Drag anchor behaviour in soft clay deposits: model investigation in transparent clay surrogate and analytical predictions

As the offshore energy industry begins to develop wind farms in areas of deeper water, the use of traditional foundations such as shallow foundation and driven hollow steel tube piles becomes uneconomical. The deployment of floating turbines and continued development of novel/efficient anchoring systems for these structures will be an important factor in the continued growth of the sector. This paper presents an investigation carried out as part of a proof-of-concept for a novel “bi-wing anchor”. This design will allow a plate anchor to be dropped through the water column and then penetrate the seabed under its own weight. The anchor will then be dragged causing it to embed further into the seabed and provide a greater holding capacity. This paper focuses on experimental as well as analysis of the drag embedment behaviour during the installation and pullout phases. The physical modelling investigations were carried out in a transparent clay-surrogate which enabled observation of the anchor’s orientation during installation. The predictions using analytical modelling showed good agreement with the observed behaviour at varying embedment ratios.