In recent years, there has been significant interest in new approaches for the geotechnical design of monopiles for the rapidly expanding offshore wind industry. There is a requirement within the offshore industry to have design approaches which are computationally inexpensive so that many thousands of design iterations may be run in order to optimise a wind farm layout. While 3D Finite Element (FE) modelling is still regarded as being too costly to run all the required design iterations, new combined approaches have been proposed, such as the PISA design model, which involve the extraction of soil reaction curves from 3D FE models which can apply in simpler beam-spring models. For proper implementation of these new approaches, it is imperative that the base case 3D FE soil models are correctly calibrated so as to accurately capture the pile response. This paper proposes a new approach for deriving the soil parameters required to accurately model a monopile’s response in sand using the small-strain hardening (HSsmall) soil model. The procedure offers a consistent approach to develop all the required soil input parameters, using Cone Penetration Testing data as the primary input, and is validated against a newly collated database of large scale monopile field tests. By using CPT data, the new approach is essentially user independent, and is shown to be remarkably accurate when compared with high quality field tests covering a range of monopile geometries at three sand test sites.
David J. P. Igoe and Soroosh Jalilvand
Keywords: Monopiles, Offshore Wind, FE modelling
Publisher: DFI