The development of high-speed train lines has increased during the last twenty years, leading to more demanding loads in railway infrastructures. For these reasons, the implementation of a numerical tool for the calculation of railway ballast behaviour has been found useful, as it will enables design optimization.
Regarding the numerical method, the DEM is considered effective and powerful for the calculation of engineering problems with granular and discontinuous materials. Due to the fact that railroad ballast layer consists of discrete aggregate particles, the DEM is considered suitable for the simulation of particulate ballast material. However, the computational cost of contact calculation between irregular particles is high and limits the calculation capability.
From the point of view of micro-scale analysis, it is essential to represent the exact geometry of the particle. On the other hand, if the interest lies in the behaviour of the granular material as a whole, the geometry is not a determining factor. Besides that, setting up a simulation of granular material taking care of the exact geometry of each particle will not be efficient.
Current work presents different geometrical approaches for the representition of ballast stones: spheric particles with rolling friction, sphere clusters, polyhedrons and superquadrics; showing their advantages and drawbacks.
Finally, some simulation results, using spheric particles and sphere clusters, are displayed in order to evaluate
the convenience or not of using more accurate and computational demanding geometries in each case
