THREE-DIMENSIONAL BEARING CAPACITY ENVELOPES FOR A CIRCULAR FOOTING RESTING ON SAND OVER CLAY

The bearing capacity envelopes for a circular foundation are a fundamental problem in geotechnics. Bearing capacity envelopes for combined vertical, horizontal and/or moment loading are well-documented in the literature based on laboratory model tests and numerical analysis for the case of a footing resting on uniform sand or clay soils. Soils are, in reality, rarely homogeneous and often layered and in such situations it is important to consider the non-uniformity of the soil. This paper reports a suite of finite element analyses performed to examine the bearing capacity envelopes of circular footings resting on a soil profile comprising sand over clay and their evolution with the thickness of the sand layer under combined vertical and horizontal loading. The resulting envelopes are compared with those for uniform sand and clay stratigraphies and a framework for the evolution of the envelopes is established.