Simplifying transformations for the analysis of shallow foundations on sand

Abstract

Prediction of the ultimate load capacity of shallow sand-supported foundations is a fundamental offshore engineering problem. The paper demonstrates how the complete (V,H,M) failure envelope of such foundations, represented by a system of parabolas and rotated ellipses, can be transformed into a single unit circle by referring the applied loads to an origin located below the foundation centerline. The conjugate transformation applied to the corresponding displacements generates a symmetry amongst them, for symmetrical load paths, not otherwise apparent. Extensive, model-scale, experimental data is presented which provides convincing support for the unit circle failure envelope.