Offshore engineering will be the focus of Guy Houlsby’s Rankine Lecture in March, but selecting whether to discuss a practical or theoretical topic was not a straightforward choice.
Being selected to deliver the Rankine Lecture is often seen as one of the pinnacles of a career in geotechnics, not just in the UK but internationally. This year the honour of delivering the 54th lecture goes to Oxford University head of engineering science and professor of civil engineering Guy Houlsby.
Houlsby is due to deliver his lecture “Interaction of foundations in offshore design” at Imperial College in London on 19 March, but selecting the topic, as well as the timing, was a challenge, he says.
Houlsby says that in one sense the invitation to present the 2014 Rankine Lecture was bad timing as he has been deeply involved in the Research Excellence Framework,which the Higher Education Funding Council for England carries out every six years. “It is very important as it is worth around £25M to the department and had to be submitted at the end of October last year,” Houlsby explains. “As a result I only started to focus on the lecture towards the end of last year. It is a real honour to be asked to deliver the lecture though.
“My interest in research has always had two threads – one is fundamental and the other is practical,” he says. “I think it is good to have both angles but some prefer to try to be the world expert in one subject.”
Houlsby’s theoretical research subject is a continuation of his PhD thesis on plasticity theory and thermodynamics. “It draws on my mathematical bent,” he says. “I would have loved to have delivered my lecture on that topic but that would have been self-indulgent, so I have chosen a topic from the other area of my research as I believe the applied side is more relevant to more people.”
There are a number of different areas in the applied side of geotechnics that interest Houlsby, including insitu testing, reinforced soil, tunnelling and offshore. “The demand for offshore engineering solutions is a recurring theme, which is why I selected that area to explore in the lecture,” he says.
There will be three parts to the lecture. The first and second will be based on Houlsby’s experience from the oil and gas industry and the use by this industry of jack up units. The final part will focus on foundations for offshore wind farms.
“I would describe content as forward thinking and speculative,” he says.
It is the final section where Houlsby intends to focus most of the lecture and will cover the current foundation solution of monopiles, unconventional solutions such as suction caissons, and some completely novel ideas including the helical piling solution that his Oxford colleague Byron Byrne has been investigating.
“Helical piles are not actually new to the sector – I have discovered that helical piles were used for a lighthouse in the 1840s,” he points out. “They worked but were not publicised.”
According to Houlsby, the use of the word interaction in the title of the lecture is a deliberate pun. “I am referring to both the physical interactions of the foundations and our professional interactions with other disciplines,” he explains.
“I could have done a whole lecture on the wind turbine problem but you can’t disentangle the foundations from the turbine, nacelle, control systems and connectivity to the grid.”
The main message in part one is for engineers to learn more statistics.“Maths is a rational way to treat the problem,” says Houlsby. “Soil mechanics cries out for the application of statistics but most geotechnical engineers will shy away from the subject but it is not an excuse not to learn. All engineers are numerate but they tend to prefer mechanics and that is what may have led them into engineering.”
The message in part two is closer to home, he says. “It centres round communication with structural engineers. There is a good example of the issue in jack up units – structural engineers ask for springs on the bottom of analysis for soil interaction and geotechnical engineers will pat them on the head and say that it is much more complex than that.
“What is needed is to customise geotechnical knowledge into an accessible form for structural engineers and for structural engineers to understand that the issue is more complicated than springs.”
“Offshore wind is moving into deeper water and using larger turbines”
In the final part of the lecture, Houlsby says he will look at new problems and new innovation, as well as trying to look at what geotechnics can learn from the offshore oil and gas industry.
Houlsby believes that there are lots of good challenges ahead. “Offshore wind is moving into deeper water and using larger turbines,” he says. “125m diameter rotors are now routine, but there some that measure up to 180m in diameter on the drawing board.”
Houlsby is well placed to know what lies ahead as he is part of the Pile Soil Analysis (Pisa) project which is a collaboration between Oxford University, Imperial College and University College
Dublin and an industry working group led by Dong Energy and including RWE, Statoil, Statkraft, SSE,
Scottish Power and Vattenfall. The scheme is being run under the framework of the Carbon Trust
Offshore Wind Accelerator (OWA), a UK government supported organisation established to promote offshore wind energy and reduce the cost of energy.
The project is about to go out into the field with large-scale tests planned later this year. The aim of the working group is to find technological solutions to be implemented in time for the design and construction of the large Round 3 offshore wind projects in the UK. The working group will be publishing its final reports at the start of 2015.
Engineering was not Houlsby’s initial choice of career, but after hearing a lecture from Peter Wroth he was hooked on geotechnics. “I nearly chose to read maths and it was a choice between maths and natural science at one point and my late decision to opt for engineering at Cambridge University was motivated by a friend,” he says. What attracted Houlsby to soil mechanics was that it was the first time in his engineering education where he had been told about a problem that was not yet solved. The drive to find solutions led Houlsby undertake a theoretical soil mechanics related project in his final year.
On graduation Houlsby joined Binnie & Partners in London to fulfil his ambition to deliver consultancy services on big dam projects and later joined Babtie, Shaw & Morton to work on the Kielder Dam to gain on-site experience.
After completing his PhD at Cambridge in 1980 under the guidance of Wroth, Houlsby was torn between continuing in the field of research and becoming professionally qualified.
“I was encouraged to apply for a research fellow position at Oxford when I finished by Peter, who had moved to Oxford just before I competed my PhD,” he says. “At that stage I still planned to go back to construction but I got bitten by the academic side of geotechnics. I enjoyed my time in construction but I didn’t want my boss’s job.”
Houlsby worked with Wroth to build up the department at Oxford and soon became a soil mechanics lecturer and tutor at Keble College.
Houlsby was appointed to the chair in 1991 and at 36 he was the youngest engineering professor at Oxford at the time. He became head of department in 2009 – a role that will end next summer, but he says that he still has another six or seven years before considering retirement.