Study On Risk Identification And Evaluation Of PPP Project In Urban Underground Pipe Gallery

With the rapid development of urbanization,more and more people are pouring into the cities,which demands the higher carrying capacity of the cities.However,the infrastructure is not enough to meet the demand.Problems such as road zippers and urban cobwebs still exist.In this way,the government vigorously promotes the construction of underground pipe gallery in order to improve the quality of urban development,meet the needs of the social demands and create a new and efficient urban landscape.Nevertheless,the construction of underground pipe gallery and the application of PPP mode in our country is still at the primary stage.Although mature technique are available for reference,the practical experience in our country is still insufficient.In the process of large-scale construction,there are bound to be potential risks.And identifying the risks of the PPP project in the underground integrated pipe gallery and evaluating its risks will be conducive to its healthy and stable development.This paper firstly reviews the relevant literature about the underground pipe gallery PPP project,clarifies the related concepts and characteristics,summarizes the risk categories,risk identification methods and risk identification results of the underground pipe gallery PPP projects,and analyzes the advantages and disadvantages of each risk evaluation method and its application,finally get the index system of risk indicators,which contains 53 risk indicators with 3 levels and 6 aspects.In the case of limited literature and data available,use scenario analysis method which is divided into five steps:clear the focus of problem,identify key risk factors,determine the scene variable and establish uncertain axes,develope scenario logic,and analyze scenario content to analyze the possible future development trend of the project and identify risks in depth with both overall and partial perspectives.Four types of scenarios are ultimately developed:risk-free scenarios,technical risks,policies and environmental risks,and overall risks.As the project risks are fully identified,this article uses set pair analysis method to evaluate the risk of the project.Based on the established risk index system,the risk level is divided by the risk matrix and the risk degree function to determine the risk value and risk level of each risk index.The group eigenvalue method is used to determine the weight of the indicator.Then make use of the IDO based on the change of trigonometric function to calculate the connection degree between the risk degree of each index and each risk level.And combined with the index risk degree value,evaluate the overall risk of the project by multi-level GSPA.The results show that the social stability,existing construction technology reliability,land subsidence,environmental pollution,and uncontrollable quality of operation and maintenance are at a low risk level,and the rest of the risk indicators are at medium risk level.In addition,the risk level of management risk is between the lower and middle,the risk level of the other risk is medium.After comprehensive judgment,the underground pipe gallery PPP project is at medium risk level.Finally,based on the results of empirical analysis,put forward some suggestions from different aspects.