Shield Tunnel Risk Analysis Based On Improved Fault Tree

Metro tunnel construction in our country has made great progress with leap-forwarddevelopment of economic, but with the metro project spread everywhere in large andmedium-sized city, the metro tunnel construction risk management issues are highlightedstep by step. The characteristic of long construction period, random changes, difficultmanagement, risk factors complicated contributed to the safety accident in metroconstruction, seriously threat the national economy development and people’s health, thesubway tunnel engineering risk assessment and early warning needs to be on the agenda.In this thesis, cloud model theory, fuzzy fault tree method and T-S fault tree methodare employed to systematically analysis surface subsidence and failure risk of shield cutter.First of all, this thesis contrast and analysis existing risk evaluation method from the scopeof applicable, propose using fuzzy fault tree and T-S fault tree to evaluate surfacesettlement and failure risk of shield cutter, for the characteristic of uncertainty whichexists in metro shield tunnel. Study shield construction surface settlement risk based onfuzzy fault tree, and analyzes the limitation of traditional fuzzy methods and the feasibilityof the cloud model fuzzification. Based on the fault tree of surface settlement, use cloudmodel to process the transition between qualitative and quantitative language value whenthe expert divide the range of distribution of risk factors. Through the correction of cloudcohesion, it can be more objectively and accurately to determine the probability values ofbasic events and the range of distribution of risk factors, so we can get fuzzy importancedegree of each basic events of subway shield construction surface subsidence and makeprevention measures. Finally, in the case of the failure of shield cutter, introduce the T-Sfuzzy fault tree, use fuzzy possibility to describe failure probability of basic events, so asto solve insufficient information of basic events; Using T-S door instead of traditionallogic gate to describe the relationship between events, so as to solve the problem that therelation between different events is difficult to determine; then we can get the maininfluencing factors of shield cutter failure, to provide reference for troubleshooting andengineering practice.