Advancements in geo-inclusions for ballasted track: Constitutive modelling and numerical analysis

This paper reviewed some salient features evolving through mathematical and numerical modelling of ballasted track components incorporating recycled rubber products. Firstly, a constitutive model based on the bounding surface concept was introduced to simulate the shear stress-strain response of waste mixtures (i.e., recycled rubber crumbs, coal wash, and steel furnace slag) used for the capping layer placed below the ballast medium, whereby the energy absorbing property resulting from the inclusion of different amounts of rubber has been captured. Subsequently, key research findings concerning the inclusion of recycled rubber mats on ballasted tracks for re-duced particle degradation under cyclic loading were examined and discussed. Discrete element modelling (DEM) coupled with Finite element modelling (FEM) to micro-mechanically characterise ballast behaviour with and without rubber mats offers invaluable insight into real-life track opera-tions. In particular, this coupled DEM-FEM model facilitates the exploration of micromechanical aspects of particle breakage, contact force distributions within the granular assembly, and the ori-entation of contacts during cyclic loading