In a railway track, the sleeper’s responses on a non-homogeneous foundation have been investigated by researchers focusing on the foundation behavior along the rails. However, the foundation can also vary along the sleeper length, particularly when the track is newly tamped. The foundation at the sleeper center is often weaker than those under the rails and this non-homogeneity directly affects the sleeper responses. This paper presents a new model to calculate the influence of such foundations on the dynamic responses of the railway sleepers. This model is developed by combining a finite element model for the sleepers and foundation and a model of periodically supported beams subjected to moving loads for the rails. In this paper, the foundation contains three parts with different mechanical behaviors. The sleeper’s responses can be calculated by transforming the finite-element dynamic stiffness matrix to the one considering the boundary conditions and the relation between the rail seat forces and rail displacements governed by the beam model. This method reduces all the degrees of freedom of the railway track to its one period which gives a substantial reduction in computational time. The numerical applications show that the more homogeneous (so-called consolidated) the foundation is, the larger the sleeper strain is at its center. This result shows the potential application of the sleeper responses to estimating the consolidation level of the foundation.

中文翻译：

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非均质基础对轨枕动力响应的影响

在铁路轨道中，研究人员已经研究了轨枕对非均质地基的响应，重点关注铁轨沿线的地基行为。然而，基础也可以沿轨枕长度变化，特别是在新夯实轨道时。轨枕中心的基础通常比钢轨下的基础更薄弱，这种不均匀性直接影响了轨枕的响应。本文提出了一种新模型来计算此类基础对铁路轨枕动力响应的影响。该模型是通过将轨枕和基础的有限元模型与承受轨道移动载荷的周期性支撑梁模型相结合而开发的。在本文中，地基包含三个具有不同力学行为的部分。可以通过将有限元动态刚度矩阵转换为考虑边界条件以及由梁模型控制的轨道座力和轨道位移之间的关系来计算轨枕的响应。这种方法将铁路轨道的所有自由度降低到一个周期，从而大大减少了计算时间。数值应用表明，基础越均匀（所谓的固结），其中心的轨枕应变越大。该结果显示了轨枕响应在估计基础固结水平方面的潜在应用。