Predicting the installation of pushed-in cluster piles for offshore wind foundations in sand

The pushed-in cluster pile concept consists of the cyclic jacking of four closely spaced piles in a sequence, such that one pile is jacked while the other three act as reaction piles, enabling deeper embedment than static weight alone can provide. The method offers a low-noise alternative for offshore wind foundation installation, addressing increasing environmental constraints and the need for scalable solutions. This study presents a comprehensive experimental investigation using 38 centrifuge tests to evaluate the performance of closely spaced pile clusters jacked into sand. Key mechanisms such as pile plugging, enhanced pile penetration resistance and installation efficiency are examined, while an optimum installation sequence is determined. A novel cone penetration test-based predictive framework is developed and validated, linking single pile resistance to cluster performance through installation efficiency. The model accurately forecasts refusal depth and enables optimisation of pile diameter, spacing and tool weight. Results demonstrate that pushed-in pile clusters can achieve up to 5 times greater penetration than static embedment, offering a promising foundation solution for offshore wind applications with reduced environmental impact.