Medium scale field testing of laterally loaded monopiles in glacial till at Cowden for the PICASO project
Sarah Martin and Professor Byron Byrne
The offshore wind industry has grown rapidly over the past decade as the world seeks secure and renewable sources of energy. Significant expansion of the industry over the next decade is anticipated across UK, Europe, USA, China, Japan and now Australia. Offshore wind turbines are often located on “monopile” foundations, large diameter tubular steel piles that are typically impact driven into the seabed. Recently the PISA (Pile Soil Analysis) project developed new design procedures for the monotonic lateral loading capacity of monopiles, now widely used by developers in Europe and elsewhere. However, the PISA and other methods, do not properly account for cyclic loading and rate effects, which is the focus of current industry and academic studies. The PICASO (Pile Cyclic Analysis: Oxford and Ørsted) project is a collaboration between Oxford University and Ørsted, which aims to develop a new design method focused on addressing cyclic lateral loading.
This presentation will provide a background to offshore wind in UK and Europe, and recent developments in design guidance, such as from the PISA project. A high-level background to cyclic lateral loading of piles will be given, including new approaches to modelling of cyclic loading, followed by an introduction to the range of work being completed through the PICASO project. A central component of the work was the medium scale field testing, which provides new evidence of pile cyclic loading behaviour, against which design methods can be tested. 11 test piles, of diameters 1.22 m and 2.5 m, were installed by impact driving at an over-consolidated glacial till site in Cowden, Hull, UK in 2020. The site characterisation and analysis of the pile installation will be discussed. An overview of the cyclic loading tests completed will be given, including uniform amplitude cycling and pseudo-random cycling to represent “storm” events.
About the speaker
Sarah Martin Associate Geotechnical Engineer, Offshore Geosciences Team, WSP
Sarah is an Associate Geotechnical Engineer in the WSP Offshore Geosciences Team in Perth. Sarah spent the first six years of her career as a Geotechnical Engineer with Golder Associates (now WSP) in Brisbane, predominantly working in the infrastructure sector. Sarah shifted her focus to offshore geotechnical engineering by pursuing her DPhil at the University of Oxford, commencing in late 2018 and currently awaiting final assessment. She was funded by an Ørsted studentship and was part of the Renewable Energy Marine Structures (REMS) Centre for Doctoral Training (CDT). Sarah’s research had a practical focus, centring on medium scale field testing for monopile foundations in over-consolidated clay soils. This research is a key component of the Pile Cyclic Analysis: Oxford and Ørsted (PICASO) Project which seeks to develop improved design methods for cyclic lateral loading, building on the success of the Pile Cyclic Analysis (PISA) project for monotonic lateral loading.
Professor Byron Byrne Ørsted / Royal Academy of Engineering Research Chair in Advanced Geotechnical Design, Oxford University
Photo © Copyright, University of Oxford
Professor Byron Byrne holds the Ørsted / Royal Academy of Engineering Research Chair in Advanced Geotechnical Design at Oxford. He is also Professor of Engineering Science in Civil Engineering and a Fellow at St Catherine’s College. He is the Oxford Director for the EPSRC funded Centre for Doctoral Training in Renewable Energy Marine Structures, a Co-Investigator for the EPSRC funded Centre for Doctoral Training in Wind and Marine Energy Systems and Structures and a Co-Director of the EPSRC Supergen Offshore Renewable Energy Hub. He is an Associate of the Geotechnical Consulting Group in London. He is a Fellow of the Royal Academy of Engineering and the Institution of Civil Engineers.
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