Date of Award
Master of Business (Research)
Civil, Structural and Environmental Engineering
Mr. David Cadogan
In recent years, the demand for renewable energy in Europe has been rising substantially, as a result of statutory demands put in place by the European Union. It is expected that a relatively large proportion of future renewable electricity will be supplied by offshore wind farms. The offshore wind industry is currently attempting to design and evaluate cost effective foundation systems suitable for water depths greater than 30m. There is also a drive to reduce foundation costs for offshore wind turbines at present. This project is a preliminary feasibility report on an anchored gravity base foundation concept for deployment at water depths of approximately 30m. The purpose of the anchorage system is not to directly provide full rotational resistance against the overturning loads, but to provide increased bearing resistance to the gravity base foundation, which in turn will provide an increased rotational resistance to the foundation unit. The initial stage of this report includes a comprehensive review of literature available on the most recent developments within the offshore wind industry. This includes a discussion of the offshore wind industry on a worldwide basis with Ireland, UK, USA and China being discussed. There is also a review of recent advancements in gravity base design, which includes a number of case studies in relation to recent and proposed projects.
The performance of the anchored gravity base concept is analysed using Finite Element Analysis (FEA) software and is judged on the basis of the rotation of the gravity base under loading. An analysis is carried out for two separate support systems, namely a post-tensioned ground anchor support concept and a grout-injected pile support system, which shows that there is a possible benefit to the inclusion of a piled support in certain soil conditions. This indicates that a reduction in base diameter is possible, potentially resulting in both cost and weight savings. The installation process is reviewed, where recommendations are presented in relation to the installation process for the proposed anchored gravity base.
On the basis that this is a preliminary feasibility report, the research and analysis carried out to date has indicated that there is merit to the anchored gravity base concept, however a number of points are highlighted throughout the report that require further research. It may be critical, in some instances, that these points are investigated in further detail, in order to fully determine the feasibility of the anchored gravity base.
Hayes, Anthony, "Feasibility Report on Use of Anchored Gravity Bases for Offshore Wind Turbines" (2011). Theses [online].
Available at: https://sword.cit.ie/allthe/638