Risk Analysis Of Metro Tunnel Construction Based On Fuzzy Dynamic Fault Tree Analysis Method

With the rapid development of urbanization, subways are being or will be constructed in most large cities to solve the traffic problems. In urban subway construction process, there is a long construction period, complex safety management,safety risk factors such as fuzzy variable problem. However, now the lack of complete risk management and risk assessment system, the high frequency safety accident happen in the process of urban subway construction. According to the above problem, this paper uses the fuzzy theory and the fault tree analysis method to study the process of urban subway tunnel construction risk.First of all, this paper introduces in detail the term is commonly used in the fault tree analysis method and symbols, features and steps, the qualitative analysis and quantitative analysis, at the same time introduced the concept of fuzzy set and membership degree in fuzzy mathematics, the extension principle, ? cut set and RL- convex fuzzy sets. Used the fuzzy door operator instead of the traditional logic gate operator is to calculate fuzzy importance degree of the fault tree.Secondly, the existing of the fault tree analysis method have disadvantages. In subway tunnel construction process risk analysis apply the fuzzy fault tree analysis method. This method is to use the fuzzy number to represent the event occurrence probability. According to the problem of multiplication of fuzzy numbers, a new method of solving fuzzy number multiplication is derived by using the representation theorem in fuzzy mathematics. The probability of bottom event occurrence is obtained by using the method of expert confidence index and triangular fuzzy number correction. Based on fuzzy fault tree analysis method, the fuzzy uncertainty of the risk factors of engineering construction cost is considered. Through the case analysis,we can know that the two risk factors, such as “leakage of water and grout when the shield enters and leaves” and “encountering obstacles during advancing”, are the most critical of the risk factors, which should be attached great importance to and avoid.Finally, the traditional fault tree analysis method generally does not take intoaccount the dynamic failure characteristics of events and events as well as the fuzzy uncertainty of the data collected in the actual project. In this paper, based on the fuzzy Markov model, the dynamic fault tree analysis method is applied to the analysis of the failure of the shield machine tool panel in the subway tunnel project. Then the dynamic fault tree model is transformed into fuzzy Markov model. By using the extension principle of the fuzzy mathematics and laplasse transform and laplasse inverse transform of integral transformation are used to solve the equations. Then gives two kinds of graphics, one is the failure probability curve of a given time panel,the other is the failure probability curve of fixed cut set panel. Through the graphic analysis shows, when the shield machine cutter panel is working hours to reach 900 number, the failure probability of panel reaches the upper limit. We need to carry out an inspection and maintenance.