Large Diameter Pile Testing for Offshore Wind Applications with a Focus on Cyclic Lateral Loading and Rate Effects-Paper

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The PICASO project, a collaboration between Oxford University and Ørsted, aims to improve the design of offshore wind monopile foundations by accounting for cyclic loading and loading-rate effects—factors not adequately addressed by existing design methods.<br /><br />The project builds on the PISA research, which developed practical design methods largely focused on monotonic loading. PICASO will develop and validate new cyclic-loading models using theory, laboratory research and medium-scale field tests at two sites intended to represent common offshore ground conditions: stiff, overconsolidated glacial clay and medium-dense to dense silica sand.<br /><br />At each site, the programme plans to test 11 instrumented steel piles, 1.22–2.5 m in diameter, alongside reaction piles. Tests will examine monotonic and multi-rate behaviour, several forms of cyclic loading—including symmetric, asymmetric and pseudo-random loading—and changes in pile response after cycling. Some tests will apply loads in multiple directions. The piles will be tested first at the clay site and then reused at the sand site.<br /><br />The clay site investigation includes cone penetration and seismic cone tests, boreholes, groundwater monitoring and laboratory testing. Pile response will be measured using fibre-optic strain sensors, inclinometers, load cells and displacement transducers. The programme is designed to provide high-quality data for numerical analysis and to validate methods that can ultimately be integrated into turbine models to assess long-term foundation performance.

Keywords

PICASO

offshore wind

monopile foundations

cyclic loading

loading-rate effects

PISA research

instrumented steel piles

glacial clay

silica sand

foundation performance