Research On Safety Risk Asseeement And Its Application In Subway Tunnel Construction

Subway construction is generally located in the center of the city.The construction environment is complex and varied,with large scale,long duration,strong covert,and more involved in the main body,which is bound to cause the project in the construction period of the number of risks and complex types of construction uncertainty and security risks.Therefore,it is of great practical significance to carry out research on safety risk assessment of subway tunnel construction.Based on the independent research and summarization,this paper has carried out the research on the safety risk assessment of subway tunnel construction by means of literature research,field investigation,expert questionnaire survey,statistical analysis and fuzzy mathematics theory.Then this paper tries to carry out the assessment applications of subway tunnel construction risk on the basis of Chengdu Metro Line 5 Phase 1 project.The main work and achievements are as follows:(1)To establish a subway construction accident database.The paper counts 172 typical accidents of the tunnel construction,then analyses the accident and the influencing factors of the typical accidents.Based on the existing research results,the project site survey and the expert consultation,three kinds of the specific risk assessment index system of construction method are established:the cut and cover method,the shield method and mining method.(2)Using the BP artificial neural network algorithm,combined with the fuzzy mathematics theory,the paper takes the risk factor as the input layer content of the neural network and the probability and loss of the risk event as the output layer content of it.And then three kinds of risk assessment mathematical model are established:the cut and cover method,the shield method and mining method.(3)Reference to the subway tunnel construction risk assessment of the relevant norms to determine the subway tunnel construction risk assessment criteria.In order to facilitate the BP neural network to estimate the probability of risk level and loss of risk level,the risk factors of the three kinds of construction methods,such as the cut and cover method,the shield method and the mine method,are quantified by 0 to 1,and the risk probability level and the risk loss level are quantified by 0 to 1,which is based on fuzzy mathematics theory,and combined with subway construction specification literature and scholars research results.And later the paper studies the risk control from the aspects of risk control strategy and risk control measures.(4)Based on SQL Server database and C#language,the safety risk assessment software of subway tunnel construction is developed.The software can store and query the accident information,and also can evaluate the special construction risk of the three kinds of construction methods,such as the cut and cover method,the shield method and the mining method.(5)Apply the research results of subway tunnel construction risk assessment to the construction risk assessment of Chengdu Metro Line 5.The results show that the construction risk level of the foundation pit of the Dongzikou station in Chengdu Metro Line 5 is grade I.The construction risk level of the cross through Xibei bridge and the Fuhe river by the shield method is grade I.The construction risk level of the cross through Tibet branch of Agricultural Bank of China in Chengdu by the mining method is grade ?.The results of this review are consistent with the results of actual situation of the project.