Study On The Dynamic Characteristic Of The Cross Shield Tunnel Under Vibration Load Of Train

With the rapid development of high-speed railway and shield construction method, there is a large number of high-speed railway tunnels using shield tunneling method in the urban and mountain areas. Shield tunneling method has the advantage of the high security, high efficiency, high degree of automation and low disturbance to the surroundings of the shield method construction. And a great quantity of tunnels constructed through shield are cross structures, such as, transverse passage-way, starting and ending shafts, pump house and so on. On that account, the research is based on the Shiziyang Tunnel of Guangzhou-Shenzhen-Hongkong Passenger Dedicated Railway. And train vibration load is applied on the model to analy elastoplastic damage and time history of the cross structure of the connecting transverse passage and space-cross tunnel structures in short distance. The main research work and achievements are as follows:(1) The analytical theory and calculation method of train vibration were studied, including the principle of dynamics, concrete damage theory, the decrease theory of concrete strength. The damping of material, the dynamic boundary conditions of the model, and the constitutive relation of concrete damage were stated.(2) To simulate the time and space effect of tunnel entrance, in-tunnel section and tunnel exit, the unique load curve was applied on the model. The vertical vibration load and gravity of train was imposed on wheel axles of the train. The two kinds of force are transferred on the rail. At the same time, velocity field was applied on the train model. This method can effectively simulate the load of temporal and spatial variation.(3) The cross structure of the connecting transverse passage, space-cross tunnel structures in short distance were analysed. And the vibration effect was studied when the train is running in the shield tunnel. Besides, the dynamic response characteristic of tunnel entrance, in-tunnel section and tunnel exit was analysed. Compared with the stress, acceleration and the damage caused by compression and tension(4) Based on the main mechanical properties of operational tunnels, dynamic response of train vibration load was analyzed at different speeds. And the cross structure of the connecting transverse pass was analyzed in some key sections. Finally, the dynamic damage and dynamic characteristics of the structure could be studied.