EXPERIMENTAL BEHAVIOR OF POLYMERIC GEOGRIDS IN PULLOUT

The increasing use of polymeric geogrids in reinforced soil walls and steep slopes warrants special attention to all details including their anchorage behavior. Because of the open structural nature of geogrids, their performance is different from other sheet-like reinforcing materials such as metallic strips and geotextiles. They derive their anchorage capacity through both friction and bearing resistances. This paper focuses on the structural behavior of geogrids under a pullout loading condition. An experimental investigation is conducted using three different geogrids tested at three different lengths. The load-displacement response at different locations along the geogrid is monitored during pullout. The experimental results are compared with predictions using a previously published finite-element model simulating soil-geogrid interaction and taking into account the deformation of the geogrid structure. Tension in the geogrid, as well as friction and bearing components of resistance, are presented in relation to geogrid length, pullout load magnitude, and distance from the clamped end of the geogrid. Factors such as the load-extension behavior of ribs in the pullout load direction and the flexibility of ribs in the perpendicular direction as well as their ability to transfer the load through the rib junctions are shown to greatly influence the overall behavior. The results emphasize the fact that the success of a geogrid in fulfilling its anchorage role is directly related to its structural composition and material specific characteristics.