Soil-Geogrid Reinforcement Interaction by Pullout and Direct Shear Tests

Abstract Pullout and direct shear tests have been conducted to investigate the soil-reinforcement interaction behavior in pullout and direct shear mechanisms. An apparatus—discussed in this paper—has been developed that is capable of performing both pullout and direct shear tests. Displacement measurements to monitor dilatancy on the backfill soil during pullout tests are incorporated in the apparatus. Test results for the geogrid type of reinforcement embedded in dense granular soil are discussed. The devised testing program provides valuable information on the appropriate interaction models and parameters that will be employed in the design and analysis of reinforced soil structures. The dilatancy measured in the laboratory may also provide useful information on the increase of interface shear resistance when dilatancy is restrained under field conditions.