Risk Assessment Of Highway Tunnel Portal Section Construction Based On Fuzzy Neural Network

The highway tunnel portal section is an important part of the tunnel construction.Generally,the opening buried deep is shallow,and the decency of its surrounding rock of is serious.if it rains frequently,the accident such as the scope of slope instability and the collapse at tunnel face often takes place,which can have a bad effect on the construction progress and engineering safety.Therefore,the portal section construction stage has been considered as a key point of tunnel construction in highway tunnel engineering,if the portal section construction stage of the security risk assessment can be done,we will to be able to detect the effective measures to reduce the probability of risk and reduce the consequences.Thus the construction safety can be protected.Based on the highway tunnel engineering whose portal section is shallow and surrounding rock is 5 grades and the fuzzy neural network method,the risk probability estimation model of the construction section of the tunnel is established,and the model is applied to the tunnel of the Baohan Expressway in the risk assessment of the portal section construction stage.the result is as follows:1)Because the traditional risk assessment method with great uncertainty and limitation is full of subjective factors,the fuzzy neural network method is put forward,which combines fuzzy mathematics theory and neural network theory.Based on the engineering research and research on the latest achievements at home and abroad,this paper uses the expert investigation method to identify the risk and risk factors in the construction stage of the highway tunnel entrance section.Then risk assessment index system of construction stage of highway tunnel portal section is built by using the analytic hierarchy process.2)In the application,based on the learning samples of the fuzzy neural network,and the risk assessment index system of construction stage of highway tunnel portal section,the sample data is established by using the fuzzy hierarchy comprehensive evaluation method and the related data.3)This paper constructs the risk probability estimation model of the construction stage of highway tunnel portal section with the fuzzy neural network method as the basic method,which uses the MATLAB software.The probability level of the risk occurrence can be determined by the model.The risk consequence estimation model is established by using the consequence equivalent method to determine the consequence level of risk occurrence,and the risk comprehensive rating can be evaluated by using the"R=PxC"method.4)The risk probability estimation model and the risk consequence estimation are maked use of the tunnel portal section of the Baohan Expressway to process the risk probability estimation.In line with the risk level standards of the construction stage of highway tunnel portal section,we processed the comprehensive evaluation and put forward the effective treatment measures to ensure the safe construction of the tunnel.5)This paper uses the finite element software MIDAS/GTS to carry out numerical simulation analysis of the construction stage of a tunnel in Baohan high speed.Based on the results of this risk assessment and the risk management measures,a new numerical model is established.The original model is compared with the optimization model after the risk model and the actual monitoring measurement results to confirm the feasibility of the risk management measures and the accuracy of the construction stage of highway tunnel portal section’s risk estimation model based on the fuzzy neural network.