弹性支承块式无砟轨道冲击振动传递衰减特性试验

针对重载铁路弹性支承块式无砟轨道(LVT)在实际应用中出现的弹性部件变形过大、易损坏等问题, 优化设计了既有弹性支承块, 将支承块短侧边坡度由1∶17.00调整为1∶4.85, 取消了块下垫板, 并采用一体化弹性套靴; 为验证设计成果, 建立了传统型LVT和改进型LVT足尺模型, 采用质量为1 120 kg的重载货车轮对, 以20 mm的落高进行落轴冲击试验, 分别从时域和频域角度对比分析了冲击作用下竖向振动在钢轨、支承块、道床板、底座板及地面等结构部件沿线路纵、竖、横向的传递衰减特性。研究结果表明: 轮轨产生的高频振动能量沿钢轨纵向传递, 低频振动能量传递给下部其他轨道结构; 竖向冲击振动在纵、竖向传递的过程中不断衰减且衰减速率逐渐降低, 在支承块和道床板表面横向传递过程中, 向外侧边缘传递振动增大; 相比传统型LVT, 改进型LVT整体弹性系数减小21.1%, 而阻尼系数增大5.4%, 其振动周期、衰减时长、振动峰值分别比传统型LVT小37.0%、21.3%和3.4%, 各结构部位功率谱密度峰值比传统型LVT小30%以上; 改进型LVT轨道结构各部位Z振级比传统型LVT小, 在地面处减小了3.65 dB, 能更有效、迅速地衰减轮轨冲击力和轨道结构振动, 振动水平更低, 降低了冲击作用对环境的影响。研究结果对于开展LVT减振性能试验验证、优化与工程应用有参考价值。 

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.