Shape Effects on the Undrained Uplift Capacity of Skirted Suction Foundations in Clay

Abstract

Skirted suction foundations are an attractive solution for floating offshore wind turbines that are subject to uplift due to overturning or buoyancy loading. Current industry design guidelines give conservative collapse loads for offshore shallow foundation systems, particularly due to neglecting the beneficial effect of suction developed within the soil plug during rapid uplift. The behavior of skirted rectangular and circular footings subjected to uplift loading has been studied using centrifuge model tests and upper bound plastic limit analyses. Results demonstrate that the shape effects on the uplift capacity factor are not significant when the circular and rectangular footings both obey reverse end bearing failure mechanism. Simple predictive methods based on existing bearing capacity theory are provided.