Dynamic Risk Assessment Of Subway Deep Foundation Pit Construction Based On Monitoring Data

With the continuous development of China’s economy and urban construction,the above-ground space has gradually become crowded.In order to efficiently use urban space,the number and scale of high-rise,super-high-rise buildings and urban subways are increasing,and the safety risk of deep foundation pit construction is also increasing.Therefore,the risk management of the deep foundation pit project has always been the focus of experts and scholars.Undoubtedly,construction information monitoring is an important barrier to ensure the safety of deep foundation pit projects.How to reasonably use on-site monitoring information for deep foundation pit construction risk assessment is a research direction worthy of attention.This paper takes the deep foundation pit project of a station of Dalian Metro Line 5 as the engineering application background,and systematically studies the risk assessment method of subway deep foundation pit construction based on monitoring data.The main work and conclusions of the paper are as follows:(1)Based on the existing literature,the characteristics of the deep foundation pit project are summarized and analyzed;from the perspective of risk management,the definition of risk,risk elements and characteristics,risk management process and other deep foundation pit risk management theories are explained,and the deep foundation of the subway is briefly introduced Construction monitoring of the pit;an inductive analysis of the construction accidents of the deep foundation pit from both the type and cause of the accident,emphasizing the rationality and importance of judging the risk status of the actual situation of the deep foundation pit at different stages of construction and proposing The idea of risk assessment of deep foundation pit construction based on monitoring data.(2)Based on the inductive analysis of the foundation pit monitoring project,the risk assessment indicators are selected according to the principle of index selection,and a deep foundation pit construction risk evaluation system based on monitoring data is established;first,the COWA algorithm is used to weight each indicator;to monitor the project Based on the early warning value and alarm value of the security risk characteristics,the security of the monitoring items is graded.The D-S evidence fusion theory is used to analyze and synthesize the actual monitoring data to determine the security level of each monitoring item.Probability,and then use the expert survey method to estimate the loss of risk accidents,calculate the risk level of each evaluation index based on the credibility method;finally combine the weight calculation to obtain the overall risk state of the foundation pit,and complete the subway based on the monitoring data.Construction of dynamic risk assessment model of foundation pit.(3)Analyze Analyze the engineering risk characteristics of a deep foundation pit at a station on Dalian Metro Line 5,determine the assessment indicators based on the actual monitoring situation and the principle of indicator selection,and make a dynamic risk assessment of the single monitoring project of the foundation pit and the overall construction of the deep foundation pit and draw the risk The change curve intuitively reflects the safety status of deep foundation pits at various stages.Through analysis and research,it proposes reasonable response measures for high-risk monitoring projects,which verifies the rationality and practicability of the risk assessment method in this paper.Provide a useful reference for the risk control of foundation pit construction.