Influence of rigid and flexible top boundaries on geogrid pullout behavior using DEM

Abstract

In geogrid pullout tests, either a rigid or a flexible top boundary is used to determine the ultimate pullout resistance of geogrids. This study aims to investigate the influence of rigid and flexible top boundaries on geogrid pullout behavior using discrete element modeling. In the numerical modeling, each top boundary was simulated with a string of bonded particles. The rotations of the bonded particles were fixed for the rigid top boundary, while the bonded particles could rotate freely for the flexible top boundary. The influence of rigid and flexible top boundaries on geogrid pullout behavior was discussed by the pullout force–clamp displacement relations as well as the tensile force distributions along the geogrid and the contact force distributions in the specimen. Although slight differences were observed in the comparative discrete element modeling, the DEM simulation results still show that the top boundaries do not influence the mobilization of pullout resistance at small clamp displacements. Hence, it is suggested that both rigid and flexible top boundaries can be used to investigate the geogrid pullout behavior at small clamp displacements.