29 April 2020

Advances in our understanding of buried blasts

The Department of Civil & Structural Engineering’s latest paper is the culmination of their research into the behaviour of buried explosives and provides invaluable understanding that could save lives in combat and post-conflict zones.

CIV Sam paper

The Blast & Impact research group in the department have spent the last decade investigating a vital gap in knowledge about how buried explosives interact with their surrounding environment. This is a key factor in determining the pattern and extent of the damage produced by a buried explosive.

In a paper published in the Proceedings of the Royal Society, Dr Sam Clarke and his team have provided the most detailed experimental dataset that informs us how the detonation of buried charges is affected by the kind of material they’re buried in.  Due to the use of shallow-buried improvised explosive devices in modern conflict zones, there is an increased need for the scientific community to understand the mechanisms that influence the ejecta as it leaves the ground and hits a target.

Armoured vehicle explosive testing (Defence Science and Technology Laboratory)

They found that the output of a blast is worsened by the fact that it is buried; after detonation, a high pressure wave travels into the surrounding soil, compacting the material as it propagates. The soil surrounding an explosion serves to direct the detonation upwards and the soil above serves to focus the loading, and contributes an additional momentum transfer.

The energy released by the blast wave is dependent on the properties of the soil and therefore it differs with different types of soil. It was also discovered that an increase in the moisture content of the soil significantly increases the load by creating a ‘ring of fire’ around the explosive gasses that are emitted.

CIV Sam paper

Detonations of explosives in buried in soils are extremely complex events that involve the interaction of shock waves with the surrounding soil, air and water. The understanding we’ve generated will play a key role in protecting people and vehicles from buried explosive devices.”

Dr Sam Clarke

Experiments were performed using the Characterisation of Blast Loading apparatus, which consists of an array of Hopkinson pressure bars, housed at the University of Sheffield Blast & Impact Laboratory.

The data will be used to contribute to a wider need to understand the effects of IEDs and land mines. As well as helping to inform future designs of armoured vehicles and personal armour, for example, the data produced by the project will aid risk assessment and route planning for operations in current and future combat zones.

This work was funded by the Defence Science and Technology Laboratory (Dstl) and by the Understanding the Role of Soil in Subsurface Explosive Events project, EPSRC grant no. EP/L011441/1.

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