Research On The Risk Assessment Methods And It’s Application In Subway Construction Period

Subway construction project has characteristics such as complexity, strong concealment, involving a number of uncertainties, large scale of investment and construction, many potential risk factors. At the same time, once subway project hazard occurs, not only can lead to heavy economic losses and great casualties, and will also cause bad social and political influence. Therefore, it is very necessary to do a comprehensive and in-depth research of subway risk assessment.Based on the study of subway construction period risk mechanism, the main risk factors are qualitatively analyzed and identified by the methods of expert investigation and check table in this paper, the risk index system is established too. Then, the expert experience method is used to determine the membership grades of risk factors. Combined with weights of all risk factors determined by using analytic hierarchy process method, the risk assessment model based on fuzzy synthetic evaluation method is established. Finally, the scientificity and rationality of this risk assessment method is validated through the project case. The main contents of this paper are as follows:(1) Combining the characteristics of subway construction project, related theoretical background of subway construction period risk assessments is elaborated. First, in the fundamental theory of risk, the definition, characteristics and classification of subway construction period risk are elaborated; secondly, concepts of risk identification, risk estimation and risk evaluation are briefly introduced in the fundamental theory of risk assessment; then the risk classification standards and acceptance criteria of subway construction are given; finally, the article briefly introduces the basic theory of fuzzy mathematics.(2) Risk identification of subway construction period based on experts investigation and check table method. The risk occurrence mechanism of subway construction period is firstly introduced; and then the common risk identification methods are given. On this basis, expert investigation and check table method are used to obtain the main risk factors.(3) Risk assessment of subway construction period based on fuzzy synthetic evaluation method. The main risk assessment methods are discussed, analytic hierarchy process and fuzzy synthetic evaluation method are focused on too. The fuzzy synthetic evaluation method is selected as the subway construction period risk assessment methods and the risk assessment model is built:first, the risk probability and loss factor sets are established on the base of the risk identification result, the evaluation sets are established through fuzzy mathematics theory. And the expert experience method is used to get the membership grades of risk factors; besides the subway construction period risk evaluation index system is built through AHP; confirm relative index weight of each level with1-9scales method. At the end, using weighted average model fuzzy operator to assess the frequency and consequence, meanwhile, the risk classifications are worked out.(4) Project application. The risk assessment method built in this paper is applied to Guangzhou rail transit Line9, and the assessment conclusions fit in nicely with actual project situation; what’s more, this paper give the risk control measures based on actual project and risk assessment results, provide important reference for the subway construction.