THREE-DIMENSIONAL ANALYSIS OF BEARING CAPACITY OF SQUARE FOOTINGS ON CONVEX SLOPES BY FINITE ELEMENT METHOD

Soil slopes are sometimes curved in plan rather than being straight. This curvature, especially when it is convex, decreases the bearing capacity of the slope. Finite element method has been used here in this research to investigate the reducing effect of curvature on bearing capacity of a slope. Failure of soil has been assumed to be according to Mohr-Coulomb criteria; but the flow rule of the soil has been considered unassociated. Both cohesive and frictional soils have been used in these investigations to observe the effect of soil type on the problem. Investigations consist of four types of cohesive soils having different strengths and four types of frictional soils having different friction angles. The finite element model consisted of a square footing adjacent to a slope that is convex in plan. Besides changing the curvature; the slope angle and the footing to slope distance have also been varied to see their effects as well. Based on the results of these investigations it has been concluded that convex curvature generally reduces the bearing capacity and this effect is more pronounced in steeper slopes. While this reduction is limited to 7% in case of cohesive soils it can be as high as 15% in case of frictional soils. Therefore this effect should be considered in design of slopes that are convex in plan.