Analysis of offshore soils and foundations for wind deployment in the Italian seas in intermediate water depths

The offshore wind energy sector poses unique geotechnical challenges due to the complexity of the structures and the peculiarity of the environment. Aspects that cannot be dealt with conventional knowledge maturated in completely different contexts. As a consequence, specific methodologies and solutions are required. Actively taking part to the debate on the future Italian energy supply, the doctoral thesis aims to provide an overview from a geotechnical standpoint of the main characteristics of the Italian seabed along the eastern coast. A database is built starting from the experience and data gained in the Italian Oil and Gas industry over the past decades, which comprises data related to cone penetration tests (CPT), soil characterization and results from laboratory tests. The data stored in the database and results of technical-scale experimental campaigns conducted on traditional open-ended steel piles and innovative suction-installed bucket foundations, both installed in medium dense sand, are used to develop and validate suitable numerical procedures capable of simulating the behaviour of foundations for offshore wind turbines (OWTs) when installed and under in-service loading conditions. Finite Element (FE) model results served as a basis for the development of a formulation for load-transfer curves (t-z) to predict the drained load-displacement behaviour of offshore steel piles subjected to axial tensile loading. This condition is particularly relevant to foundations for wind turbines in intermediate to deep water, which are commonly encountered along the Italian coasts.