Kate Emily Porter, Richard Simons, John Harris, Tiago Fazeres Ferradosa


Offshore windfarms are often situated in complex sediment beds made up of layers and mixtures of sands, gravels and clays. However, little is known about how these types of sediment beds actually affect the scour process. Therefore, a series of laboratory tests were conducted to test simplified cases of layered and mixed sediment beds, as a basis for improving understanding of scour in complex situations. Two sands were used in the tests; one fine and one coarse with 0.2 and 0.6mm respective median grain sizes. In the layered case with fine sand as the upper layer, it was found that scour development in the underlying coarse sand was enhanced compared to scour in a uniform bed of the coarse sand. In the mixed case the shape of the scour curve was significantly altered as were the time to equilibrium and equilibrium scour depth.


scour; clear water; current; layered sediments; mixed sediments

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