Monday 18 November 2019 saw the successful defence by Iona Richards (REMS Cohort 2) of her DPhil thesis “Monopile Foundations under Complex Cyclic Lateral Loading”. Her examiners were Prof. Torsten Wichtmann (Ruhr-Universität Bochum) and Prof. Chris Martin (Oxford). Iona’s thesis reported her REMS CDT funded experimental and theoretical work exploring monopile foundations under multi-directional and pseudo-random cyclic loading. The examination facilitated a visit by Prof. Wichtmann, along with his two PhD students, Patrick Staubach (Bauhaus Universität Weimar) and Lukas Knittel (Karlsruher Institut für Technologie), for a one day workshop on soil behaviour under cyclic loading, a key issue for offshore wind turbine foundation design.

The first half of the workshop focused on experimental studies, led by Prof. Wichtmann and Lukas Knittel, with experimental findings for low-cycle and high-cycle loading of soils, particularly from soil element testing. The data from a significant range of well specified element tests is used for assessing the performance of different constitutive models, and to identify how to further develop the constitutive models. Talks were then given by Jonathan White (REMS Cohort 2) on triaxial testing at low confining stress and Mark Qiu (REMS Cohort 5) on the new Oxford variable direction cyclic simple shear device. The Oxford work aims also to provide new high-quality data for calibration and development of soil constitutive models.
The discussion then moved to pile behaviour with Prof. Byron Byrne introducing the PISA project and the new Oxford-Ørsted PICASO collaboration, focused on medium scale pile testing in clays and sands. Dr. Rósín Buckley presented results from ALPACA project in south-east England, aimed at understanding pile behaviour in chalk. Finally Wayne Wu (REMS cohort 4) presented model scale pile test results using a bespoke loading rig designed to explore loading rate effects.

Following lunch the focus moved to theoretical work. Patrick Staubach presented new numerical modelling results of foundations under time-varying cyclic loading, including pile driving installation, using a soil model developed by Prof. Wichtmann’s team. Prof. Guy Houlsby then outlined the hyperplasticity approach for predicting soil behaviour under cyclic loading, with Luc Simonin (REMS Cohort 5) and Toby Balaam (REMS Cohort 3) demonstrating different ways in which this modelling approach could be applied.
The Royal Oak was a perfect location for a pre-dinner drink following the day’s discussion of cyclic loading, followed by a meal at Carluccio’s on Little Clarendon Street. We hope that the two groups will continue to work with each other in the future, and all look forward to making a return visit to Prof. Wichtmann’s group in Germany!