ABSTRACT

This Grant Opportunities for Academic Liaison with Industry (GOALI) project will support a research team to develop models for the loading placed on multiline ring anchors subjected to wind, waves and other forces. A Multiline Ring Anchor (MRA) is a ring-shaped anchor designed to be deeply embedded in offshore soils for the purposes of anchoring multiple floating platforms. The increase in offshore development in the wind energy, wave energy and aquaculture sectors requires multiple closely spaced nominally identical platforms that need this type of omni-directional anchor. This novel configuration differs substantially from the typical oil and gas installation and allows consideration of sharing anchors among multiple platforms, thereby driving down capital, material, fabrication and installation costs and duration significantly. Previous simulation-based research conducted by the research team has shown that this concept is feasible but that truly leveraging the advantages of multiline anchoring will require novel anchor designs that can be installed quickly and inexpensively and that also deliver omni-directional capacity and resistance to cyclic loading. To achieve this, the research team will develop models for the loading placed on the anchors from wind, waves and other forces; perform reduced-scale centrifuge tests to provide data on the behavior of MRA systems under these loads; and develop numerical models to assess the behavior of the anchors under multiple loading scenarios. This research project includes a collaboration with an industrial partner, Vryhof Anchors, to ensure that results are driven by the needs of industry and can move rapidly to further industry-driven technology development.

In order to demonstrate proof-of-concept for the MRA, a series of research tasks are planned that will quantify stochastic and time-varying loads placed on the anchor by wind, wave and aquaculture platforms. Additionally, the team will develop conceptual MRA designs based on finite element and plastic limit analysis and assess the suitability of the MRA for sand and clay conditions by a range of methods including centrifuge testing. These tasks will enable the development of fundamental understanding of the response of embedded anchors to cyclic and directionally varying loading. The team will deliver a system evaluation for realistic installations that will provide the impetus for further demonstration-scale research into the MRA. Fundamental advances in understanding the dynamics of interconnected offshore systems as well as the response of deeply embedded anchors in different types of soil to complex loading form the core of the intellectual merit.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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