Discrete element analysis of geogrid-stabilized ballasted tracks under high-speed train moving loads

Abstract

The violent vibration and excessive settlement of trackbeds under high-speed train moving loads are the main problems of ballasted tracks encountered in practice, which limits the rise of operation speed for ballasted railways. To date, the possibility of extending the widely used geogrid in conventional ballasted railways to high-speed railways has not been adequately validated. The stabilization mechanism of geogrids under high-speed train moving loads remains unclear. Herein, a ballasted track DEM model containing five sleepers that reproduced high-speed train moving loads was developed through EDEM software and validated by full-scale model tests. Both cases of ballasted tracks with and without the geogrid were examined. The results showed that the geogrid significantly decreased the total and differential settlement of the ballasted track. After geogrid installation, the coordination number of ballast particles was increased, and the contact forces among ballast particles were reduced, which potentially lowered the ballast breakage. The geogrid effectively constrained the displacement and rotation of ballast particles. The reduced migration of ballast particles led to a smaller and more uniform volumetric strain field of the ballasted trackbed. By investigating the working mechanism of the geogrid, it was shown that the penetration of the ballast particles into the geogrid aperture induced the expansion of the geogrid aperture, and therefore, the lateral force from the geogrid ribs limited the movement of the ballast particles.