Long-term deformation of railway tracks considering train-track interaction and non-linear resilient behaviour of aggregates - a 3D FEM implementation

Railway track designers and maintenance entities have long been pursuing for a robust and reliable method to predict the track's long-term behaviour. The complexity of this railway system, in terms of its changing structural and material behaviour throughout its life cycle, have hindered that quest. This paper presents a novel computer implementation focused on the estimation of the ballast and sub-ballast long-term deformation that provides a realistic reproduction of the actual behaviour of the structures because (i) it considers the three-dimensional aspect of the problem, (ii) incorporates accurate non-linear resilient material laws for the granular layers, (iii) uses a robust constitutive high-cycle strain accumulation model specifically devised for railway tracks that accounts for the three-dimensional stress conditions to determine both the volumetric and deviatoric permanent deformations and (iv) explicitly considers the dynamic train-track interaction. After calibration and validation with the results from an experimental case study comprising a physical model, a simulation scenario, considering different train types, is presented to demonstrate the potential of this approach. This implementation allows the construction of sufficiently extensive and elaborate representations of the railway track, allowing the study of geometrically complex cases and of the influence of many other aspects on its long-term behaviour.