The Basis Of Status In The Different Rail Train - Track System Of Vertical Vibration Response

With the development of speed-up and high-speed in China Railways, the increase of train and track vibration is inevitable. At the same time, people ask for more comfortable travel by train. Improving track condition and optimizing track structural parameters are the prerequisite to improve bearing capacity of track and to guarantee the running quality. They are also the ways to solve this problem. This dissertation is to find the rules of vertical vibration of train-track system on different sub-rail foundations. The main works and conclusions are as follows:1. The track is discreted as track sagment elements with 12 degrees of freedom(DOFs)for each. Each vehicle is simulated as a multi-rigid body system with 6 DOFs. The vertical vibration equations of train-track system are established which are based on the principle of the total potential energy with stationary value in the elastic system dynamics and the rule of "set-in-right-position" for formulating system matrixes. The equations are solved by Wilson-θstep-in-step integration method and the corresponding computer program is compiled.2. Taking the vertical track irregularity as the exciting source, the vertical vibration of the train-track system on different sub-rail foundations when the train runs at 120km/h is calculated. The rules of effects of some track parameters, such as fastener stiffness, ballast stiffness, the ratio of fastener stiffness to ballast stiffness, distance between two adjacent sleepers, voided sleepers and voided rail, etc., on vibration responses, such as vertical displacements and accelerations of sleeper, rail and carbody, the wheel-rail contact force, the pressure on sleeper, etc., are obtained.3. The calculated results show that the reasonable stiffness of fastener is 4×10~7～7×10~7N/m, the appropriate value of ballast stiffness range from 4×10~7 to 8×10~7N/m, the reasonable ratio of fastener stiffness to ballast stiffness is 0.5～0.8 and the reasonable distance between two adjacent sleepers is 0.575m～0.625m. All of these are useful for track design and maintenance. 4. The effect of voided sleepers and rail on the vertical displacements and accelerations of the sleeper, rail and carbody is great. The voided sleepers or rail will amplify the responses of track structure, accelerate the deformation of track structure, speed up the track deterioration and even do harm to safety. So, detection of voided sleepers or rail is nenecessary. Once voided happened, it should be treated immediately.5. The vertical vibration is closely related to operating speed. With the increase of speed, the vibration responses of the system relatively becomes more obvious, especially the increase of the vibration accelerations.