Two-dimensional DEM analysis of behavior of geogrid-reinforced uniform granular bases under a vertical cyclic load

Geogrid reinforcement of a base course improves its performance in unpaved and paved roads under traffic loading. The interaction of the geogrid with the base aggregate is critical to the improved performance but not fully understood. The two-dimensional numerical method, discrete element method, was used in this study to investigate this interaction under a vertical cyclic load. The geogrid reinforcement was placed at the bottom or the mid-depth of the base course. A vertically loaded wheel was applied cyclically on top of the base course. This study investigated the effects of the cyclic load and the geogrid placement depth on the performance of the geogrid-reinforced base as compared with the unreinforced base. Under a heavier load, the geogrid placed at the mid-depth of the base performed better than that placed at the bottom of the base. The numerical results show that geogrid helped widen the distribution of contact force chains and mobilized its tensile strength. The geogrid increased the load capacity and elastic deformation and reduced the plastic deformation of the base course by providing lateral and vertical confinements.