Additional Information
Applications
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Ground Penetrating Radar
Ground Penetrating Radar (GPR) is perhaps the most effective geophysical tool available to engineers and earth scientists because it provides real-time graphic images of the subsurface and virtually anything buried in it. The device is typically used “on-the-fly” to cover large areas to instantly locate a broad range of both man-made and naturally occurring subsurface features. GPR has become the most diverse geophysical technique currently available to engineering and environmental professionals. When soil conditions are favorable, it is a very effective tool for locating man-made targets like pipelines, buried utility infrastructure, unexploded ordinance (UXO), and is equally effective on natural features such as stratigraphic geology, the water table, voids and fractures.
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GPR Environmental Site Characterization
This GPR image was used to identify the location of a manmade trench or subsidence zone as a potential pathway for the migration of contaminants. |
Typical, proven applications include:
- mapping buried utilities and pipes
- determining fill thickness
- mapping geologic stratigraphy
- mapping aquifers, aquicludes
- locating voids, shallow bedrock units, and fractures
- archaeology
- map shallow mine tunnels/caves
- forensics
- map extent of certain contaminant plumes
- site hazard clearance for trenching and drilling
- unexploded ordinance (UXO)
- locating underground storage tanks, drums
- image rebar in concrete
- brick, masonry and concrete integrity testing
- marine sub-bottom profiling in lakes, rivers
The GPR instrument uses pulsed radio frequency (RF) energy to bounce signals off buried man-made objects and naturally occurring interfaces. The signals are reflected by contrasts in the dielectric properties, conductivity and magnetic permeability of targets within the host material. Units are usually cart-mounted, consisting of a recorder mounted on the handlebar an antenna assembly very close to or actually coupled the ground. The antenna assembly typically consists of a bow-tie transmitter and receiver. Different antennae operating at frequencies ranging from 25 MHz to 2 GHz are selected according to the objective. The reflected signals return to a receiver creating a continuous graphic profile of the subsurface. Data is usually stored for optional post data processing and enhancement, and for producing hard copies for client reports.
GPR Rebar Survey
 High frequency (900 MHz – 1.5 GHz) Structure Scan radar antennas are used to map depth and spatial arrangement and uniformity of rebar in concrete structure. Identification of rebar in concrete is used to assess concrete integrity, and to determine boring locations in areas where rebar is not present. Structure Scan can also be used to locate fractures and thickness of concrete.
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