Discrete Element Modelling of Railway Ballast Problems: an Overview

Ballast made up of discrete granular particles of rock is a principal component of railway tracks. This review paper focuses on using Discrete Element Modelling (DEM) for modelling ballast in railway track systems. It provides a comprehensive overview of past, present, and future challenges and developments in this area of research. The review discusses the various analysis principles used in DEM, including contact mechanics, representation of particle geometry, breakage and abrasion, and inclusions such as geosynthetics, fibres and rubber elements. It also describes the numerical interfaces between DEM and other analysis types (e.g., finite element modelling, multi-body dynamic, computational fluid dynamics, smoothed-particle hydrodynamics) that have been implemented to simulate ballasted railway-related problems, such as the subgrade modelled as a continuum and sleepers, and fluid and mechanical interactions, such as water washout, ballast flight, and track maintenance machines. Finally, the review outlines future challenges and directions for numerical analyses of ballasted railways.