A monopile foundation is a mature, cost-effective and efficient option for offshore wind turbine foundations (hereinafter referred to as OWTs); over 79% of offshore wind turbines are built with this type of foundation in Europe. However, Scour hole development may seriously threaten the performance of the foundation. Traditionally, a riprap scour protection constructed of filter and amour layers is applied to reduce scour around OWTs in engineering practice. This method has also been widely investigated and researched. Deltares provided the Handbook of Scour and Cable Protection Methods (Deltares, 2023), which contains generic design guidance for riprap protection of offshore support structures. Combining a riprap scour protection with alternative protection methods (like collars), could lead to a significant performance improvement in resisting scour and thus a smaller environmental footprint. Using the circular collar as a stand-alone solution was found to have very limited protection efficiency (Tang et al., 2023; Zhang et al., 2021), but there is great potential for improvement when combining it with a riprap protection. This paper aims to quantify the scour protection performance of these innovative structures through data analysis on small-scale wave experiments and find a more efficient scour protection measure, which will open new possibilities and insights into future scour protection design in offshore engineering. 

scour protection approach,offshore,scour,monopile,collar