DESIGN AND OPTIMIZATION OF SCOUR PROTECTION FOR OFFSHORE WIND PLATFORM DOLWIN BETA

DolWin Beta is a large offshore power converter platform, which will be used to connect multiple offshore wind farms off the German coast to the main land. It will be located in a water depth of 29m, where tidal currents and harsh wave conditions may cause soil erosion (scour) and possibly undermining of the foundation if not protected properly. Laboratory experiments were conducted in order to investigate the scouring around the foundation and provide an optimized layout for scour protection. This paper summarizes the initial scour assessment, the design approach for scour protection, the experimental setup, test program, monitoring techniques and results of the experiments. The test results revealed which zones of the scour protection around the foundation were most sensitive to shear failure and edge scour. In steps, the scour protection was strengthened in these zones and reduced in the more sheltered areas. The tests showed that the magnitude of rock displacement, apart from wave height and direction, was significantly influenced by the superimposed current velocity. Based on a test without scour protection, the sequence of installation was adjusted to minimize risks of scour during installation. Finally, a stable scour protection layout was obtained that was fully verified under extreme storms and long-term effects of edge scour.