Study On Risk Assessment And Visual Early Warning Of Deep Foundation Pit Construction Of Metro

With the continuous development of urbanization,China’s subway construction has entered a golden development period.The deep foundation pit engineering of subway station is a comprehensive system engineering,which is difficult in construction technology and high in risk.Once a safety accident occurs,it will produce huge risk losses,seriously endangering the safety of people’s lives.Therefore,this paper takes the safety risk of deep foundation pit construction as the research object,from the perspective of risk pre control,through exploring the main safety accidents,identifying key risk factors,establishing the safety risk assessment index system,and realizing the dynamic assessment and visual warning of risks.The method strengthens the active control of risk and effectively prevents the occurrence of safety accidents.The main research contents are as follows:(1)Based on the shortcomings of traditional Bayesian network method,fuzzy theory,expert investigation,Leaky Noisy-OR are combined with Bayesian network to improve the reliability of Bayesian model network parameters.The key factors affecting the safety risk of deep foundation pit are determined by using Bayesian network,and the corresponding pre control measures are put forward.(2)Aiming at the selection of monitoring indicators,a quantitative calculation method based on key risk factors is proposed.By calculating the risk contribution rate of monitoring indicators,the optimization of monitoring indicators is realized,and the monitoring indicators are closely related to safety risk factors.(3)Based on the characteristics of "time and space effect" of the construction risk of deep foundation pit,the GA SVM risk assessment model based on probability output is constructed.The safety risk level of each monitoring unit of the foundation pit is comprehensively evaluated from the probability of occurrence of risk and the degree of risk loss,and the dynamic quantitative calculation of risk is realized..(4)The development of deep foundation pit safety risk warning plug-in based on Revit.Taking the results of GA-SVM risk assessment model as the data source,the plug-in of foundation pit safety early warning is designed and developed by using C # language and Revit API.The automatic calculation,dynamic update and visual display of risk assessment results are realized.(5)Combined with the specific engineering case,the feasibility of risk assessment model and early warning plug-in is verified,which shows that the method is scientific and practical.