Behavior of circular footing resting on laterally confined granular reinforced soil

Three dimensional physical laboratory models were examined to investigate the influence of soil confinement on circular footing behavior resting on granular soil. A total of 23 model footing tests were performed. Nine hollow cylinders with various heights and diameters were installed around the footing model for soil confinement purpose. Square geogrid layers were placed at different depths beneath the bottom edge of the cylinder. Different parameters such as height, diameter, and depth of the cylinder were studied. Moreover, number, width, and position of the geogrid layers were, also, investigated. The response of a non-confined footing model was set as reference for comparison purpose. The results showed enhancement in the bearing capacity of the soil as well as a reduction in its settlement in all used configurations compared with the reference case. It is, however, observed that on increasing the number of geogrid layers more than one layer had a small significant effect on the footing behavior. Moreover, placing geogrid layers underneath the cylinders improves the bearing capacity up to 7.5 times that of the non-confined case. Footing with cylinder of a diameter nearly equal to the footing diameter behaves as one unit like a deep foundation. This behavior pattern was no longer observed with large cylinder diameter and small height. Finally, the study ends up with recommendations for selection of cylinder dimensions to maximize the bearing capacity. The benefits of using geogrid layers were also highlighted.