Model-Based Investigation of the Dynamic Behaviour of Railway Ballast

Abstract

The representation of ballast in conventional track models is unsatisfactory, since still important physical phenomena inside the ballast layer are not understood. Therefore, in this paper an alternative theoretical approach, the Molecular Dynamics method (MD method) as a powerful tool for the investigation of granular material, is investigated. In contrast to a continuum description, in the corresponding 2D-model each single stone of the ballast can be taken into account. In the frame of a numerical time-step integration, the contact forces are calculated from the overlap area of the particle geometries.

The paper includes information about the sensitivity of the model behaviour on initial conditions and contact law parameters. Furthermore, the contact network, the quasi-static stiffness of the ballast layer and its long-term behaviour are addressed. Particular emphasis is put on the description of current difficulties and challenges in applying the MD method.