Experimental and Numerical Studies of Circular Footing Resting on Confined Granular Subgrade Adjacent to Slope

Abstract

Many situations exist where foundations must be constructed on or near slopes. As a result, the foundation’s bearing capacity is reduced, and the slope might collapse. This paper presents the results of laboratory and numerical model tests on the influence of soil confinement on the behavior of a model footing adjacent to slopes. Confining cylinders with different heights, each set back some distance from the slope crest, were adopted. The ultimate bearing capacity of a circular footing supported on a confined sand bed adjacent to a slope was studied. The studied parameters include the cell-embedment depth, slope angle, and subgrade density. The results indicate that the bearing load capacities of circular footings at any edge distance from the slope crest can be appreciably increased by soil confinement. The slope effect on the ultimate bearing capacity can be neglected when the cell-footing system is placed at setback distance with cell-embedment depth around two times the cell diameter. When the cell-footing system is placed directly on a steep slope crest, the improvement in the bearing capacity reached 4, 2.2, and 1.9 times the footing with subgrade relative densities of 80, 55, and 35%, respectively. The numerical analysis helped to explain the deformation behavior of cell-footing soil systems adjacent to a slope. It provides a realistic failure mechanism of the new system and illustrates how the cell can protect the slope from collapse by decreasing slope deformation.