From settlement to sinkholes, voids can cause a major problem on any site. Not only can they affect your design, budget and programme, but they could also result in major injury.
Whether siting a crane, erecting scaffolding, or simply working on a site, if voids are present, it’s essential that you know about them before starting work or bringing any heavy equipment onto site.
Underground voids can be associated with a whole array of features; from natural causes, such as sink holes and sea water ingress, to leaking pipes, and structural voids such as burials and basements. Similarly, voids in walls can be caused by issues such as chimney flues and structural delamination.
The Answer - A Ground Penetrating Radar (GPR) Survey
GPR is an ideal technique to locate voids. The large electrical contrast between solid materials and air generates a high amplitude response, which should stand out clearly against the background reflections. Voids create a characteristic strong response with an area of ringing, to help us identify voids before they manifest themselves at the surface.
Above: GPR Radargrams (section views) showing voids at 1m depth caused by water ingress along a stretch of promenade.
High Frequency GPR
SUMO Services have a range of GPR antennae to help find voids in a variety of conditions. Our high frequency antennas (1.2GHz – 2GHz) allows the signal to see up to 50cm to small voids caused by structural delamination and chimney flues.
Above – Interpretation of GPR data showing location of chimney flues on a wall.
Dual Frequency GPR
While our Dual Frequency GPR system is ideal for carriageways, hardstanding or even burial grounds. By providing both 300 and 800MHz antennas, it allows a high resolution, shallow survey (c.1m) at the same time as a deeper, lower resolution survey (c2.5m) to help locate a wide range of voids within many different environments.
Above - Dual Frequency GPR Survey and Timeslice plot (plan view) showing two area of voiding highlighted in orange.
Single Frequency GPR
Finally, SUMO have a variety of single frequency antennas for specialist applications. We have utilised these antennae in a range of applications from flood defences, harbour walls and water reservoir slipways.
Above – antennas in all shapes and sizes - 1500MHz antenna, 400MHz antenna and 200MHz antenna.
With a wide range of GPR equipment and a vast wealth of experience, SUMO are here to help you avoid any hidden dangers on your site.
Want to learn more?
Please pick up the phone and speak to Simon Haddrell or Richard Fleming on
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