Ballasted Track Maintenance Modelling Using DEM

Abstract

The ballast layer is a crucial component of railway tracks and it is hence essential to maintain it using adequate processes like tamping and stabilization. These will ensure that the density of the ballast layer is high enough to avoid shearing and settlement of the track under traffic. Ballasted tracks settle unevenly under the passage of trains. These geometrical defects are corrected by tamping which consists of lifting individually the sleepers and compacting the ballast underneath using vibrating tines. After tamping, the ballast layer is not homogeneous in terms of density along the track and requires stabilization before being commercially operational. This stabilization is performed either by regular trains at lower speeds for a given period hindering commercial operations, dynamic stabilization, or crib compaction. All these processes rely on vibrating the ballast layer using different approaches and have mainly been based on empirical observations. This paper describes an analysis of these ballasted track maintenance processes and their optimization using the discrete element numerical approach. This approach considers a granular material as an assembly of objects interacting through a specific contact law. In the present study, the code called LMGC90 has been used. The study includes a comparison of the processes in terms of ability to compact the ballast layer and lateral mechanical resistance of the track and their optimization. The final purpose of the project is to be able to specify optimal functioning parameters for all these processes.