Optimising pile installation through scour protection (OPIS) project and preliminary findings

<p><span>Scour protection is commonly installed around monopile foundations of offshore wind farms to prevent loss of soil support due to scour erosion. The conventional practice involves a three-step scour protection installation process: (i) placing a filter layer composed of smaller rocks, (ii) installing the monopile through the filter layer, and (iii) positioning the armour layer of larger rocks on top. This workflow requires multiple visits of the rock dumping vessel to the site which increases costs, time spent offshore by the vessels, and consequently carbon emissions. A 3-year joint industry project, Optimizing Pile Installation through Scour Protection (OPIS), has been established in 2023 to streamline the pile and scour protection installations, reducing costs and carbon emissions associated with offshore wind developments and, overall, helping to reach the target of energy transition. The project investigates the technical feasibility of pile installation through coarse rock to enhance the feasibility of the operation. This paper provides an overview of the ongoing OPIS research project, describes its experimental approach, and presents preliminary results. The workflow consists of four branches, namely, three laboratory testing campaigns, and a numerical modelling study. The experimental tests include 357 plate penetration tests, and 313 and 8 pile penetration tests at small and medium scale respectively, and consider different scour protection designs, such as single- and double-layer systems, and different rock densities (high and normal density rocks). The numerical analyses describe the mechanisms at the rock particle level. Preliminary results and challenges encountered during the experiments and numerical analyses are discussed, and innovative solutions devised to overcome specific testing needs are highlighted.</span> </p>