Ground-penetrating radar, more commonly referred to as GPR, is a form of subsurface imaging that’s used to detect underground objects or voids.
GPR has become a go-to tool with applications in a wide array of industries because of it's non-invasive and cost-effective nature.
However to fully understand the benefits of GPR we think that it's important for you to have an understanding of how it works!
Ground-penetrating radar creates comprehensive subsurface images by transmitting electromagnetic energy into the ground that's being Surveyed to detect objects, voids and anomalies.
The GPR unit sends out pulses of waves in the microwave band.
These pulses penetrate into the ground and are reflected, refracted or scattered when they encounter a change in material under the ground. This is then indicating that there is an object or another type of anomaly.
The strength of this reflection, known as its amplitude, depends on the contrast in conductivities between the materials the signal passes through, and how the impulse reacts is primarily determined by the object’s density and size.
This altered signal is then picked up by the GPR unit’s receiver, where it’s recorded along with its two-way travel time. The amplitude, travel time and relative permittivity of the subsurface materials are combined to create a depth scale for the scan.
Then Using the Specialised GPR software our Technicians can then
interpret the images that are created by the software from the raw data captured. The data is transformed into black and white static images where abnormalities can be identified.
Now that you Understand how GPR works, Let's get into the Benefits of it!
GPR has become the technology of choice for industries that need to know more about what lies underground. GPR is cost-effective enough for regular use, and because the technology is noninvasive and safe to use, it’s ideal for surveys involving public locations, interior spaces or landscaped areas without causing mass disruption to day-to-day operations. Its main benefits include its ease of execution, varied detection capabilities and wide array of applications.
Ease of Use
One of GPR’s main advantages is it's ease of use.
With a single piece of equipment and a trained operator, GPR can be used to survey a large area in a small amount of time.
To begin the imaging, the GPR operator passes the unit over the target location, following consecutive survey lines. As the device moves across the area, an onboard transmitter sends pulses of electromagnetic energy into the ground.
If the ping encounters an object or anomaly, the signal is reflected, refracted and scattered, depending on the object’s density. The unit’s receiver registers and records the returning signal.
Using a series of consecutive scans, the GPR Technician can obtain comprehensive data from the targeted area. Onboard software then translates this data into a digital image, providing a map of underground structures, voids and other anomalies.
Because the actual imaging typically looks like either black and white static or colorful bands, with anomalies represented by hyperbolas, data must be interpreted by trained GPR technicians before it’s usable.
However, this can easily be done in real time, letting us flag areas of interest or concern immediately, Letting us get the information needed to the appropiate parties ASAP.
Plus, because GPR units are small and often portable, they can easily scan hard-to-reach areas.
Detection Capabilities
Generally, GPR can identify anomalies, including voids, in soil, rock and concrete. It can locate metal and nonmetal objects, and it may also detect differences in the composition of the ground.
GPR is capable of detecting the following materials:
Clay
Concrete
Metal
Plastic
PVC
Water
Wood
Ground-penetrating radar can also alert the technician to recent changes in the soil condition caused by digging or the intrusion of foreign material.
Plus, because different frequencies may be used when scanning, GPR pulses can penetrate to varying depths and may be adapted to the composition of the ground.
GPR may also be used for concrete scanning, and handheld units can scan vertical surfaces or ceilings.
GPR scans can typically provide the depth and thickness of subsurface anomalies.
They also have GPS and mapping integration capabilities so they can deliver an accurate visual map of the target area, which includes coordinates that correlate to areas of interest.
When do we use GPR?
At AHC Construction we typically use GPR in stores to identify any services that may be in the ground such as utilities for fridges when working in stores such as Tesco's or on new sites to locate changes in the grounds surface and to find hidden utilities such as cables and drainage.
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