This paper outlines the application and extension of the recently proposed PISA design approach, to support foundation design for the Triton Knoll array of monopile supported windturbine generators, which are sited off the UK's east coast and will deliver 855 MW from 2021. Emphasis is placed first on the site characterisation employing in-situ profiling and advanced laboratory testing that allowed location-specific, locally calibrated, 3D FE analyses with the Imperial College Finite Element Code ICFEP. The analyses recognised the small strain stiffness and yielding behaviours of the generally dense sands and stiff glacial till units encountered. The ability of the chosen constitutive models to accurately replicate the most critical features of soil response is demonstrated by comparing single element FE analyses with laboratory test data. Examples are then shown from the comprehensive sets of 3D monopile analyses undertaken of a static loading case that provided predictions for ultimate and service limit states and allowed the extraction of soil reaction curves for use in further design optimisation. The advanced site characterisation and numerical analysis enabled the foundation designers to achieve substantial savings in the project's foundations’ capital costs.
Felix C. Schroeder, Angeliki Grammatikopoulou, Andy Barwise, Stephen MacKinnon, Richard J. Jardine and David M. Potts
Keywords: monopile foundations, finite element analysis, constitutive modelling
Publisher: DFI