The influence of vertical effective stress and geogrid length on interface behavior under pullout conditions

Geogrids are one of the most common types of geosynthetic used for soil reinforcement. In particular, the use of geosynthetics has unique advantages over other soil strengthening techniques, because of technical, economic, and sustainability reasons. The redistribution of internal stresses within reinforced soil mass and its deformations depends on soil shear strength, reinforcement tensile strength and stiffness, and on interface stress mechanisms between soil and reinforcement. The results of pullout tests carried out on two extensible geogrids embedded in a compacted granular soil, in terms of peak pullout resistance at soil-geosynthetic interface, are analyzed. Some considerations about deformation behavior analysis are also reported. The equipment incorporates two sleeves near the slot at the front wall of the pullout box to avoid front wall effects, as recommended by researchers. The pullout apparatus is capable producing the confined failure of a geosynthetic specimen by using an internal clamp placed inside the soil beyond the sleeves