A Study On Risk Warning System Of City Tunnel Construction Period

In recent years, due to the advantages of smaller occupied area and less environment influences, the tunnel project has been widely applied to many cities and towns, and played a very important role in the construction of mountain city roads and urban rail transit. However, city tunnel projects are disturbed by external effect more easily, and in the face of more constraints and more complex environment, the completions of city tunnel projects are often delayed.When the construction period of a tunnel project is out of control, not only more costs are produced because of the waste of manpower and materials, but also the quality and safety of the project will be effected. Therefore, project managers pay more and more attentions to time risk management of city tunnel project.In this paper, the author briefly introduces the definition of city tunnel project and risk, enumerates the risk factors that make more effects to construction periods. With the factors, an index system and the hierarchy of risk evaluation of the city tunnel construction period are established, risks are evaluated with the method of AHP. Then, a risk warning system of city tunnel construction period is built, which is composed by four sub-systems called risk status, risk identification, risk assessment and risk prediction. In the sub-systems of risk prediction, PERT and Maximum Entropy model are used to calculate the critical path , the risk value of every construction processes be competed in time is calculated,too. On this basis, the time risk indicators and warning alert level are established. In the end, according to the general paradigm of risk response, several programs and specific preventive measures are given.With the method combining qualitative and quantitative analysis, this article establishes a risk warning system of city tunnel construction period, and provides theoretical and technical supports to risk control of the city tunnel construction period.