Investigation of Soil Reaction Curves Extracted From 3D FE Models

Monopiles are the preferred type of support structures for offshore wind turbines due to their technical and economical suitability. Monopiles have been designed for a long time using recommendations drawn from the Oil and Gas industry such as the API/DNV guidelines, which were shown to be unreliable for the design of large diameter piles, as the recommendations have been formulated for much slender ones. New design methodologies have since then been developed, namely the PISA methodology in which in situ testing and advanced simulations were carried out on piles having a comparable aspect ratio L/D as monopiles used in the offshore wind industry. In this paper, the soil reaction curves are extracted from a 3D Finite Element model of the monopile and the surrounding soil, using lateral pushover analysis. The soil is modelled using advanced sand and clay constitutive models which were calibrated using laboratory as well as in situ test results. The extracted reaction curves are compared to the input rule-based PISA reaction curves used in 1D monopile beam-column models. The results are compared and conclusions are drawn.