Large Cross Highway Tunnel Rock Mechanics Parameters And Numerical Simulation Of Dynamic Construction Mechanics

With the rapid economic growth and urban development, requirements on long and large tunnels are increasing with each passing day. Bell-mouthed road tunnels with large-span appear constantly in the urban transportation system. Its characteristics, especially large-span, have caused a series of engineering problems, such as support modes, support parameter, construction methods, stability of surrounding rocks and so on. Thus so far there has been no clear and practical code to guide the design of large-span road tunnel. The accurate calculation and rational design of load should be based on the accurate choice of mechanical parameter. So it is necessary to acquire the mechanical parameter of the tunnel's surrounding rocks by proper methods. As for the construction of bell-mouthed road tunnels with large-span, domestically there is only limited experience for reference. So it is particularly necessary to conduct further studies on the dynamic construction mechanics of the broadened segment. In this thesis, the mechanical parameter of the tunnel's surrounding rocks and dynamic construction mechanics are studied by theories analysis, numerical simulation and field measurement in the broadened segment of the right-way bell-mouth of Henglongshan North Tunnel in Shenzhen. The main research is as follows:(1) Setting two monitoring cross-sections at broadened segment to monitor the deep displacement of surrounding rocks. So as to acquire the numerical value for the settlement of vault and the horizontal convergence of the tunnel due to one-sided excavation. Based on the BP model of Artificial Neural Network, the mechanical parameter of the tunnel's surrounding rocks is back-analyzed.(2) Using the ANSYS software to establish a 3-D model of the broadened segment of the right-way bell-mouth of Henglongshan North Tunnel. Based on its real construction method, the dynamic construction mechanics is numerically simulated.(3) During the excavation, based on the numerical simulation of dynamic construction mechanics, each step's influence on the settlement of the earth's surface is analysed.(4) During the excavation, based on the numerical simulation of dynamic construction mechanics, each step's influence on stresses of the tunnel's vault, arch foot and basement is studied.