Capacity of skirted foundations in sand-over-clay under combined V-H-M loading

The effect of the surface sand layer was profound for thicker sand layer of Ts/D > 0.2. Normalised failure envelopes were presented in v-h, v-m and h-m spaces. The FE results on the former two spaces showed unique trend, but not on the latter. New approximating expressions for describing the failure envelopes as a function of the sand layer thickness ratio, skirt length ratio and vertical load mobilisation level were proposed.