Risk Analysis For The Rock Of Tunnel Based On The Bayesian Network

During construction of the tunnel, safety has been focus on the construction of tunnel,it's value to carry out the risk analysis to improve the safety of the tunnel and to predicate the risk.In order to analysis the tunnel's risk in the construction,this paper based on the theory of bayesian network, the mathematical statistics and the results of the finite element simulation was used.the bayesian network risk analysis models for the classify of the rock and stability of the initial rock-support has been built, and it set up an expert system for forecasting and reducing risk and determinating quickly during the contruction of the tunnel base on the network.lt achieves the fast identification and determination for the risk of the tunnel.This paper researched the rules of the risks and the stability of the tunnel which occurred during period of the construction tunnel, the main contents include the following aspects:First, the main risk problems were analyzed for the tunnel construction and determined the factors which affected classification of rock and the stability of initial rock-support.This paper expounded the basic principle of bayesian networks and the feasibility of risk analysis, and set up a bayesian network for risk analysis and their relationships between them.Second,classify of rock has been statisticed from the built-tunnels.And we got the prior probability which influence Q classification and [BQ],and based on the statistical data to set up the bayesian network models about the classify of rock,by use of the models, bayesian network models can make a rapid judgment for the level of rock.And we can be predict the unknown variables by the known variables of the tunnels.Third, we usethe finite element software to simulate the excavation of the tunnel and to support process.we got the formulas which can express the relation between the strength parameters of the rock and stress of supporting, and set up the bayesian network models.By the analysis of the model and adjustment, we obtained probability about instability of supporting,and if we changes the state of the variables in the network, other variables will change, through this change we can find various factors rules between them.Forth, an expert system has been set up which use to choose the right construction methods, we collected a lot of datas which came from the built-tunnel, and inputed these data to the system.We set up the tunnel construction method of the system based on the statistical datas and expert experiences.