Bearing Capacity of Square Footings on Sand Reinforced with Dissimilar Geogrid Layers

This paper aims to investigate the likely effects of geogrid reinforcement configuration on footings bearing capacity. Using geogrids reinforcement layers with certain total areas in various uniform and non-uniform arrangements, the bearing capacities of footing models on reinforced sand beds were determined and compared. The first arrangement was the conventional uniform layout in which 3 geogrid layers of equal dimensions were considered. In the second group the same amount of geogrids were used in a trapezoidal profile in which smaller size geogrid were placed at upper layers and the geogrid dimensions increased with embedment depth. The third group consisted of arrangements in which the same amount of geogrids were used in an inverse trapezoidal layout i.e. the layer sizes decreased with embedment depth. The effect of soil density on the footing performance was also investigated. The tests results indicated that in all soil densities, the greatest bearing capacities were obtained for the sand beds reinforced with inverse trapezoidal reinforcement layouts while the least bearing capacities were determined for trapezoidal arrangements.The improvement ratio of bearing capacity due to geogrid reinforcement varied from 1.8 to 5.35 depending on the reinforcement layout and the sand bed density.