FE Modelling of Monopiles in Sand Under Monotonic and Cyclic Lateral Loads

This study simulates a monopile in sand under monotonic and cyclic loads in a 3D FE model. Sand’s behaviour is modelled using SANISAND-MS, a critical state-compatible bounding-surface plasticity constitutive model formulated to improve the prediction of cyclic ratcheting. 3D pile models considering and neglecting a simplified representation of pile installation effects are adopted. The installation effect is simplified and modelled by applying a positive volumetric strain of the soil plug. The results obtained in the “wished-in-place” pile show that the load–displacement curve of the monotonic analysis is in good agreement with the selected field data of the PISA project and only the rate of accumulation of the relative displacement is captured. By accounting for installation effects, higher initial stiffness of the load–displacement curve at early loading stages and realistic estimation of the pile accumulated relative displacement pile are observed, remarking the limitation of the common “wished-in-place” approach.