Void and cavity location and scanning
Void and cavity location with Geophysics requires experience, a good understanding of the targets and a systematic approach Download Application Notes
This is an example of a class A RVS. The reader can see the negative or “black” pulse at the top of the target and the weaker but evident positive reflection at the base of this target.
Subsurface Imaging in action locating voids under concrete slabs

Extensive test boring had shown some cavities but it was much quicker and easier to do GPR.

Setting up this grids over the probable cavities
The NDT methods to locate the cavities meant quick results , no drilling and precise location of the problem areas.

Collecting the data
In addition this also meant the survey can be rerun to check void development over a longer interval.

Checking the layout
The output is from the survey in the pictures. It is a fine grid of data where the Ground Radar lines are run in two directions at right angles with a spacing of 0.5 m. Processing involves combining all these together. The output is a horizontal slice to give plan view images that are hereThe result… The red and yellow areas are the voids.. The green shows no voids. These were checked by lifting test slabs to check and the correlations were within cm for the void edges Plan View of GPR data
Download Application Notes SUCCESS
We have achieved similar results with a variety of geophysical methods, Radar, EM, Electrical Resistivity Imaging, Cross-hole surveysTalk to SSI about your void imaging or location issue email orPhone

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