Geomaterials exhibit elastoplastic behaviour during dynamic and repeated loading conditions. These loads are induced by the passage of a train or vehicle which then generates recoverable (resilient) deformation and/or permanent (plastic) deformation. Modelling this behaviour is still a challenge for geotechnical engineers as it implies the understanding of the complex deformation mechanism and application of advanced constitutive models. This paper reviews on the major causes of permanent deformation and the factors that influence the long-term performance of materials. It will also present the fundamental concepts of permanent deformation as well as the models and approaches used to characterise this behaviour, including: elastoplastic models, shakedown theory and mechanistic-empirical permanent deformation models. This paper will focus on the mechanistic-empirical approach and highlight the evolution of the models, and the main similarities and differences between them. A comparison between several empirical models as well as the materials used to develop the models is also discussed. These materials are compared by considering the reference conditions on the type of material and its physical state. This approach allows for an understanding of which properties can influence the performance of railway subgrade and pavement structures, as well as the main variables used to characterise this particular behaviour. An innovative ranking of geomaterials that relate to the expected permanent deformation and classification (UIC and ASTM) of soil is also discussed because it can be used as an important tool for the design process.

在动态和反复加载条件下，土工材料表现出弹塑性行为。这些载荷是由火车或车辆通过引起的，然后火车或车辆产生可恢复的（弹性）变形和/或永久的（塑性）变形。对这种行为进行建模对于岩土工程师仍然是一个挑战，因为它意味着对复杂变形机制的理解和高级本构模型的应用。本文回顾了永久变形的主要原因以及影响材料长期性能的因素。它还将介绍永久变形的基本概念以及用于表征这种行为的模型和方法，包括：弹塑性模型，振动理论和力学经验永久变形模型。本文将重点关注机械-经验方法，并重点介绍模型的演变以及它们之间的主要异同。还讨论了几种经验模型之间的比较以及用于开发模型的材料。通过考虑有关材料类型及其物理状态的参考条件来比较这些材料。通过这种方法，可以了解哪些属性会影响铁路路基和路面结构的性能，以及用于表征这种特殊行为的主要变量。还讨论了与预期的土壤永久变形和分类（UIC和ASTM）有关的土工材料的创新排名，因为它可以用作设计过程的重要工具。