Uncharted Territory on the Seabed

Abstract

If the foundations for wind farms are oversized they cause great expense; if they are undersized they endanger the structure. One of the focuses of the RAVE project Monitoring Procedures and Assessment Model for the Foundations of Offshore Wind Turbines was a new type of foundation, the Tripile, used in the BARD Offshore 1 (80 × 5 MW) wind farm. Like a tripod, three piles are driven into the seabed, but rise several metres above the surface of the water, where they are connected with one another by a square transition piece. The aim was to do everything of significance above water. In this project a new procedure was used to determine the pile load displacement curves from the turbine’s operating data. Trials with saturated ground carried out on land showed the pile reaction: on the one hand the load-bearing capacity of the piles increased with standing time, but on the other hand it was reduced by the cyclic loads.