Ground Penetrating Radar
What Is A Ground Penetrating Radar?
The ground-penetrating radar makes use of radiofrequency waves to create in-depth subsurface images that give us the direct location of underground utilities, UST’s and numerous other anomalies. In essence, the GPR is better known for employing the state-of-the-art geophysical locating method and is often used by SoftDig. When compared to others, this is one of the few nondestructive methods that use radio frequencies within the typical microwave band. The GPR detects the reflected signals that have already made contact with subsurface structures and others.
What Can You Use A GPR For?
GPR applications are usually conducted in a variety of media. These include rock, pavements, soil, and numerous other structures. SoftDig makes use of the single-frequency variant as they detect utility lines as deep as 10 ft. In the case of congested areas, multi-frequency 3D GPRs are used.
Additionally, high-frequency radars are specially designed for concrete usage. Hence, they are used for inspecting the structural elements within wall slabs and concrete floors that range up to 20 inches. Lastly, UST Investigations are mainly used for examining geological structures.
Understanding How The GPR Works
The full line of GPR units from SoftDig uses a transmitter to emit radio waves. Deep inspections are carried out with the lower end of 250 MHz and shallower concrete slabs are inspected with waves of 1.6 GHz. When the waves hit either boundary material or a buried object, they are then refracted, reflected, or scattered as they return to the surface.
The GPR has a receiving antenna that detects and records the changes in the return signal. The principles applied to the GPR are quite similar to that of seismology. However, the GPR runs on electromagnetic energy whereas acoustic energy is used for seismology.
Whenever energy is reflected, a series of subsurface electrical properties usually chance. In the case of seismic energy, the mechanical properties of the subsurface tend to change. While the GPR is effective, it is geared to certain conditions only.
When the GPR comes into contact with high salt content like that of coastal areas, utilities can almost never be found. This is because rocks and tightly packed clays prevent them from being seen by the radar.
Why Should You Use SoftDig For Your GPR Services?
Thus far, SoftDig has carried out thousands of GPR investigations successfully and they have continued to exceed the highest industry standards. SoftDig ranks at the top for professionalism, integrity, and extreme accuracy. At SoftDig, we’ve used our expert knowledge of GPR on a broader spectrum of fields. We’ve also worked on a series of high-profile jobs and delivered the best results.
What Is Detected By The GPR?
As previously mentioned, the Ground Penetrating Radar can be used to find several different structures and items. The GPR is known for being most effective when there’s a larger difference present in the targets electromagnetic property. However, the GPR is used to locate items constructed with the following materials:
Services And GPR Application
*Underground Storage Tank Delineation (UST)
*Utility Mapping And Locating Of Both Metallic And Non-Metallic Objects
*Rebar Mapping And Thickness Verification of concrete
*Well, Septic system (leach field and tanks), pipe and cistern locating
*Deficiency Identification of Structural Elements (corrosion, voids, rebar wear, and sub-base settlements)
*Mapping Of Cemetry Graves
*Locating Leaking Pipeline
*Determining The Thickness Of Paving Materials
*Environmental Issues (overburden thickness, drum piles, landfill boundaries, historic fills)
*Delineation Of Archeological Features (roadbeds, wells, foundations, and privies)
*Ahead Of Coring Mark-Out Of Construction Embedments And Elements
*Detection Of Geological Features (karst, roadbeds, foundations, wells, privies)
Advantages Of The Ground Penetrating Radar
Unlike other methods of surveying, the GPR is completely non-invasive and cost-effective. The GPR produces some of the most important information needed before workers can start excavating and breaking the ground under them. The following are some of the main advantages that come with the GPR:
*Safe for use in public spaces and other project sites.
*Can detect non-metal and metal objects along with voids and other irregularities underground.
*A targets depth, thickness, and full-dimension can be measured.
*Large site areas are covered quickly since data is generated faster than other methods.
*Data is generated with only one side of a surface being scanned.
*Different frequencies can be used to suit different depths and resolutions.
*Less expensive when compared to other methods of surveying.
*No ground disturbance, digging or excavating is required. Hence, lawns and other landscaping structures are left undisturbed.
*Data collected can be used at any point during a job.
1) Can a ground-penetrating radar be used to determine the size of a void cavity underground?
At SoftDig, our team can easily pinpoint voids and determine their boundaries as well. However, the depth of a void cannot be identified with the use of a GPR.
2) Can a GPR be used to scan ceilings and surfaces?
Yes, the GPR can be used in this way. As such, identification of rebars in walls and columns are located.
3) How does the GPR unit work?
The unit’s antenna generates energy pulses that are sent into different materials. A computer is used to record the energy and time it takes for the pulse to return. Reflections are created by variations in the materials found in the subsurface. The computer detects and determines what the reflections mean; these are caused by wires, pipes, and others.
4) How deep do the waves of the GPR go to find targets?
The target material determines the antenna frequency being used for the job. Lower frequencies are used for deeper depths but will reduce the resolution quality. So if you’re working in dry conditions, you’re likely to receive better resolutions than that of heavier soil conditions.
5) Can the GPR be used in water?
The GPR can be used in water. However, it works in freshwater and not saltwater.
6) Can I use my mobile phone when working around/with GPR units and equipment?
Since the GPR uses electromagnetic energy over a wider band, it is recommended that your mobile be turned off. This is suggested due to the fact that mobiles transmit the same type of energy and it can hamper the results of your survey. However, if you are required to leave your mobile on, be sure that its at least 10 to 20 feet from the GPR’s antenna.