This paper aims at showing that the reversible behavior of track ballast can be reasonably modeled by a homogeneous elastic layer in the computation of the reversible dynamic response of railway structures subjected to moving train loads. To accomplish this, 2D simulations by means of the discrete element method (DEM) and triaxial tests were carried out. Importantly, these two approaches were performed placing a soft support under the granular specimen. A small number of loading cycles has been considered in both approaches since the long-term settlement of the ballast layer is not the focus of this study, unlike most of the existing research on this topic. In the DEM part, the transfer of the mechanical loads applied to the sample through force chains in the granular medium has been illustrated and discussed based on the numerical responses obtained. In addition, the analysis of the overall response of the grain samples using a homogenized constitutive law shows that the reversible behavior of a ballast layer can be modeled by a continuum approach. However, investigating the effect of the subbase stiffness on the mechanical response of the ballast layer indicates that the homogenized behavior is not intrinsic but depends on the sublayer. These results were confirmed by triaxial tests performed in the laboratory on samples of crushed stones resting on an elastomer mat with different values of the stiffness. Finally, the results from the DEM simulations and the triaxial tests attest that the reversible response of railways can be computed using an elastic layer for the ballast bed provided that an appropriate choice for its apparent modulus is made. The approach that consists of deducing a reversible homogenized behavior of track ballast based on DEM simulations and/or triaxial tests taking into account the support layer looks promising. In future research, more realistic DEM simulations could be envisaged to develop more accurate constitutive laws that could integrate nonlinear and/or anisotropic aspects.

本文旨在表明，在计算运动荷载作用下的铁路结构可逆动力响应时，均质弹性层可以合理地模拟轨道道ball的可逆行为。为此，通过离散元素方法（DEM）和三轴测试进行了2D模拟。重要的是，执行了这两种方法，将软载体放置在颗粒样本下。两种方法都考虑了少量的加载周期，因为压载层的长期沉降不是本研究的重点，这与大多数有关该主题的现有研究不同。在DEM部分，基于所获得的数值响应，已经说明并讨论了通过颗粒介质中的力链施加到样品上的机械载荷的传递。此外，使用均化本构定律对谷物样品的整体响应进行分析，结果表明，可以通过连续方法对压载层的可逆行为进行建模。但是，研究基层刚度对道ast层机械响应的影响表明，均质化行为不是固有的，而是取决于基层。这些结果通过在实验室对放置在具有不同刚度值的弹性体垫上的碎石样品进行的三轴测试得到了证实。最后，从DEM模拟和三轴测试的结果证明，铁路的可逆反应可以使用用于提供对于它的表观弹性模量的适当选择是由道床的弹性层来计算。该方法由基于DEM模拟和/或三轴测试（考虑到支撑层）来推导出道ball的可逆均质行为组成，这看起来很有希望。在未来的研究中，可以设想出更现实的DEM模拟，以开发出可以整合非线性和/或各向异性方面的更准确的本构定律。该方法包括基于DEM模拟和/或考虑支撑层的三轴试验来推导出道ball的可逆均质行为，这种方法看起来很有希望。在未来的研究中，可以设想出更现实的DEM模拟，以开发出可以整合非线性和/或各向异性方面的更准确的本构定律。该方法由基于DEM模拟和/或三轴测试（考虑到支撑层）来推导出道ball的可逆均质行为组成，这看起来很有希望。在未来的研究中，可以设想出更现实的DEM模拟，以开发出可以整合非线性和/或各向异性方面的更准确的本构定律。