Visualisation of mechanisms governing suction bucket installation in dense sand

Suction buckets are an increasingly considered foundation option for offshore wind turbines. The required suction can be predicted well using existing methods, though there remains uncertainty around some input parameters, because the effects of suction installation on the soil state are not understood in detail. This paper visualises the response through particle image velocimetry measurements of both initial self-weight penetration and following suction-assisted installation in dense sand, achieved in a centrifuge environment.
Changes in the deformation mechanisms governing the installation process and in the soil properties are revealed, significantly advancing current knowledge. The findings have an impact on the understanding of the formation of internal plug heave – the cause of premature refusal – and the prediction of the installation response. Revealing changes in void ratio and permeability also present implications on the accumulated displacements under the metocean cyclic loading, which may conflict with serviceability requirements.