The Sheffield researchers blowing things up in the name of science in the Peak District

The Peak District is known for its serene beauty but some very noisy neighbours from the University of Sheffield are shattering the peace.

Wednesday, 3rd March 2021, 9:53 am

Thankfully it’s not all-night parties but groundbreaking scientific research which is causing such a din in the heart of the national park, where the roar of explosions can be heard rippling through the air most days.

The potentially life-saving experiments are taking place at a remote former Second World War munitions site outside Buxton, where the nearest neighbours are on a farm located a few kilometres away.

The Blast and Impact Research Group, part of the university’s Department of Civil and Structural Engineering, are the ones blowing things up so they can examine in minute detail the forces created and the effects on different structures and materials.

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Dr Sam Rigby, who is a member of the Blast and Impact Research Group (pic: Blast and Impact Research Group/University of Sheffield)

Dr Sam Rigby, one of three post-doctoral researchers on the team of about 25, says: “It kind of feels like I’ve never grown up. If you’d asked a 10-year-old Sam what he wanted to do for a living he probably would have said take things into a field and blow them up.”

But the work Dr Rigby and his colleagues are doing has serious practical implications, helping to prevent deaths and serious injuries everywhere from war zones to government buildings and busy shopping streets in the event of a terrorist attack.

By improving our understanding of the mechanics behind explosions and exactly how they cause such destruction, they enable engineers and architects to better design buildings and vehicles to minimise the devastation caused by a bomb detonating.

A landmine test carried out by the Blast and Impact Research Group at its base near Buxton (pic: Blast and Impact Research Group/University of Sheffield)

“The thing I enjoy about this research is that it’s scientifically challenging and there’s a lot of academic work to be done but ultimately it’s to save lives and help protect people,” says Dr Rigby.

One of the team’s biggest projects to date involved working with the Ministry of Defence to examine the forces created – or ‘loading’, to use the scientific term – by buried explosives.

“They wanted to know basically how do the burial conditions affect the output from a landmine,” explains Dr Rigby.

Stills from high speed video of a partially-buried explosion carried out by the Blast and Impact Research Group (pic: Blast and Impact Research Group/University of Sheffield)

"Our work showed there was a certain kind of soil which led to a noticeable difference in the loading, to the extent the MoD was able to say if we’re going on operations and we know the different soil types in the area we can avoid certain routes because they would involve going over ground where there’s a significantly increased risk to our troops if they hit a landmine.”

The team have had to develop world-leading apparatus to measure the huge pressures being exerted in the tiniest fractions of a second.

As Dr Rigby explains: “Pound for pound, the energy in a high explosive is about the same as in a Mars Bar, but if you eat a chocolate bar that energy’s released over a few hours whereas with a high explosive it’s released almost instantaneously.

“A typical blast load we would measure is the equivalent pressure of the population of Sheffield standing on a dinner plate.

The picturesque setting for the Blast and Impact Research Group's base near Buxton (Blast and Impact Research Group/University of Sheffield)

"That pressure is applied and removed in about a thousandth of the blink of an eye.

"It’s pushing the extremes in both directions, which is a very interesting challenge from an experimental perspective.

"You need something sensitive enough to measure changes in millimetres and microseconds but rigid enough to withstand extremely high pressures.”

Dr Rigby and his colleagues take refuge in a concrete bunker during the explosions, but despite wearing ear plugs and ear defenders they can still hear the deafening sonic boom which is created.

In January, the university announced it had secured £1.3 million of government funding to build a new laboratory in which to conduct explosive, fragment and ballistic tests.

It will include a reinforced concrete blast chamber capable of withstanding a 1kg explosive internal blast, and will be equipped with ultra-high speed cameras, thermal imaging and flash x-ray to show how materials respond internally to an explosion.

The investment will help the team examine the impact of explosives on cities in various scenarios, ensuring buildings at the greatest risk of a terrorist attack can be designed to minimise the threat to life should the worst happen.

It is the latest development for the group, which has been working with the MoD, Home Office and key UK defence sector companies for more than 35 years, playing a key role in the development of new solutions to protect UK armed forces in expeditionary or peace-keeping roles.

The team’s research doesn’t just relate to bombs – it can also help minimise the destruction caused by accidental blasts.

When a fire in Beirut ignited ammonium nitrate stockpiled in a dockside warehouse last August, it caused an explosion which tore through the Lebanese capital, killing over 200 people and injuring thousands more.

The Sheffield research group was among the first to analyse the extent of the explosion, concluding that it was one of the largest non-nuclear blasts in history, equivalent to between 500 and 1,100 tonnes of TNT, releasing enough energy in a matter of milliseconds to power around 100 homes for a year.

Its findings could help ensure buildings in such potentially hazardous locations are better designed to withstand such huge pressures in the event of a similar disaster.

As Dr Rigby puts it, ‘we’re the guys who set the exam questions’, providing the data about blasts so others can answer the challenge of designing buildings to best withstand those destructive forces and protect any occupants in a worst-case scenario.