Research On Risk Control Of Shield Tunnel Construction In Metro

Since the reform and opening up,China has continuously promoted the urbanization process and increased investment in infrastructure.As a tool for alleviating traffic congestion,the subway has been widely used in major cities.The shield method relies on construction advantages such as high degree of automation and low environmental damage,and has broad application prospects in underground construction.At the same time,due to the characteristics of complicated construction technology,long cycle,complicated surrounding environment,numerous required equipment,and cross-professional work types,subway tunnel projects have caused frequent construction accidents.Therefore,it is imperative to discuss and practice the risk management of subway tunnel shield construction.This article conducts a systematic study based on the results of research on risk management techniques and methods at home and abroad,combined with the characteristics of subway tunnel shield construction and risk management processes,mainly including the following aspects.First,the WBS method is used to decompose the construction of the subway tunnel by using the shield starting,shield advancement,segment assembly,grouting behind the wall,and shield reaching five stages.According to the theory of risk occurrence mode,the RBS method is used to decompose the risk into personnel factors,material factors,equipment factors,technical solutions,and external environment.Through the WBS-RBS matrix,judge the coupling of the elements crossing rows and columns and establish a risk evaluation index system by naming.The principal component analysis method is used to weaken the correlation between risk factors and simplify the risk evaluation index system.Secondly,on the basis of determining the risk grading standards in this paper,the risk indicators are divided into quantitative indicators and qualitative indicators.Quantitative index risk probability and risk loss estimation methods use construction membership function and fuzzy statistics method respectively;qualitative factors use expert scoring method to estimate risk probability and risk loss.Finally,in the risk evaluation,the improved AHP method is used to determine the weights to solve the problems of the traditional AHP method,such as the complicated consistency test and the need for multiple corrections.The improved fuzzy comprehensive evaluation method is used to obtain the risk probability and risk loss.Evaluate the results to solve the problem that smaller weight factors are easily overlooked.Combined with the risk matrix to comprehensively evaluate the risk level,the corresponding control countermeasures are proposed from the perspective of risk factors,pregnancy risk environment,and underwriters for the risk indicators of level I and level II.Based on the construction risk assessment model of the shield tunneling method for subway tunnels established above,an empirical study was conducted on the tunnel between Guanlan Station and Songyuanxia Station of Phase 3 of Shenzhen Metro Line 4,and the relative control measures were formulated based on the evaluation results to verify the applicability of the model,Provides guidance and reference for the application of risk management theory in tunnel engineering.