Industry-linked PhD Studentship: Investigation of Suction Caisson Behaviour under Pressure Cycling

Suction caissons are a type of foundation commonly used to support offshore wind turbines in deep waters. They are installed by pumping water out of the caisson to create a ‘suction pressure’ (i.e. negative pressure relative to the ambient pressure) inside. Pressure cycling, which involves the cycling of the suction pressure, is often used to continue caisson penetration into the seabed when constant suction pressure is not effective. However, there is currently no method for predicting caisson penetration under pressure cycling, which can lead to significant uncertainty. There is also a critical lack of understanding of the potential effects of pressure cycling on the subsequent in-service performance of the caisson.

The aim of the PhD project is to develop a better understanding of the pressure cycling procedure and its effect on the caisson penetration behaviour during installation and the caisson in-service performance post-installation. The PhD candidate is expected to carry out the following activities to achieve the aim of the project:

(1) Implement large deformation finite element analysis to numerically simulate pressure cycling installation of suction caissons in clay and sand in order to investigate the effects of pressure cycling on the caisson penetration behaviour during installation and the caisson in-service performance post-installation.

(2) Conduct 1g model scale testing of pressure cycling installation of suction caissons in clay and sand in the laboratory to supplement findings from the numerical modelling.

(3) Develop a new design method to predict caisson penetration under pressure cycling