Test on impact vibration transmission and attenuation characteristics of low vibration track

Aiming at the problems of excessive deformation and easy failure of elastic components in the application of low vibration track (LVT) for the heavy haul railway, the bearing block was optimally designed. The short side slope was adjusted from 1: 17. 00 to 1: 4. 85, the backing board under the bearing block was removed, and the elastic rubber boot was integrated. The traditional LVT and improved LVT full-scale models were established to verify the design results. A wheelset with a mass of 1 120 kg was used to carry out the drop impact test at a drop height of 20 mm. The transmission and attenuation characteristics of vertical vibrations of rail, bearing block, track slab, base slab and ground along the longitudinal, vertical and lateral directions of track under the impact were compared and analyzed from the aspects of time domain and frequency domain, respectively. Research result shows that the high frequency vibration energy generated by the wheel-rail impact transmits along the longitudinal direction of track, and the low frequency energy transmits to other track structures. The vertical impact vibration attenuates continuously in the process of longitudinal and vertical transmissions, and the attenuation rate decreases gradually. In the lateral transmission process of vibration on the surface of bearing block and track slab, the transmission vibration to the outer edge increases. Compared with the traditional LVT, the whole elastic coefficient of improved LVT decreases by 21.1%, while the damping coefficient increases by 5.4%. The vibration period, attenuation time and acceleration peak of improved LVT reduce by 37.0%, 21.3% and 3.4%, respectively, and the power spectral density peak of each structure component is more than 30% smaller than that of traditional LVT. The Z vibration level at each track structure component of improved LVT is smaller than that of traditional LVT, and the Z vibration level at the ground reduces by 3. 65 dB. It can attenuate the wheel-rail impact force and track structure vibration more effectively and rapidly. The vibration level is lower, and the impact effect on the environment reduces. The research result serves good references for the vibration reduction performance test verification, optimization and engineering application of LVT. © 2020, Editorial Department of Journal of Traffic and Transportation Engineering. All right reserved.