Analysis On Vertical Dynamic Responses Of The Vibration Attenuation Double Block Ballastless Track Layed On Bridge

With the improvement of high speed railway traffic speed, the vibration problem of vehicle, ballastless track and foundation is very outstanding. For environmentally sensitive area, the influence of vibration problem is particularly serious. The vibration attenuation double block ballastless track layed on bridge is one of the most important of high speed railway in our country. So, there is very important practical significance to study and discuss deeply on the dynamic characteristics of the vibration attenuation double block ballastless track layed on bridge.Based on the collecting and organizing of the existing research result inland and abroad, This paper established vehicle-car-track-bridge vertical dynamic analysis model, using ANSYS/LS-DYNA software modeling it, then studied the vertical dynamic characteristics of vibration attenuation and normal structure under the condition of not smooth. Taking fastener stiffness and damping, cushion blocking stiffness and damping, traffic speed as influence factors, then expending vertical dynamic characteristics analysis to the vibration attenuation double block ballastless track layed on bridge. Main results as follows:(1) Vibrationattenuation double block ballastless track has bit little impact on vertical vibration of car bodys. But due to the adopting of cushion blocking, the bearing stiffness of the upper structure of track declines, both vertical acceleration and vertical displacement of rail and roadbed slab has markedly increased, and the vibration of roadbed slab increased seriously. The adopting of vibration attenuation double block ballastless track on bridge made the vibration transimitting from track structure to bridge get effective weaken, the vertical acceleration of bridge reduced significantly.(2) The stiffness of fastener and cushion blocking has significant effect on the vertical dynamic characteristics of the line. With the changing of the fastener and cushion blocking stiffness, the change amplitude of vertical displacement of rail and roadbed slab, vertical acceleration of bridge isbigger, suggest fastener stiffness chosing 40.5-49.5kN/mm, cushion blocking stiffness chosing 0.054-0.066N.mm3.(3) The damping of fastener and cushion blocking has significant influence on the wheel-rail force of the system and the vertical acceleration of bridge, suggest fastener damping chosing 36-44N·s/m, cushion blocking damping chosing 45～55N·s/m3.