Stability Analysis Of Soft Fractured Surrounding Rock Mass And Optimization Analysis Of Initial Branch Structure Of Tunnel

China is a mountainous country in which the build of highway tunnels become the key of the construction and development of mountainous cities.In order to ensure the process of the project and guarantee the safety of the constructors during the construction of the tunnel project,a most vital problem that how to reduce the relaxation of the surrounding rock,timely and effectively control the development of the relaxation of the surrounding rock and adopt effective support structures and means to control the reduction of self-bearing capacity of the surrounding rock,is tremendously needed to be settled.Therefore,it is of great significance for the construction of the tunnel to carry out the research of structural stability and optimization analysis of initial branch structure.This thesis is based on the research background of the XiaoBei Mountain No.1 tunnel of the Jie(Yang)-Hui(Lai)Expressway Construction Project in Guangdong Province,the influence factors of the stability of surrounding rock and the support of the tunnel are systematically studied with the core of the dynamic relationship between the support and surrounding rock.Four characteristics of the deformation and force of the tunnel supporting system are analyzed and optimization guidance is carried out by utilizing the field measurement data combining the interaction relationship of the support and surrounding rock.Besides,combined with the BP neural network,inversion analysis based on displacement measured is performed with a comparison of numerical analysis results by utilizing simulation software.Furthermore,the error between numerical displacement result and the measured displacement is calculated and its source of the BP neural network is analyzed as well.In addition,the supporting system is optimized by using the final predicted value of the measured displacement in view of the inversion analysis.The result in this article reveals that the mechanical property of the surrounding rock and the supporting structures are affected by multiple factors that in the initial branch structure experiment the single initial support & the long anchor deformation's control perform more dominant advantage than the two double lining,while the double initial branch is the worst.However,highest stress occurs in the long anchor operating condition.It is worth increasing adequately the length and radius of the anchor,the thickness of the initial branch or changing the initial branch material to strengthen the initial branch for the implement of the construction scheme optimization.The conclusion of the Orthogonal experimental design is adopted to train the neural network during the inversion analysis of the surrounding rock parameters.Finally,an optimized control method of the deformation of the tunnel surrounding rock is established with the base of the neural network and the parameters of the monitoring and measurement displacement.