Displacement Back Analysis And Primary Support Reliability Analysis Of Deep Tunnel

With the rapid improvement of national infrastructure and further development of China's Western Development Program, highway, railway and underground projects are all developing rapidly. A large number of long and deep tunnel projects are launched one after another. At the same time, New Austrian Tunneling Method of information dynamic design and construction technology are getting more and more attention. This thesis is based on Gonghe tunnel project which is under construction, rock behaviour and primary support's reliability of deep tunnel are analysed. Combined with monitoring measurement in the tunnel, following areas are researched in this thesis:â‘ Monitoring measurement in tunnel, back analysis method and reliability's research status are analysed and summarized, main research contents and technical routes are given.â‘¡The basic principles of Artificial Neural Networks , learning rule and advantages and disadvantages of BP network's are summarized, and appropriate improvement methods are given. Basic theories on reliability are listed, and the main steps of displacement back analysis based on neural network are confirmed.â‘¢The New Austrian Tunneling Method is briefly introduced, and the laws of convergence of the surrounding rock displacement, axial force of anchor bolt, contact stress and I-stress during the excavation of the tunnel are carried out combined with monitoring measurement.â‘£Based on K43+170 section's field-test data in deep buried of Gonghe tunnel, using ANSYS finite element program to simulate, the learning and training samples of BP neural network are established. Using BP neural network toolbox in Matlab compile program, Parameters of Surrounding Rock are calculated by back analysis.Using basic principle and methods of structural reliability analysis, the limit state equation of tunnel initial support's reliability analysis is established. Using Probabilistic Design System in ANSYS, Monte Carlo Method was selected to make sample calculation for 8000 times. The reliability of integral primary support in tunnel is analysed and evaluated.