国内外高速铁路运营实践表明，轨道和路基病害集中于不同轨道基础间的过渡段，即使在保证轨面平顺条件下，过渡段轨道劣化速率及路基病害发生率仍明显高于一般路基段或桥梁段。产生这种现象的一个重要物理原因在于轮轨接触产生的弹性波在过渡段中传播发生渡越辐射现象。本课题将从波动和能量的角度给出高速铁路过渡段刚度变化引起弹性波渡越辐射现象的数学表达。建立过渡段复杂多界面非均匀弹性介质波场计算模型，在亚临界速度移动荷载和界面耦合的条件下，通过本征场和自由场求解波动方程，得到空间-频率域位移场解；通过位移场推导渡越辐射能量流表达式；分析列车运行速度、过渡段刚度差异和弹性波入射角度对渡越辐射能量流的影响规律；将此影响量化为过渡段车辆-轨道系统外力向量修正，分析渡越辐射对过渡段列车运行平稳性影响，评价既有过渡段设计能否满足系统长期动力稳定要求，以期为新型高速铁路过渡段设计提供理论依据。

The operation practices of the high-speed railway in China and foreign countries indicated that the defects of the track and the subgrade occurred most frequently in transition zones between different track foundation configurations. Even if the track geometry irregularity can be well controlled, the degradation rate of the track and the subgrade in transition zones is obviously higher than that of the normal subgrade or normal bridge zones. A most important physical reason of this phenomenon is the transition radiation of the elastic wave, which is induced by the wheel-rail contact of the high speed trains, due to the track and subgrade inhomogeneity. The mathematical expression of the transition radiation energy of the elastic wave in high-speed railway transition zones due to subgrade stiffness and geometry inhomogeneity will be given in this project. The mathematical model of the heterogeneous elastic media with multi complex interfaces will be established. Based on the assumptions that the load velocity is taken sub-critical and waves are coupled in the interfaces, the solution of the model in the space-frequency domain will be obtained both in the eigen field and the free field. The transition radiation energy flux expression can be derived by the displacement field solution. The influence of the train speed, the stiffness contrast and the incident angle of the elastic waves on the transition radiation energy flux will be studied. Based on these influences, the external force vector of the vehicle-track system can be derived. With the update of the external force vector, the effect of the transition radiation on the vehicle running stability can be investigated. As result the dynamic transition performance of the existed transition zone configuration can be evaluated. The research achievement of this project can be used as the design theoretical basis of the new transition zone configuration.