German engineering outfit Bauer Spezialtiefbau has tested a new piling system for Ailes Marines’ 496 MW Saint-Brieuc wind farm off France.
Bauer installed and removed 14 onshore test piles for the wind farm at an active quarry near Cap Frehel in Brittany.
Saint-Brieuc will deploy the new piling method for its jacket foundations, which will be built by a Navantia-Windar consortium.
“It will be the first commercial application for this type of piles worldwide. Bauer has developed a special drilling system for such projects in order to install temporary cased drilled and grouted piles offshore in a variety of different types of subsoil,” Bauer Spezialtiefbau head of underwater foundations Paul Scheller said.
The tests were aimed at gathering friction values for the foundations and cited ultra hard rocks as the biggest challenge during the test campaign.
“Drilling the 1,350 mm diameter piles took much longer than expected and resulted in excessive wear on the roller bit core barrels that were used,” Bauer project manager Niklas Haag explained.
Once drilled, test loads of between 10 MN and 40 MN were applied to the piles and a geo-laser system to recorded uplift around each tubular, recording the movement every ten seconds.
The Saint-Brieuc project will feature 62 Siemens Gamesa 8MW turbines and is due online in 2022.