| With the increasing number of domestic subway construction projects,shield method,as the most widely used construction method in underpass tunnel construction,has huge investment,complex construction and many safety hazards.Once a safety accident occurs in shield construction,it will lead to significant casualties and property losses as well as a relatively bad social impact.Therefore,it is very necessary to study its safety risk management and control.First of all,based on the study of the literature related to safety risk management of metro construction at home and abroad,this paper elaborates on the concept of shield construction of metro tunnels in the context of shield construction.It mainly introduces its characteristics and construction process flow as well as risk definition,composition and characteristics,risk management and other related basic theories.To avoid the occurrence of safety accidents,this paper analyzes the safety risk factors of subway tunnel shield construction from five aspects: analysis of safety risk occurrence mechanism,statistics of shield construction-related accidents,analysis of fishbone diagram of typical accidents,literature survey research,and questionnaire survey,and establishes a construction safety risk evaluation index system consisting of six primary indicators and 27 secondary indicators.Then,based on the evaluation index system,in terms of risk evaluation,the index weights are determined by the combination of assignment method based on game theory,in which the hierarchical analysis method determines the subjective weights and the entropy weight method determines the objective weights.Based on the theory related to the cloud model,the risk classification of the safety risks existing during the construction of the shield structure of the subway tunnel is divided into 5 levels,so as to build a construction safety risk evaluation model combining the combined assignment method and the cloud model.Finally,the index system and safety risk evaluation model constructed in this thesis are applied to a certain interval tunnel shield construction project of Zhengzhou Metro Line 8,and the comprehensive weights of relevant indexes and cloud characteristic parameters are calculated by expert scoring method.The risk cloud and standard cloud synthesis cloud map are generated by the cloud generator,thus showing the risk status of each level of evaluation index,and thus judging the safety risk level of the whole project.The study shows that the risk cloud expectation value Ex of the project is2.593<4,and the construction safety risk level is low risk,among which the most influential one is personnel risk,and its weight is 0.229.The evaluation results are analyzed,and safety risk control measures are proposed from six aspects: environment,personnel,material,equipment,technology and management,and combined with the background of the 720 extra heavy rainstorm in Zhengzhou in 2021,a The flood prevention response mechanism and safety production management system of the project in the rainy season provide some reference values for safety risk management and control in the process of shield construction of underpass tunnel. |
