我国高速铁路主要采用无砟轨道，作为新型轨道结构形式，国内外对其动力学研究较少，且大多只考虑系统的低频振动，远不能满足高速铁路的发展，因此进行无砟轨道-路基系统动力特性全频段研究迫在眉睫。本项目采用FE-SEA混合法建立车辆-无砟轨道-路基耦合系统动力模型，系统动力响应的低频、高频部分分别采用有限元法和统计能量法建模。同时考虑轨道中长波及短波随机不平顺激励，对高速列车通过时无砟轨道路基系统全频段动力响应特性进行定量分析，解决了计算效率和计算精度的矛盾。同时分析轨道不平顺、列车速度、轨道路基参数与系统动力特性的相关度，揭示影响轨道路基系统振动的关键参数，为合理选择轨道路基设计参数及减振措施提供理论依据，从而从源头上控制轨道路基系统振动。它的成功实施，不仅为高速铁路无砟轨道结构设计、养护维修等提供理论和技术指导，还将为大型综合系统振动预测提供新方法，因而项目具有较大科学技术意义及广阔的应用前景。

The ballastless track structure is mainly applied in China’s high-speed railway.As a new type of track structure, studies on its dynamics are comparatively rare at home and abroad. Besides, most of studies consider only the low-frequency vibration of the system, which is far from satisfying the development of high-speed railway. Therefore, an in-depth and systematic research for dynamics of ballastless track-subgrade coupled system at the wide frequency band is urgently needed. In this project, a dynamic model of vehicle-ballastless track-subgrade coupling system is established by the FE-SEA hybrid method. The low-frequency and high-frequency parts of the structure are modeled by the finite element method and the statistical energy method respectively.At the same time, the medium-long wave and short wave of the track random irregularities excitation are considered. The dynamic response characteristics of the ballastless track subgrade in the wide frequency band are analyzed quantitatively when a high-speed train is passing through it, which can better solve the contradiction between the computation efficiency and the calculation accuracy. Meanwhile, the correlations of track irregularity, train speed, track subgrade parameters and system dynamic characteristics are analyzed. The key parameters affecting the vibration of track subgrade structure are revealed, which provides theoretical basis for controlling the track structure vibration, managing irregularities, selecting appropriate values of track parameters for vibration-reduction measures. Its successful implementation provides not only the theoretical and technical guidance for the structural design and maintenance of high-speed railway ballastless track, but also a new method for the vibration prediction of large scale comprehensive system. Therefore, this project has great scientific and technological significance and broad application prospects.