Abstract
Geotechnical engineering has matured sufficiently to contribute to resolving some of society's grand challenges. The 56th Rankine Lecture considered one of the most pressing global problems: maintaining vital energy supplies while also recognising, mitigating and reducing the climate consequences of fossil fuel consumption. This written version reports geotechnical research relating to these wide-ranging issues, considering paired topics within its three main parts and illustrating these with specific practical examples. Part 1 focuses on supporting offshore hydrocarbon production, considering advances in understanding and designing the driven piles that support most continental shelf platforms, before moving to the large underwater landslides that can affect deeper water developments. Part 2 describes investigations into the geotechnical impact of climate change in a permafrost region and a peatland study that contributes to alleviating flood risks exacerbated by climate change. Part 3 outlines research that is improving the economics of renewable offshore wind energy for multi-pile and monopile supported turbines. Integrating geology and rigorous analysis with advanced laboratory and field experiments is shown to be essential to resolving the complex geotechnical problems considered, as is careful full-scale checking and monitoring. Close cooperation with co-workers from industry and academia was central to the studies described and the contributions of many collaborators are emphasised. The concluding section identifies examples of significant questions from each of the six topic areas that remain to be resolved fully.
Highlights
The numerical approach which enabled fully coupled numerical analysis of progressive failure in brittle strata was advanced by Potts et al (1990, 1997) to study earth dams and rail and highway cuts that were usually less than 50 m high
Recent joint studies involving significantly larger pile test datasets and stricter quality criteria include a study by Zhejiang University (ZJU) and Imperial College (ICL), reported by Yang et al (2015, 2017) and a joint industry project led by the Norwegian Geotechnical Institute (NGI) and reported by Lehane et al (2017)
Recognising that relatively few geotechnical engineers work on permafrost problems, the second Part 2 topic calls attention to a more familiar northern European problem to demonstrate the practical ‘nuts and bolts’ of how geotechnical engineering can help to mitigate the hazards posed by future climate change
Summary
Shearing and development of ‘weathered layers’ by advancing ice Deposition of lodgement till by advancing ice. Pile group action is addressed by assuming the interactions are elastic and selecting ‘operational’ profiles of linear shear stiffness with depth. Parallel work at Imperial College allowed predictions to be made by modelling the highly non-linear stiffness behaviour seen from very small strains through to failure in locally instrumented laboratory stress path tests on Magnus till and other soils; see Jardine et al (1984). Finite-element (FE) calculations employing the Imperial College finiteelement program (ICFEP, see Potts & Zdravkovic, 1999, 2001) adopted modified Cam Clay and Mohr–Coulomb
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