Conventional scour protection installation around monopiles for offshore wind farms involves placement of smaller filter layer rocks and larger armor layer rocks in two separate operations, requiring multiple visits of the rock dumping vessel to the site which increases costs, time spent offshore by the vessels, and consequently carbon emissions. The joint industry project Optimizing Pile Installation through Scour Protection (OPIS), established in 2023, helps reaching the target of energy transmission by streamlining the pile and scour protection installations, reducing costs and carbon emissions associated with offshore wind developments. The project investigates the technical feasibility of pile installation through coarse rock to enhance the feasibility of the operation. A series of small and medium scale laboratory experiments has been conducted, considering different scour protection designs such as single- and double-layer systems, and different rock densities (high and normal density rocks). This paper delves into the physical modelling aspects of the OPIS research project. Furthermore, this contribution elaborates on the design and intricacies of the scaled laboratory tests, providing in-depth insights into the design and implementation of laboratory setups, along with a detailed account of experimental procedures. Moreover, preliminary results and challenges encountered during the experiments are discussed, and innovative solutions devised to overcome specific challenges are highlighted.

The offshore wind industry has grown significantly over the past decade with the increasing demand for clean energy, and over 80% of offshore wind turbines have monopile foundations. The installation of these foundations requires monopiles to penetrate several pre-installed scour protection rock layers before reaching the required penetration depth. With the increasing sizes of both monopiles and the extent of scour protection layers, various challenges arise during the monopile’s driving and self-weight penetration process, such as misalignment and early pile refusal. Lab scale testing and empirical modelling are time-consuming and normally not general enough to be applied to different scenarios. Within the Optimising Pile Installation through Scour Protection (OPIS) project, the high fidelity discrete element method (DEM) has been deployed to consider both the discrete nature and shapes of the scour protection rocks. A double-layer (armour & filter) scour protection with a sand layer underneath was simulated using the DEM. Detailed rock dynamics and the armour rocks dragging down during penetration are revealed and particle-geometry rolling friction is identified as the dominant parameter. The effects of the sand layer thickness and pile wall thickness on penetration resistance are also addressed.