3D FE cyclic modelling of monopiles in sand using SANISAND-MS: Calibration and validation from soil element to pile-interaction scale

Understanding and accurately modelling monopile behaviour is a central challenge in modern offshore wind geotechnics, often requiring, for detailed design, robust finite-element (FE) simulations supported by well-calibrated constitutive models. This study critically evaluates and advances the application of 3D FE modelling for laterally loaded monopiles using the SANISAND-MS model, informed by a comprehensive experimental programme ranging from element-scale testing to centrifuge modelling under both monotonic and cyclic loading, in dry and saturated sand. This work investigates strategies for the reliable calibration of the SANISAND-MS constitutive model. Key calibration challenges are addressed, including limitations in test data availability, variability in material response, and the alignment of model parameters with soil strain levels representative of realistic operational scenarios. The study further highlights practical considerations and limitations associated with the use of SANISAND-MS, particularly when extrapolating features of foundation response observed in physical modelling to full-scale conditions. For the cases considered herein, comparisons between numerical simulations and experimental data show good agreement in dry conditions, whereas reduced accuracy in saturated cases underscores the need for a more detailed treatment of, among other factors, soil–pile interface behaviour and loading-rate effects on excess pore water pressure generation. Overall, the findings provide valuable guidance for improving the fidelity of advanced FE simulations for offshore monopile design.