Large-scale model tests on performance of shallow circular footings on geogrid-reinforced sand

In this paper, plate loading tests were conducted to investigate the load and deformation behaviors of the geogrid-reinforced sand foundation under circular footing with a diameter of 0.4 m. The parameters examined include the reinforcement tensile stiffness, the number of reinforcement layers, and the spacing between reinforcement layers. The vertical stresses in the soil, surface deformations and strains in geogrids were monitored during loading. Test results show that the efficiency of geogrids in improving soil's bearing capacity is closely related to footing settlement. The larger the settlement, the better the reinforcing effect as s/D > 3%, where s and D is the settlement and diameter of circular footing, respectively. The stiffness, spacing and number of reinforcements significantly influence the stress distribution effect of geogrid-reinforced zone. The effective influencing depth and diameter of the stress distribution effect are approximately 3D and 1.4D, respectively. Generally, the maximum tensile strain in the geogrids occurs around the footing center, while the maximum compressive strain is located at approximately 1D from the center. The maximum tensile strain is greater affected by the vertical spacing, whereas the number of reinforcement layers has a significant effect on the maximum compressive strain.