Analysis Of Vibration Response Of Different Ballastless Tracks Structure On Vehicle-Track Coupling System

Urban public transport, especially the metro, has been called “green transportation” for the advantages of large capacity, less pollution, high efficiency, high safety and comfort performance, it improves the transportation environment effectively. However, many environmental vibration problems are caused by subway. More and more tracks have been used in underground traffic which have excellent effect on reducing the vibration. Therefore, it’s very important to analysis the vibration property of different type ballastless tracks, in order to optimize the vehicle and track structural components and design parameters for reducing vibration of wheel/rail system.Based on the vehicle-track coupling dynamics theory, the vertical analysis models for monolithic concrete bed track, slab track and floating-slab track are established. The dynamic differential equations of vehicle were derived respectively from the D’Alembert’s principle; the dynamic differential equations of the rail, slab and floating slab were created base on the bending dynamics of beam. The interaction force between wheel and rail can be defined by Hertz nonlinear elastic contact theory. Those equations were expressed with mathematical matrixes at last. A new explicit integration method is used to obtain the numerical results of the system equations with the harmonic irregularity as the external excitation. The influence of three types tracks structure on the vehicle dynamic response are analyzed under condition of different train operating speeds, depth and wavelength of track irregularity.The influence relationship of the ballast track structure parameters of fastener stiffness and damping, stiffness and damping under slab on vehicle and track dynamic response are analyzed. The results indicate that these parameters are not as simple as the bigger the better, should be considered with various factors.A two-dimentional model of tunnel-soil is established to analyze the vibration of pavement with different distances and the effect of tunnel depth on pavepent vibration by vehicle running at last. Results reveal that the vibration presents attenuation trend with the increase of distance and tunnel depth.