BEARING CAPASITY AND SETTLEMENT OF FOOTING RESTING ON CONFINED LOOSE SILTY SANDS

Abstract

An experimental study on the influence of cell confinement on the bearing capacity and settlement of circular footing on silty sand was carried out. Laboratory experiments on clean sand and sand containing silt up to 25% were performed. Model cells with different diameters and heights have been used to confine the silty sand. The effect of the cell diameter, cell height and fines on bearing capacity and settlement were investigated with the help of an experimental programme using circular footing having a diameter of 0.15m. Initially, the response of a footing without confinement was determined and then compared with that of footing with confinement. The results indicate that the bearing capacity of circular footing decreases on the addition of fines and can be appreciably increased by soil confinement. The results also indicate that the settlement of circular footing can be appreciably decreased by soil confinement. It was interpreted that such confinement provides lateral displacement of soil underneath the footing. It leads to a significant improvement in the response of the footing. The cell–soil footing behaves as one unit for small cell diameters, while this pattern was no longer observed with large diameter cells. The recommended cell diameters that give the maximum ultimate bearing capacity improvement and less settlement are presented and discussed.