ICE-PICK: Installation effects on cyclic axial and lateral performance of displacement piles in chalk

Never in human history has there been such an urgent need for a step-change in energy production. With the goal of achieving a carbon neutral state by 2050, the UK is the first major economy to pass net zero emissions laws and lead the world by example. In answer to this impellent necessity, offshore renewables -particularly wind- are expanding at a rapid pace. Many of UK's offshore wind turbines (OWT) developments will need to be fixed or anchored in chalk, a highly variable soft rock that covers much of Northern Europe and is widespread under the North and Baltic Seas. In most cases that will be achieved by pushing or driving large steel piles into this soft rock under the seabed. That installation process is difficult because of the unprecedented scale of some of these foundations (monopiles), because the conditions of the chalk at the interface modified by installation are poorly known, the mechanical behaviour of chalk is complex and because working offshore leaves little room for error. Apart from its inherent difficulty, the installation process essentially modifies the chalk around the foundation. As a result of those changes, there are still some important gaps in our ability to predict properties that are basic for safe and efficient operation, such as the initial and the evolved axial capacity and lateral stiffness of monopiles through their in-service lifetime characterised by complex wind and wave cyclic load history.

The research proposed will improve the efficiency and cost effectiveness of piles driven in soft rocks to support the further development of renewable energy structures offshore through rigorous numerical and experimental modelling. The key aims are to improve pile drivability assessment for open-ended piles supporting OWT and to quantify the effects of installation on long-term in-service performance of OWT foundations. The main deliverable will be to develop practical tools to incorporate these effects within engineering analysis and design suitable for both onshore and offshore applications.