Risk Identification,assessment And Prediction Of Subway Shield Construction

In order to adapt to and meet the needs of urban innovation and development,China’s urban subway construction has entered a golden period of rapid development.Shield construction can give full play to the advantages of high automation of shield machine,high construction efficiency,and strong ability to deal with complex construction environments.but at the same time,shield construction also has high construction intensity,difficulty in grasping mechanical equipment,and complicated changes in the construction environment.In order to ensure the project quality,construction schedule and construction safety of urban subways,we have provided scientific decision-making for subway shield construction risk management.This article has conducted the shield construction risk management from the aspects of risk identification,risk assessment,risk prediction and risk response.Detailed research,main research work and results achieved are as follows:First,we defined the concept of the shield construction risk as two parts: construction process risk and construction equipment risk.Combined with ZTGF’s many years of experience in shield construction projects and relevant regulations in China,the shield construction risk has been comprehensively and systematically identified from the perspective of the entire shield construction industry.Through the comprehensive use of expert surveys,WBS,4M1 E and other methods,the general risk list of shield construction and the risk list of shield construction equipment were determined.Among them,the construction process risk list includes 39 risk events and 108 risk sources;the construction equipment risk list includes135 risk events that may occur in 13 systems of shield machines.Then,the Fuzzy Analytic Hierarchy Process was used to evaluate the shield construction risk level,and it was obtained that the shield departure and shield advancement were level I unacceptable risks,the mechanical equipment and construction preparation were level II unacceptable risks,and the rest were acceptable and The risk can be ignored.At the same time,the weights of risk events of level Ⅰ and Ⅱ were sorted,to get the major risk events.After that,the method of combining Faulty Tree and Bayesian Network model was used to find the correlation between the major risks of shield construction and the fault alarm data of the shield machine,so as to establish the Bayesian Network model.Taking the M subway project as an example,the reverse diagnosis and inference technology of Bayesian Network model was used to find the critical path leading to the risk of shield construction and the important nodes of shield machine failure on the critical path.It was found that the abnormal propulsion pressure alarm,the cutter head drive soft start failure alarm and the man-cutter cutter head emergency stop alarm were the main reasons for the risk of shield construction.An effective method for predicting the shield construction risk and development trend through shield machine alarm data is proposed,and the feasibility of the model is verified by comparison with the actual situation.Finally,through effective risk response management measures and technical measures for important node factors such as the shield machine alarm on the critical path,the purpose of risk avoidance was achieved,and comprehensive and scientific management of subway shield construction risks was completed.It has universal guiding value for standardizing construction,avoiding risks,and guiding follow-up risk management.