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GEOPHYSICAL
ENGINEERING

Air Voids

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From settlement to sinkholes, voids can cause a major problem on any site. Not only could theyaffect your design, budget and programme, but they could 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.

Air voids can be associated with a whole array of features; from natural causes, such as sink holes and sea water ingress, to leaking pipes, below ground structural voids such as burials and basements, and voids in walls caused by chimneys flues and structural delamination.

 

The Answer – A GPR Survey (but it all depends on the size and scale of the voids)

 

Ground Penetrating Radar (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 the manifest themselves at the surface.

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Above : GPR Radargrams (sectionn 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 penetrate to 50cm to locate small voids caused by structural delamination and chimney flues.

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Above : Interpretation of GPR data showing location of chimney flues on a wall

 

Dual Frequency GPR

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 (c.2.5m) to help locate a wide range of voids within many different environments.

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Above : Dual Frequency GPR Survey and Timeslice plot (plan view) showing two areas of voiding highlighted in orange.

 

Single Frequency GPR

 

Finally, SUMO have access to a range 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.

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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. If you have any questions.

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FREE SURVEY QUOTATION

 

Receive a FREE Survey quotation from one of our survey engineers?

 

Chat through any requirements you need, including site survey, survey methodologies and detail requirements.

Geophysical Engineering Surveys
 

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Air Raid Shelters

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Cellars & Basements

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Post Tension Cables

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Underground Storage Tanks

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Air Voids

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Chimney Flues

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Rebar

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Water Engineering

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Badger Setts

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Earthing Installations

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Sinkholes

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Burials

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Geological Application

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Soil Thermal Resistivity Testing

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Buried Foundations

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Landfills

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Structural Investigations

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Buried Manholes

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Mineshafts

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Tree Roots

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