Research On Vibration Characteristics Of Vibration Reducing CRTS â…¢ Slab Ballastless Track

In order to support the strategy that our country exports its railway technology to overseas, and address vibration and noise and other environmental issues caused by high-speed train, researching on the anti-vibration characteristics of CRTS III ballastless track with the Chinese independent intellectual property rights is meaningful to engineering application. This paper takes the anti-vibration CRTS III ballastless slab track as the research object. Aaccording to vibration theory and vehicle-track coupling dynamics theory, two-dimensional composite beam model in frequency domain and three dimensional vehicle-track-transition section vertical coupling model in time domain were founded respectively. With the method of ANSYS and ANSYS/LS-DYNA, researches on the vertical vibration transmissibility of anti-vibration CRTS-III ballastless slab track in frequeney domain and its vibration characteristics of on subgrade-tunnel transition section were carried out.Firstly, based on the structural characteristics and compositions of anti-vibratoin CRTS-III ballastless slab track, the track components have been simplified reasonably in accordance with the finite element theory. And the beam-solid finite element model and two-dimensional composite beams model were established. Using the modal analysis and harmonic response analysis to solve the finite model above, the calculation results indicated that fastener stiffness has little influence on the natural frequency of the track, while the thickness of slab and area rigidity of anti-vibration pad have much influence on it. Taking transmit function(receptance) for evaluation index, the analysis about the influence that the parameters of anti-vibration pad have on transmission properties was carried out. Surface damping of anti-vibration pad mainly has an impact on reducing the resonance peak, but surface stiffness of anti-vibration pad makes a difference to changing the frequency range for vibration reduction.Secondly, viewing the vibration isolation efficiency as the evaluation index, this article based on vibration theory analyzes the impact that the parameters of slab track system have on vibration isolation efficiency. The calculation results indicated that the fastener stiffness has little influence on vibration isolation efficiency, while the parameters of slab and anti-vibration pad have much influence on it. In the perspective of highly enhancing the vibration isolation efficiency of track system, the calculation results indicated that when the anti-vibration pad surface damping is 0.1MNs/m3～0.25MN·s/m3are appropriate, on the premise of safe driving, a smaller surface stiffness of anti-vibration pad is appropriate.Finally, based on the vehicle-track coupling dynamics theory, the anti-vibration pad was simplified by spring-damper, and the vehicle-track-transition vertical coupling model was established. The calculation results indicated that the hierachical stiffness of anti-vibration pad can be applied in the subgrade-tunnel transition section, the stiffness ratio should be no more than 2. Viewing the change rate of rail vertical deflection as the evaluation index, in order to ensure running safety and reduce the workload of maintenance and repair on subgrade-tunnel transition section, the length of subgrade-tunnel transition section should be within the range of 25-30m.