Universal Foundation Norway engaged Empire Engineering to assist with repair works at Dogger Bank wind farm.
The Dogger Bank wind farm is the biggest wind farm in the world and a joint venture between SSE Renewables and Equinor. This large scale project is situated off the East coast of England in the North Sea with over 190 foundations. The wind farm includes a range of turbine sizes from 12MW right up to 30MW.
Revolutionary Foundation Design
In October 2011, Universal Foundation Norway (previously Fred Olsen United) was awarded the contract for the turnkey installation of 2 meteorological masts at Dogger Bank. The contract incorporated Universal Foundation’s revolutionary and innovative foundation design and was delivered by Fred Olsen related partners.
The installation and commissioning was completed in September 2013: it was the first project of its kind and a key milestone in the commercialisation of the foundation technology – achieving cost and time saving goals and noise reduction targets.
Vital Repairs Needed
Following the detection of significant cracks in the structures primary steel, Empire Engineering advised how to safely dismantle and repair the compromised structure. The first stage was detailed finite element analysis coupled with fatigue analysis, to determine the root cause of the failure.
Once the mechanism was well understood, Empire were then able to advise how to safely disassemble the structure. Because of the unusual nature of the problem, a bespoke risk-based analysis was developed to justify safe operational weather windows to have vessels near the structure, as well as crew. The lifting analysis was also particularly challenging, as it needed to show that the structural cracks would not be overloaded during the lift.
Project Evaluation
In designing the repair works, Empire analysed strain to determine which of the existing structural members had suffered significant fatigue damage and could not be re-used, and importantly identified which parts of the structure could be safely re-used. Several repair concepts were quickly evaluated, with the best concept then being developed into a fully detailed repair design.
Reports suitable for independent certification were then submitted to the client. Empire also provided on-site inspection to ensure that the repair was completed in-line with the design intent.
