Centrifuge tests exploring the cyclic performance of suction bucket foundations in cohesionless soils

Abstract

An alternate to monopiles to support offshore wind turbines is the use of jacket structures founded on suction buckets. These foundations have been successfully deployed in recent developments and have proven to be a viable foundation concept due to their relatively fast and low-noise installation, as well as their general applicability for a wide range of soil-conditions and suitability in deeper waters. However, the behaviour of bucket foundations subject to both short- and long-term uplift loading in coarse grained soil remains an area of ongoing research. For the centrifuge testing in this project, offshore soil was provided from an Asian site – and the combination of silt size particles, water pore fluid and faster loading rates was used to replicate the drainage conditions during the loading of a full-scale bucket foundation in sand. Initial self-weight penetration of the skirts was followed by suction installation, with in-place testing then undertaken to explore both monotonic and cyclic performance. This paper presents results from the pilot testing, including the foundation response to cyclic (storm) loading applied symmetrically around an average uplift load.