Demonstration of enhanced sliding resistance for ocean energy gravity substructures

Project Description

The objective of this project is to demonstrate enhanced sliding resistance for ocean energy gravity substructures, thereby improving the operational efficiencies of gravity concepts, decreasing the deadweight and optimising the vessel spread used for installation of such devices. The proposed project includes a critical investigation of the behaviour of gravity substructures used for offshore renewable devices (wind, wave and tidal) deployed in sites with rocky outcrops, or coarse materials (such as boulder fields) with the objective of advancing the existing design approach/processes. This will be accomplished through a suite of scaled laboratory testing and advanced numerical modelling, with the objective of advancing the existing design approach/processes. The outcome of the project will benefit wave and tidal sectors by presenting a more refined design approach for gravity substructures that will allow for a more efficient use of material and smaller vessel spread. The results will be made available through a guidance document that can be used by developers to obtain a refined design approach. The project involved the successful completion of laboratory scale testing of different gravity substructure design cases, which was supplemented by advanced numerical analysis using Discrete Element Modelling (DEM) techniques. The outcome of this study showed the existing design standards to be overly conservative in specific conditions, which in practice would lead to excessive costs of construction and deployment. A more efficient design methodology was proposed and implemented within an example substructure gravity base design. The savings in material cost and ultimately the reduced Levilised Cost of Energy (LCOE) were quantified to support the case for adopting more efficient design methods. The lead researchers on this project are Paul Doherty and Soroosh Jalilvand. The final report can be made available on request. Please contact info@gdgeo.com for further details.