Investigating the influence of ballast resilient properties variability on vehicle-track interaction

Abstract

Railway tracks consist of various components and experience different support conditions along the longitudinal axis. The vertical stiffness of railway tracks varies significantly in space and time, and the resilient properties of the supporting layers are also affected by several factors. While many studies propose complex behaviour models for geomaterials to represent these variations, very little work has been done to account for the random variability of these properties over space and time. In this study, 133-m long 3D train-track numerical models were used to investigate different scenarios with stochastic spatial variability in the ballast layer. The used finite element method program – Pegasus – considered the dynamic interaction between the vehicle and the track-substructure system to analyse the influence of the variability of resilient properties of the ballast layer on the structural response in the time-domain. Parametric studies are presented studying the influence of speed on the variation of resilient properties in the ballast layer, and the attenuation of resonance effects was also investigated by evaluating the differences between models with and without the variability of these properties. The simulations showed that the variability of resilient properties is expected to have little influence on the overall response of the vehicle-track-soil system. However, the analysis of mean and deviatoric stresses suggested that it may have some relevance in terms of the local stress analysis in the ballast layer.