The Research On Project Risk Analysis Based On PERT

As one of the three control targets, schedule control has been regarded as the keypoint and get highly attention. If the construction period is greatly delayed, it will affect other two goals, not only may cause social resources in serious waste, project quality is also under influence in various degree. Instead, in case that the construction period is in advance progress, the project will put into operation in advance, which would produce a direct economic benefits. But the characters of large civil engineering projects are:having a substantial investment, complex technique and economy, longer construction period, actual construction environment must be different with the assumed various factors, the uncertainty factors have more opportunity to come out, which means the probability of schedule risk is higher relatively. Therefore, using risk management on project schedule plans and taking effective measures to reduce risks and losses, will be effective means to control the project period, achieve the goal of project,guarantee large-scale construction operating smoothly.At engineering construction field, PERT (Program Evaluation and Review Technique, PERT) is used widely in making project schedule and progressing risk analysis, domestic and foreign researches on PERT are strenuous. Aiming at the issue of PERT, there are some positive results such as:activities duration of distribution, activity duration calculating, the probability distribution of risk factors and construction period, key route, completed probability calculation and so on. But there are still many problems worth to continue to explore. Therefore, based on PERT network, this paper takes risk factors and network activities as the research object, through risk identify and estimate of activities, constructes random sampling method of activity duration based on probability model of risk factors, builds network model based on risk factor quantitative, then figures out the model with Monte Carlo method, improves the traditional progress to solve the schedule risk, not only can get regular macro indexes such as completed probability, key degree of lines, but also constructs Risk factors-period linear correlation coefficient (Risk critical Index, RCI), improved method fully embodies and utilizes the risk analysis results. At last, validates the feasibility of this modle by a example, meanwhile indicates that RCI can quantify risk factors influence level, which provides reliable basis for the highlighted management of project schedule risk.