Ground Penetrating Radar (GPR) is a non-destructive detection and imaging method which identifies subsurface elements either underground or within a surface such as concrete.
This technology employs radio waves to map structures and features buried in the ground or encased within concrete. It provides a profile of subsurface features, which can be used to determine the location of buried objects.
How does it work?
GPR operates by transmitting pulses of high-frequency radio waves, in the range of 10Mhz-2.6GHz, down into the ground through a transducer (also known as an antenna).
As the radio waves encounter discontinuities, they reflect back to the surface. These reflections, or "bounces" are received by the antenna, and the data is shown on a readout as a series of hyperbolas. These hyperbolas vary in size, definition, and color depending on what type of object was located. A qualified GPR technician, like a GPRS SIM-certified Project Manager, can interpret this data to determine what was found and the precise location of the objects.
What can GPR find?
GPR can find anything that has contact within the surrounding soil. This includes both metallic and non-metallic objects.
A PVC pipe and the air inside of it, for example, have a different composition than the dirt that surrounds it. Similarly, voids and backfilled excavations will also have contrast from the surrounding soil.
GPR can locate utility lines, structural supports such as rebar and post tension cables, and environmental objects including underground storage tanks (USTs).
How Accurate is it?
GPR's unparalleled accuracy has made it the industry-leading option for utility locating and precision concrete scanning.
Ground and soil conditions, weather, and type of material located are a few of the potential limiting factors for GPR. For example, GPR does not penetrate clay soil well due to the amount of moisture present.
An experienced GPR technician will be able to assess your site to determine if GPR is the right tool for the job.
What are its advantages and disadvantages?
The main advantages of the method are:
- It is non-destructive
- It is fast (hundreds of measurements captured per second)
- It can detect both metallic and non-metallic materials
- It provides superior resolution and reliability
- It is cost effective
The main disadvantages are:
- Proper use of GPR requires significant training
- Results can be affected by the moisture content and specific materials comprising the ground.
- GPR cannot tell the composition of a target. It can only tell if there is a contrast between the target and the surrounding area. Water reflects the signals differently from materials in the ground, which can mask the presence of utility lines
With over 400 GPRS Project Managers stationed in every major market across the United States, you can be sure that there are quality GPR scanning services near you. GPRS provides a host of infrastructure visualization services to help you locate and evaluate your utilities and other subsurface structures.
What can we help you visualize? Click here to schedule a service today.
Note: GPRS does not provide geophysical, geological, land surveying or engineering services. If you need such services, please contact an appropriate professional.
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