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Rankine interview: Outside the lines

nick o'riordan 9305 © thomas graham arup

Nick O’Riordan hopes to challenge the geotechnics industry to think differently when he delivers his Rankine Lecture in March.

Arup fellow and global geotechnics skills leader Nick O’Riordan is the first practitioner in over 25 years to deliver the Rankine Lecture. In his talk entitled “Dynamic soil-structure interaction: understanding the Holocene, instrumenting the Anthropocene”, he hopes the profession will start to think and work outside the lines.

“A lot of it is not found in textbooks, it’s not found in codes, so what we have to do is really understand the ground and make sure we are doing the right thing,” O’Riordan says ahead of his lecture on the 21 March.

It is the soil structure interaction under extreme events that interests O’Riordan the most and in the 58th Rankine Lecture he will be looking at everything from collapses, to wave loading, to train loading, to earthquakes.

O’Riordan believes that geotechnical engineering is at its most unpredictable when under extreme strain and how long it takes for resilient infrastructure to return to functionality is key.

What we have to do is really understand the ground and make sure we are doing the right thing

“In the perfect world, the structure goes with the soil,” he says. “You need to really understand the soil and you have to really understand the structure so that the two can work together during an extreme event. Everything working in harmony.”

But while he believes that codes attempt to deal with extreme circumstances, he also thinks that the industry is suffering from “overcoding” and that this is stifling innovation.

“Codes are designed to make sure things do not fall down, and you can hide your expertise by over designing everything so it is not going to fall down,” adds O’Riordan “but you end up spending money, burning carbon and putting in foundations that are too big.

“It’s all about displacement controlled design, and that goes all the way through from the most highfalutin seismic design through to collapse prevention, the effects of flooding on dams and coastal erosion. With all these things we can look at displacement effects much more closely now by using advance soil models and long term instrumentation installations.

“Young engineers are increasingly taught about codes and there is a perception that because codes are everywhere, there is no freedom, exploration or innovation. That there is no scope to do anything new.”

But O’Riordan believes there is ample scope, and in his lecture he will urge the profession to think outside the box.

“We are not in a displacement controlled world yet,” he explains .“What we have to do is really understand the ground and make sure we are doing the right thing. We know roughly, as engineers, when something is safe, but we don’t really know how safe it is, unless it is tested, until it falls down essentially.

”We design to code, we design buildings to hold roughly 1m of water on every floor, and it is never going to be like that.

“We already have buildings,especially in London, which are never going to see the loads for which they are designed.

“If we instrumented the building, then we could learn how much load the building has actually seen, and there might be no need to put another foundation system in if the building were to be added to or, indeed, replaced.”

Drawing from real life examples in his lecture, O’Riordan will illustrate how the profession should not just be presenting the facts, but winning people over.

“A lot of the work you do is technical, but it is the winning of hearts and minds around your conceptor idea that is key. It is a matter of knowing where you are in the technosociological context as a project materialises,” he explains.

“You can be as technically brilliant as anyone, but if you can’t convince people who would otherwise put a stop to your project, then all your technical brilliance is of no value.”

Academics love studying this sort of stuff, but we are engineers and we can’t wait forever while academics research. 

One of the projects that O’Riordan is currently working on is the construction of the new Mexico City International Airport. The ground is shrinking at a rate of 15mm a month, because the authorities are extracting groundwater for the city’s water supply.

The original airport terminal, located further into the city than the new airport site, was built with dee ppile foundations, which O’Riordan is arguing would not be suitable for the new one.

“We’ve discovered that the effect of all the building in the city is that it has set up a resonance effect, so instead of an earthquake being all over in about 100 seconds, it goes on and on for 200 seconds – like a ripple on a pond.

It’s the buildings themselves which appear to be causing the longer duration of strong earthquakes.

“Up to now, people would have said this is entirely due to a ‘basin effect’, but I think we can now say that the very act of building a city on difficult ground can change the way the city reacts to an earthquake. And it makes things worse.”

O’Riordan and his team managed to find a solution for the airport’s complex soil conditions of very soft Lake Texcoco clays and win over some doubting technical specialists. Essentially the foundations are compensated, and “float’ on and with the ground during operational and extreme events.

“It’s the winning over of hearts and minds and convincing people that we have a robust solution that has taken up the past couple of years on the Mexico City Airport project,” he says.

My favourite project is always the next project. You are only as good as your last project.

“Academics love studying this sort of stuff, but we are engineers and we can’t wait forever while academics research. We have to sort it out, we have to deal with the problems and we design something that works.”

In the unusual position of being licenced as a civil engineer in the UK and in the US, O’Riordan knows that he has the best of both worlds.

“In California you are confronted with seismic design all the time, but here in the UK it hardly ever happens. It might be a one in 10,000 year event for a nuclear power station, but in San Francisco it might be the one in 50 year chance of an earthquake during construction that governs.”

Having worked on a number of impressive projects in California for Arup, including the new foundations for 326m Salesforce Tower, the tallest building in San Francisco, and the nearby Transbay Transit Center substructure, O’Riordan is modest about his accomplishments.

“I’ve been lucky, we kind of fell in love with each other,” he says of his 40 year career with the firm.“I joined when I was 24 and arrived ‘almost fully formed’ from a PhD with the excellent Bob Gibson at King’s College.  It was like being in a box of chocolates working for Arup because there are all sorts of things going on.

”My favourite project is always the next project. You are only as good as your last project, and the next project you want to do even better.”

When asked why he thinks he was chosen over academics to deliver this year’s lecture, O’Riordan says: “I was told they wanted a practitioner who has been around the block and knows some stuff.

“It’s an almost preposterous honour, they have had some very big names. I’m in a rarefied company of characters.”

Career highlights

1977 Graduates from King’s College with BSc in Engineering, tutored by Kevin Nash and Bob Gibson.

1977 Joins Arup in the geotechnical team of 25 people and first project is deep pile testing at the British Library and London Clay modelling with Brian Simpson. Also works with David Henkel and Ken Cole.

1977 Completes a PhD in soil mechanics ‘Consolidation and settlement characteristics of interbedded alluvial deposits’.

1980s works in Baghdad and wrote a seismic design guide with guidance from Nicholas Ambraseys. Other significant projects include the West Midlands limestone mines collapses, Athlone Bridge approach embankments, the National Gallery Extension, Reuters Building, Ravenspurn gravity platform and Torre de Collserola, Barcelona.

1990s Significant projects include working in Paris designing the foundations of a 400m tower in La Defense that was never built, Chatham Maritime: St Mary’s Island regeneration, HS1 ground engineering work for the entire length, and Northwich Salt Mine stabilization.

2007 Moved to Rome and opened Arup’s office in the city. Worked on projects in Florence, Milan, Rome, Naples and Salerno.

2009 Moved to San Francisco, where projects included the Transbay Transit Center foundation system , California High speed rail project in the Central Valley, Sales Force Tower and 181 Fremont St Tower foundations.

2012 Moved back to the UK and began work on Mexico City Airport in early 2015.

O’Riordan is also a visiting professor at Southampton University and an industrial fellow at Bristol University.


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