青藏铁路轨道不平顺界限谱研究

Research on Track Irregularity Boundary PSDs of Qinghai-Tibet Railway

为了给青藏铁路养护维修、动力评估提供更为科学合理的车辆-轨道系统激振源和评判依据,基于青藏铁路较为充实的实测数据(累计里程为9.23万km),对其轨道不平顺谱展开系统研究。采用修正的周期图法分析青藏线的实测轨道不平顺数据,提出能够表征青藏线不平顺特征的统一谱密度函数拟合公式,得到了青藏线轨道平均谱的特征参数。基于谱密度的概率分布特性,给出了直接通过谱密度转换系数获得任意累计概率水平下轨道谱的方法。经过与国外常用轨道谱密度分布特征和动力仿真结果进行比较,论证了青藏线轨道不平顺统计平均谱的保守性,结合车辆-轨道耦合动力学理论,提出了轨道不平顺界限谱的动力学制定方法,计算获得了行车速度-动力指标限值下的青藏铁路界限谱及其参数。

In order to provide appropriate excitation sources and evaluation criteria for the maintenance and dynamic evaluation of the Qinghai-Tibet railway,this paper conducted systematic research on track irregularities PSD based on sufficient measured data that covered about 92 300 kilometers of Qinghai-Tibet railway.A modified periodogram method was applied to analyze the measured track irregularity data of the railway and a unified PSD fitting formula that can characterize the basic irregularity characteristics of the railway was proposed to obtain the characteristic parameters of average PSD of the railway.According to the characteristics of probability distribution of spectrum densities,a transformed method was presented,through which the PSDs with arbitrary cumulative probability levels can be directly acquired upon average PSDs and transformed conversion coefficients.By comparisons with PSD distributions and dynamic simulations commonly used in other countries,the conservatism of average PSD of the Qinghai-Tibet railway was demonstrated.Based on vehicle-track coupling dynamics theory,a new dynamic method for formulating track irregularity boundary spectrums was proposed,to obtain boundary spectrums of the Qinghai-Tibet railway and its parameters under vehicle speeds and dynamic indexes＇ limitations.The research results show the efficiency of the methods proposed in this paper,especially the approaches confirming track irregularity boundary spectrums using vehicle-track dynamics,which provide new ideas for the research of track irregularity spectrum.