Risk Assessment In Tunneling Project By Imprecice Probility

Due to the inherent uncertainties in ground and groundwater conditions,tunnel projects have to face potential risks,such as accident,cost overrun and schedule delay.Risk analysis had became a required tool to identify and quantify risk,as well as visualize causes and effects,and the course(chain)of events.At present,almost all risk assessment and analysis methods are based on the methodologies with precise probability.However,because of limited information or experience in similar tunnel projects,available evidence in risk assessment and analysis usually relies on judgments from experienced engineers and experts.As a result,imprecision is involved in probability evaluations,which results the inaccurate in risk assessment and analysis.In this paper,the event tree analysis method,the fault tree analysis method and the decision tree analysis method based on imprecise probabilities had been established for the risk assessment of tunnel projects.And then,the Wuhan Metro Line 2 Yangtze River Tunnel Project were taken as an example to use the above approaches for risk analysis and assessment,and the outcomes were compared with the outcomes from the traditional approaches with precise probabilities.By compareing the imprecise probability method and the precise probability metho,the main outcomes in this paper are as follows:(1)In the case of the potential risk assessment of Wuhan Metro Line 2 Yangtze River Tunnel Project,it was found that the results obtained by the event tree evaluation with imprecise probability were more accurate than those obtained by the event tree evaluation with precise probability.(2)In the case of the environment risk assessment of Wuhan Metro Line 2Yangtze River Tunnel Project,the result obtained by fault tree evaluation with precise probability was negligible,which is inconsistent with the actual situation of the project.While the result obtained by fault tree evaluation with imprecise probability is consistent with the actual situation.(3)In the case of the necessity and the type of additional exploration for WuhanMetro Line 2 Yangtze River Tunnel Project,it was found that the results obtained by the decision tree evaluation with imprecise probability were more comprehensive than those obtained by the decision tree evaluation with precise probability.From this paper,it is concluded that the the results of risk assessment using imprecise probability method are more accurate and more consistent with the actual situation than the results of risk assessment using precise probability.