The Performance of Strip Footing Resting on Geogrid-Reinforced Dune Sand

Laboratory model tests were carried out to study the behavior of strip footing resting on a geogrids-reinforced dune sand. The tests were performed on a rigid steel tank having glass side with inner dimensions of 1 m by 0.64 m by 0.23 m. Footings were placed at different depths from the surface of sand. Geogrids were placed at different depths below the footing starting at 0.25B to 1.25B. The sand was placed in the tank using raining method. The use of geogrids improved the bearing capacity of strip footings by a factor of up to 4 times. The improvement depends on depth of the footing, the depth of the geogrids below the footing and the number of the geogrids layers. For two layers of geogrids the highest improvement is when the depth of first reinforcement below the footing is between 0.25 to 0.5B, the spacing (h) is between 0.25 to 0.5B and the overall depth of the reinforcements (d_r) is about 0.5 to 0.75B. The geogrids modified the load-settlement curve for the footing by increasing the strains at failure to up to three times that of unreinforced sand. This means with geogrids the footing will undergo more elastic settlements before failure.