Track stiffness irregularity is superficially invisible on rail surface, while causes dynamical impact and track deformation when trains running through. Aiming at this issue, this work presents an investigation on the influence of track stiffness on dynamic behaviours of the high-speed vehicle–track–bridge dynamic system. Primarily, a determination method of track stiffness irregularity is analytically deduced, in which a novel solution of deformation of free beam is proposed. Then a high-speed vehicle–track–bridge dynamic interaction model is established based on the vehicle–track–bridge dynamic interaction theory. On this basis, the influence of track stiffness on the dynamic behaviours of the coupled system is investigated both in time domain and in frequency domain. Results show that the distribution of track stiffness in longitudinal direction indeed affects the vibrations of the system. More vibration details of system in full frequency bands can be revealed by considering track elasticity. The most sensitive indicator to different track types is the pitch acceleration of bogie. The wave amplitude caused by length of slab is very small, however its influence on vehicle vibrations is great, indicating that tiny track stiffness change caused by length of slab cannot be ignored in dynamic investigations.

轨道刚度不规则性在轨道表面表面上是看不见的，但在列车运行时会引起动力冲击和轨道变形。针对这个问题，本文研究了轨道刚度对高速车辆-轨道-桥梁动力系统动态行为的影响。首先，解析推导了轨道刚度不规则性的确定方法，提出了一种新的自由梁变形解法。然后基于车辆-轨道-桥梁动力相互作用理论建立了高速车辆-轨道-桥梁动力相互作用模型。在此基础上，从时域和频域研究了轨道刚度对耦合系统动力学行为的影响。结果表明，轨道刚度在纵向上的分布确实会影响系统的振动。通过考虑轨道弹性，可以揭示系统在全频段的更多振动细节。对不同轨道类型最敏感的指标是转向架的俯仰加速度。板条长度引起的波幅很小，但对车辆振动的影响很大，说明板条长度引起的轨道刚度的微小变化在动力研究中是不可忽视的。