Stress and permanent deformation amplification factors in subgrade induced by dynamic mechanisms in track structures

Abstract

In this paper, the performance of different railway structures – ballasted and two types of slab tracks (Rheda system and a ballastless track only constituted by the concrete slab) – is evaluated in terms of stresses and permanent deformations through the selection of some important parameters: wavelength of the unevenness profile, train’s speed, subgrade’s characteristics and spatial variability of the track unevenness profile. The elastodynamic response of 60 case studies is computed through a 2.5D model FEM-PML and the long-term behaviour is assessed by the implementation of a permanent deformation model. The obtained results are analysed through innovative stress and permanent deformation amplification factors in the subgrade layer. This study concludes that the train’s speed and the mechanical properties of the subgrade are the factors that most affect the long-term performance of the subgrade of railway structures, which must be considered for further optimization of the rail track structures.