures.Based on this,this paper,based on the north Oujiang crossing tunnel of S2 line of Wenzhou Municipal Railway,carried out in-depth and systematic research on the safety risk analysis and control measures of large-diameter underwater shield tunnel construction by means of literature survey,theoretical analysis and engineering application.The main work and achievements are as follows:(1)In view of the uncertainty of fuzziness and randomness in risk analysis process,an assessment model reflecting the safety risk level of large-diameter underwater shield tunnel construction is proposed by using set pair analysis method and cloud model method.(2)244 construction technical risk accidents in the process of shield tunnel tunneling in China from 2003 to 2021 were collected,and the occurrence time,accident situation,accident type and direct causes of shield tunnel construction technical risk accidents were statistically obtained.The safety risk index of large diameter underwater shield tunnel is analyzed from six aspects of human risk,material risk,manual operation risk,natural environment risk,human and social environment risk and construction risk.(3)Combined with the construction of the north Oujiang river crossing tunnel of S2 line of Wenzhou Municipal Railway project general situation,hydrogeological conditions,adverse geology,tunnel construction methods and construction difficulties,determine the shield tunneling process of the tunnel risk sources.Combined with the risk assessment model,the safety risk grade of the large-diameter underwater shield tunnel construction is intermediate risk,and the risk grade of manual operation and natural environment is high risk.(4)Based on the comprehensive evaluation results of the safety risk of the construction of the north Oujiang river crossing tunnel of S2 line of Wenzhou Municipal Railway,specific risk control measures are put forward from three aspects: the abnormal risk of shield tunneling attitude,the instability risk of the underwater tunnel face and the water inrush risk of the shield tunnel.