Effects of transverse members on geogrid pullout behavior considering rigid and flexible top boundaries

Geogrid pullout tests have been regarded as the most direct and effective way to describe the interfacial behavior between geogrid and soil. To investigate the coupled effects of geogrid transverse members and top-loading boundaries on the geogrid-soil interaction, numerical simulations of geogrid pullout tests using the Discrete Element Method (DEM) were carried out in this study. The rigid top boundary was simulated by a rigid wall, while the flexible top boundary was modeled with a string of bonded particles that could rotate and move up and down freely. The coupled effects of geogrid transverse members and top boundary conditions on the geogrid-soil interaction under pullout loads were visualized not only by the force distributions along the geogrids and in the specimens but also by the displacements of soil particles and geogrids. Additionally, the quantitative geogrid force and strain distributions along the geogrids, the lateral force distributions on the front walls, and the vertical displacements of top boundaries also showed the influence of transverse members on the geogrid pullout behavior considering the rigid and flexible top boundaries. The DEM investigation results of this study may provide helpful guidelines for regulating the geogrid pullout test apparatus and methods.