Optimising suction bucket foundation installation for offshore renewable energy infrastructure through field data on self-weight penetration

Abstract

In recent years, the suction bucket foundation (SBF) has emerged as a preferred option for offshore wind turbines. However, accurately predicting penetration resistance remains a critical challenge, essential for determining self-weight penetration depth and the required suction during installation. Typically, SBF installation comprises two phases: the self-weight penetration phase and the suction-assisted installation phase. The current cone penetration test (CPT)-based prediction method primarily focuses on the suction installation phase, utilising only one set of design parameters (i.e. k_p and k_f). As a result, design parameters are typically calibrated against available installation data to achieve agreement for the suction installation phase, overlooking discrepancies in the predicted self-weight installation phase. The accuracy of predicted self-weight penetration significantly influences the evaluation of lifting crane operation, safety, the magnitude of suction pressure, and tilt of the suction bucket foundation system. This study addresses the reasons for these discrepancies and identifies shortcomings in the current CPT method. It introduces a new set of design parameters for evaluating the self-weight penetration phase, incorporating soil classification and distinguishing between the self-weight penetration (SWP) and suction penetration phases. Leveraging data from 35 SBF field installation sites in the South China Sea, back calculations are conducted to propose design parameters for SWP depth evaluation. The study underscores the importance of considering SBF installation in two distinct phases, providing fresh insights for enhanced design guidance, and highlights the economic and technical advancements in design practice with the new set of design parameters for SWP.