本文建立了车轮一轨道一道碴为一体的有限元动力计算模型。在这个计算模型中,钢轨 被离散成平面梁单元，道碴是作为附加自由度包含在梁单元中。这种处理方法,使得作为附加自由 度的道碴可在单元水平上进行刚度、阻尼和质量的迭加，从而极大地降低了总刚度矩阵的带宽。作 为实际应用的例子 文章对不同道碴厚度条件下，轨道结构的动力响应进行了分析,获得了一些初 步结论。

A dynamic finite element model for system of wheel—rail—ballast is proposed in the paper. In this computational model, the rails are discretized into plane beam elements in which the ballast is considered as additional degree of freedom. This treatment makes it pos?sible for us to assemble the stiffness，damp and mass of the ballast on the element level， which greatly reduces the band width of the total stiffness matrix. As an application exam?ple t the dynamic responses of rail track structure with different ballast thickness are analyzed and some preliminary conclusions are obtained.