The term Ground Penetrating Radar (GPR Survey) can refer to either a device or technique used to explore underground. It is a comprehensive and non-destructive (NDT) surveying method that uses radio waves to map underground or ‘subsurface’ information. These electromagnetic waves can identify natural and man-made structures under the surface of the ground.
A GPR device is made of three important parts:
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Control unit
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Antenna
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Power Supply (Depending on the specific device used, the power source can be from batteries or an external power source such as a mains supply)
How Does a Ground Penetrating Radar Work?
A Ground Penetrating Radar works by emitting a pulse into the ground and recording the echoes that result from finding underground objects. Usually, they emit pulses of electromagnetic energy in the 1 to 1000 MHz frequency range. The control unit is an electronic system that generates the pulse of energy and the antenna sends the pulse under the surface of the ground.
When the antenna receives the electric pulse from the control unit it amplifies it and directs it underground. The stronger the pulse, the further underground it can go, and the smaller the objects it can identify. The higher the frequency the more accurate the survey so a high-quality antenna is incredibly important. When a pulse runs into underground objects it will create echoes. These echoes can be measured and used to determine the location of the object and the material it is made from.
The GDR’s control unit contains a computer hard drive which stores then data. Some devices can be attached to a laptop allowing the data to be viewed in live time, others require that the user downloads the data onto a laptop or computer once the survey has been completed.
This method can be used to identify many materials under the surface of the ground including but not limited to; concrete, plastic, PVC, metal, wood, glass, gemstones, water, and other naturally occurring matter.
The system will work best when it identifies an object which significantly differs from its surrounding, for example, a metal plate deep within the soil.
GPR can be used to detect things like:
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Pipes
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Geological features
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Air pockets
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Phone lines
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Previously excavated areas
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General rock or concrete obstructions
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Defects in-ground structure
Ground-penetrating radars can, therefore, save a lot of time effort and money when it comes to building or excavations projects.
The Advantages of using a Ground Penetrating Radar
The many advantages of using GPR’S to explore underground include:
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It is safe to use in public spaces.
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It is not destructive or intrusive meaning there is not, clearing up after the survey.
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It can be used to detect a wide variety of objects as well as water and holes in the earth.
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It can provide accurate estimations of the depth and size of objects.
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It is a quick method, high resolution data can be analyzed in real-time.
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It is more effective than other techniques such as infrared ultrasonic or microwave.
Summary
The use of ground-penetrating radars to survey underground is both cost-effective and non-disruptive. It offers a rapid means of obtaining underground information in a manner that is safer and more detailed than other survey methods available.
