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The PISA design model is a procedure for the analysis of monopile foundations for offshore wind turbine applications. This design model has been previously calibrated for homogeneous soils; this paper extends the modelling approach to the analysis of monopiles installed at sites where the soil profile is layered. The paper describes a computational study on monopiles embedded in layered soil configurations comprising selected combinations of soft and stiff clay and sand at a range of relative densities. The study comprises (a) analyses of monopile behaviour using detailed three-dimensional (3D) finite-element analysis, and (b) calculations employing the PISA design model. Results from the 3D analyses are used to explore the various influences that soil layering has on the performance of the monopile. The fidelity of the PISA design model is assessed by comparisons with data obtained from equivalent 3D finite-element analyses, demonstrating a good agreement in most cases. This comparative study demonstrates that the PISA design model can be applied successfully to layered soil configurations, except in certain cases involving combinations of very soft clay and very dense sand. [ABSTRACT FROM AUTHOR]

This paper describes a one-dimensional (1D) computational model for the analysis and design of laterally loaded monopile foundations for offshore wind turbine applications. The model represents the monopile as an embedded beam and specially formulated functions, referred to as soil reaction curves, are employed to represent the various components of soil reaction that are assumed to act on the pile. This design model was an outcome of a recently completed joint industry research project – known as PISA – on the development of new procedures for the design of monopile foundations for offshore wind applications. The overall framework of the model, and an application to a stiff glacial clay till soil, is described in a companion paper by Byrne and co-workers; the current paper describes an alternative formulation that has been developed for soil reaction curves that are applicable to monopiles installed at offshore homogeneous sand sites, for drained loading. The 1D model is calibrated using data from a set of three-dimensional finite-element analyses, conducted over a calibration space comprising pile geometries, loading configurations and soil relative densities that span typical design values. The performance of the model is demonstrated by the analysis of example design cases. The current form of the model is applicable to homogeneous soil and monotonic loading, although extensions to soil layering and cyclic loading are possible. [ABSTRACT FROM AUTHOR]

Experimental and computational data are presented for Areolas da Estefania, a geomaterial which is crucial for the development of the underground infrastructure of the city of Lisbon, Portugal. The experimental data comprise the particle size distribution of the material and measurements obtained during a series of strain-controlled triaxial compression tests performed on intact samples. The behaviour of this material at a wide range of strains, under constant mean effective stress levels of 130 kPa, 300 kPa and 400 kPa is established, with the presented dataset containing information on stress (mean effective stress and deviatoric stress) and strain states (axial strain and volumetric strain). These are complemented by the results of bender element tests imposing vertically-travelling waves for characterisation at very small strains. Complementarily, the computational dataset establishes a reference reproduction of the response of Areolas da Estefania using a material model which combines a non-linear small stiffness formulation with a state-dependent strength and plastic dilatancy. Overall, this dataset can be used as a reference when assessing the behaviour of other samples of Areolas da Estefania or comparable materials, or when evaluating constitutive models for granular geomaterials., (© 2024 The Author(s).)