轨道刚度不平顺对高速车-轨-桥系统振动的影响

Influence of track stiffness irregularity on dynamic behaviors of train⁃track⁃bridge system

轨道刚度不平顺从轨面上难以区分,当列车通过时则会产生巨大的轮轨冲击或轨道变形,严重影响系统的安全平稳运营。针对该问题,首先解析推导了轨道刚度不平顺的数学表达式,并基于列车-轨道-桥梁动力相互作用理论建立了高速列车-板式轨道-轨桥耦合动力学模型;在此基础上从时域和频域角度研究了常规型轨道刚度不平顺对系统的影响;并以扣件失效为例,研究了缺陷型轨道刚度不平顺对系统动态特性的影响规律。结果表明:轨道刚度不平顺对系统振动有明显影响;轮轨力、轮对加速度及构架沉浮加速度等列车振动响应明显,表现出扣件间距及轨道板长度的周期性影响;在所考察的指标中,构架点头加速度对轨道刚度不平顺最为敏感;当考虑结构弹性后,轨道板边缘位置处的振动较板中位置处的振动大,两位置处钢轨加速度幅值比为1.17,而轨道板的加速度比值则达到了2.2;常规型轨道刚度不平顺主要引起结构周期振动,可能导致系统共振,加速结构损伤;缺陷型轨道刚度不平顺会造成轮轨冲击,严重时导致轮轨垂向力和轮重减载率超标,威胁行车安全;列车在250~350 km/h之间速度运行时,失效扣件的数量最多为1个。

Track stiffness irregularity,indistinguishable on rail surface,causes dynamic impact or track deformation when trains running through,which greatly affects the operation safety and stability of the system.In view of this practical issue,a determination method of track stiffness irregularity was analytically deduced.Then,a high⁃speed train⁃track⁃bridge dynamic interaction model was established based on the train⁃track⁃bridge dynamic interaction theory.On this basis,the influence of normal track stiffness irregularity on the dynamic behaviors of the system was investigated in time and frequency domains.Finally,taking the fastener failure as an example,the influence of abnormal track stiffness irregularity on the dynamic performance of the system was studied.Results show that track stiffness had obvious effect on the vibrations of the system.Wheel⁃rail force,wheelset acceleration,and vertical acceleration of frame were obviously influenced by fastener spacing and length of slab.Pitch acceleration of frame was most sensitive to track stiffness irregularity.Considering structural elasticity,track vibrations at the slab⁃edge were much larger than those at the mid⁃span.The amplitude ratio of rail acceleration at different locations was 1.17,while that of slab acceleration reached 2.2.Normal track stiffness irregularity caused periodical vibrations,which might lead to the resonance of the system and speed up the structure damage,while abnormal track stiffness irregularity caused wheel⁃rail impact and affected the running safety of the system in serious situations.When the train ran at 250-350 km/h,the allowable number of failure fastener was one.