Wind parks in the German Bight - a challenge for geotechnics After a presentation on the VDI conference "Oscillation of wind energy plants", February 2011 in Bremen/Germany

The foundations for offshore wind energy plants (OWEP) in the German Bight, with water depths of up to 30 m, are a challenge. Waves more than 20 m high can turn over meters of sandy ground, they tilt and lift embedded structures and can lead to capsizing. The sand can be re-consolidated by normal waves, and some foundations right themselves and settle. This is due to the material properties of sand, which cannot easily be explained and can only partly be quantified. Some mechanisms of OWEP foundations can be observed in model tests, others in field tests and pilot plants. Scenarios with extreme waves require physically sound methods; code methods do not suffice. Experience with offshore production platforms cannot simply be transferred and is anyway often kept secret. Thus one has to break new ground for planning, building and maintenance of OWEP foundations.