Collapse Risk Assessment Of Deep Foundation Pit Construction In Subway Station Based On PSR-ANP-FCE Model

In recent years,with the expansion of the depth and scope of excavation of the foundation pit of metro stations,the difficulty factor of its foundation pit engineering has also increased,and safety accidents occur frequently during the construction process,among which collapse accidents account for the highest percentage,seriously hindering the smooth progress of metro projects.The causes of collapse accidents are not only objective factors such as the large volume of deep foundation pit projects and the complexity of the construction environment,but also partly due to the unsatisfactory evaluation and control of the risk of collapse of deep foundation pits in metro stations.In this regard,it is an urgent and meaningful task to find a new evaluation method to improve the effectiveness of the evaluation of the collapse risk of deep foundation pit construction in metro stations,in order to reduce the occurrence of collapse accidents.Firstly,this thesis uses the PSR(Pressure-State-Response)model to identify risk factors in terms of personnel,materials and site by applying the causation theory and case study analysis to the three basic questions of "what collapse occurred,why did the collapse occur and what should be done when the accident occurred".The risk factors identified were screened by expert scoring,and 32 key risk factors were identified to construct a collapse risk evaluation index system for deep foundation pit construction of metro stations;secondly,the network hierarchy analysis method was used to assign weights to each risk index,and the fluctuation test was conducted on the index weights through system dynamics to construct a fuzzy comprehensive evaluation model to evaluate the collapse risk of deep foundation pit construction of metro stations;finally,the risk evaluation model was used to evaluate the risk of a metro station project in Wuhan.Finally,the risk evaluation model was used to evaluate the risk of an underground station project in Wuhan,and the results showed that the collapse risk evaluation score of the station project was 57.824,and its risk level was medium risk,and the monitoring of the foundation pit should be strengthened to reduce the risk level and adopt targeted risk control measures.This thesis aims to improve the accuracy of the collapse risk evaluation of the deep foundation pit construction of the metro station,reduce the possibility of risky accidents and promote the smooth progress of the deep foundation pit project of the metro station.