研究目的:无砟轨道结构的弹性主要来源于扣件系统，在高速铁路无砟轨道施工或维修过程中，扣件系统可能出现安装不当或新旧轨下垫板不合理过渡的情况，从而在相邻的扣件间形成较大的刚度差或称刚度突变，静态条件下难以发现，但可能对高速行车的平稳性和安全性产生不利的影响。本文应用轮轨系统动力学理论和ANSYS/LS-DYNA有限元软件，建立了车辆-无砟轨道-路基系统垂向耦合振动模型，根据扣件刚度实际检测的范围，考虑不同的扣件刚度突变工况，计算分析扣件刚度突变对高速车辆及轨道动力特性的影响。研究结论:经过计算分析表明:(1)当扣件刚度局部发生突变时，车体加速度最大值和最小值基本不变，即扣件刚度突变对行车平稳性的影响不大；(2)扣件刚度突变对轮重减载率即行车安全性的影响明显，尤其是列车速度超过300 km/h时，扣件刚度突变直接导致轮重减载率超标；(3)该研究成果可为高速铁路无砟轨道扣件刚度在施工或维修中加强检测、建立严格的控制标准提供理论依据。

Research purposes:The elasticity for the ballastless track structure is mainly provided by the fastening system. During the construction and maintenance of ballastless track on high-speed railway, the incorrect installation and the unreasonable transition between the old and new rail-pads may occur to the fasteners, which will cause a stiffness mutation for the fasteners. Even though this problem can hardly be found under the static condition, it can have a great effect on the stability and safety for the high-speed vehicle operation. Here different conditions for the fastener stiffness mutation are considered, according to the actually measured data. And the influence of fastener stiffness mutation on the dynamic performance of high-speed vehicle and track is calculated and analyzed by using the vertically coupled vehicle-ballastless track-subgrade vibration spatial model and the finite element software ANSYS/LS-DYNA.Research conclusions:The calculation and analysis results show that: (1)When there is a local mutation for the stiffness of fasteners, the maximum and minimum of vehicle acceleration basically keep the same. That is to say, the fastener stiffness mutation has few influence on the stability of vehicle operation. (2) The fastener stiffness mutation has much obvious effect on the wheel load reduction rate, which is related to the safety of vehicle operation. Further, when the train speed is larger than 300 km/h, the fastener stiffness mutation will directly cause the wheel load reduction rate to exceed the standard. (3) This research results can be used to provide a theoretical basis for monitoring the fastener stiffness in construction or repairing and establishing the strict control standards in high-speed railway.