Offshore monopile foundations are one of the most commonly used foundation concepts in offshore renewable energy, especially in areas with relatively shallow water. They are characterised by relatively large geometric dimensions compared with other offshore pile foundations and are distinguished from onshore piles by suffering from harsh ocean environments during their lifetime. One of the most significant aspects is associated with the wave effect on the behaviour of monopile foundations. In this study, a three-dimensional scaled boundary finite element model (SBFEM) is proposed to investigate the structural response of the monopile foundations when exposed to ocean waves. Unlike other numerical techniques, SBFEM provides an analytical solution in the radial direction with numerical approximation along the circumferential and top faces of the monopile foundation, which considerably reduces the computational effort. The SBFEM model is validated by an equivalent finite element model, by which favourable computational efficiency and reliable accuracy are demonstrated. Subsequently, a parametric study is carried out in terms of various wave properties to gain an insight into the monopile behaviour. The purpose of this study is to make recommendations for improving the design of offshore monopile foundations, when wave load is a dominant factor.
Offshore wind farms, as a competitive resource of renewable energy, currently are, and potentially will be, gaining even more global popularity, as they provide higher economic returns and are less obstructive than onshore wind farms. Among the foundation concepts, monopile foundations have been receiving significant attention, particularly when the water depth is no more than 50 meters. They are characterised by a large but simple geometric configuration and localised seabed consumption, consequently simplifying the installation process and minimising environmental disturbance. Furthermore, experience is available from the classic pile foundation topic, which has been studied for decades in both ocean engineering and geotechnical engineering.
