Safety Risk Assessment Of The Influence Of A Subway Shield Construction On Adjacent Pipelines

With the continuous advancement of urban construction in Dalian,the problem of traffic congestion has become a prominent problem that hinders the development of the city.Therefore,the construction of underground rail transit has become the primary construction project to relieve traffic pressure.At present,shield tunneling is generally used for tunnel excavation in Dalian subway construction.However,due to a series of factors such as poor geological conditions,the previously constructed urban pipe network system and construction management,the safety of Dalian subway shield construction has become a smooth project.The implementation focuses on the goals.This article relies on the section 7of Dalian Metro Line 5 to conduct a risk assessment of the degree of safety risk caused by shield construction induced damage to adjacent pipelines.The specific work content is as follows:(1)Analyze the internal factors such as personnel factors,pipeline quality factors,equipment and construction technology,and institutional factors in shield construction,as well as environmental factors such as geological conditions and hydrological conditions,and then identify the cause of the accident from multiple angles in combination with the field conditions of the project.Identify 38 secondary risk factors and obtain an initial list of risk factors.In order to achieve the effect of reducing unnecessary risk factors while restoring the risk factors in the actual project,propose valuable countermeasures to make each primary risk only With three key secondary risk factors.(2)Quantify the attributes corresponding to each risk factor through the questionnaire data,use the improved Topsis method to organize the data to obtain the initial decision matrix,and calculate the proportion of each second-level risk factor under the same first-level risk factor;and then obtain the risk factor According to the contribution degree and entropy value under different attributes,combined with the weighted distance squared and the size of each secondary risk,12 key risk factors are obtained.(3)Construct a fuzzy Bayesian network model based on the risk factors selected by the Topsis method above,and obtain the prior probabilities and conditional probabilities of the root node,the intermediate node and the leaf node through the questionnaire;use the fuzzy Bayes formula to calculate The defuzzification probability of the leaf node in different states;the sensitivity calculation of the root node is made according to the different states of the leaf node,and the corresponding preventive measures are formulated to provide an effective reference basis for the shield construction of Dalian Metro Line 5.