Research On Safety Risk Identification Of Metro Tunnel Shield Construction Based On SNA

The shield method is widely used in metro engineering tunnel construction due to its fast construction speed,small impact and few constraints.However,the shield construction process is faced with factors such as technical difficulty,harsh construction environment and complicated surrounding environment.A series of safety accidents such as ground collapse and tunnel leakage occurred.Therefore,it is urgent to use scientific and reasonable risk identification methods to determine key risk factors to reduce the occurrence of shield construction safety accidents.Traditional risk identification methods are apt to ignore the mutual influence of risks,making the result of risk identification insufficient,which is not conducive to formulating effective risk measures.From the perspective of risk correlation,this paper intends to construct a subway tunnel shield construction safety risk identification model in order to effectively identify the risk factors of shield construction safety risk and provide a theoretical basis for subway construction shield safety management.In order to scientifically and effectively identify the safety risks of subway tunnel shield construction,this paper relies on the practice of tunnel shield construction safety risk management of the Chengdu Metro Line 11 project,and comprehensively uses the decision-making test evaluation laboratory method and social network analysis method to develop a certain In-depth theoretical and case studies.First,according to China’s shield construction method specifications and related research literature,the concept of subway tunnel shield method,construction process and the characteristics of shield construction safety risks are introduced,and the correlation between risks is analyzed from the perspective of the mechanism of safety accidents.By collating the literature on risk identification in recent years,it is pointed out that the existing research methods cannot consider the relevance of risks,which leads to deviations in key risk identification results.The social network analysis method in the field of sociology can comprehensively consider the transmission effect of the correlation characteristics in the network structure,making the key risk identification results more scientific and objective,and it has not yet been applied to the research of shield construction safety risk identification,and combined with shield construction Methodological analysis of method construction safety risk characteristics.Then,a social network analysis method is used to construct a security risk identification model for subway tunnel shield construction.Use the accident statistics method to determine the list of shield construction safety risks,use expert scores to determine the direct impact matrix between the risks,use decision-making experiments and evaluation laboratories to convert the direct impact matrix into the overall impact matrix,and use threshold filtering to obtain the shield construction safety risk reachable Matrix to determine the interrelationships between final risks.The social network analysis method is used to transform the 0-1 risk impact relationship into a shield construction safety risk network structure.Based on the important "geographical location" of risk nodes in the network to determine the importance of risk in the network transmission process,the individual network is used.A ranking table of the intermediate centrality values and line centrality values of the network nodes is obtained through analysis,and the top 20% is selected as the key risk factor and key risk relationship according to the 28 rule.Finally,the model was applied to the Chengdu Metro Line 11 for an example analysis.The results showed that the construction personnel lacked safety awareness R2,ventilation or lighting equipment failure R6,tunnel support system instability R16,excessive ground settlement or collapse R27,and rainy season construction Insufficient preparation R31 is the key risk,and the underground operating environment is poor R30 → Construction workers lack of safety awareness R2 is the key risk relationship,and the analysis of the results is consistent with the actual situation.Based on the analysis of risk identification results,corresponding risk management measures are proposed,and combined with the overall network density value,it is demonstrated that controlling key risks can effectively reduce the risk transmission effect.This paper comprehensively uses modern security risk management theory and social network analysis methods to analyze the characteristics of security risks in shield construction,and builds a social network analysis method for the identification of security risks in the construction of subway tunnel shield methods.The case analysis shows that the model can effectively identify and control the key risk factors,and thus effectively reduce the transmission of safety risk factors in the construction of the subway shield method in the network.The related research results in this paper complete the theoretical research on the safety identification of subway tunnel shield construction in China,and the proposed risk management measures are beneficial to the shield construction of Chengdu Metro Line 11.