A complete three-dimensional failure envelope for shallow footings on sand

This paper considers the possibility of constructing a three- dimensional failure envelope for a shallow sand-supported footing. Earlier two- dimensional work is outlined and data taken from a number of sources to produce best-fit eliptical cross-sections. Equations are then presented for a complete three-dimensional failure envelope, comprising a system of inclined elipses and intersecting parabolas. The equations are normalised and compared with test data. It is suggested that the three-dimensional surface will provide a simpler method for predicting failure loads and the effect of specific combinations.