Ground-penetrating radar is a method of underground mapping that uses electromagnetic waves to determine the formation and composition of the subsoil. This article explains how to use ground-penetrating radar and how to correctly interpret the results obtained, as well as the benefits associated with it.
What Is Ground Penetrating Radar (GPR)?
Ground-penetrating, or GPR, is used in many industries to observe artificial and natural features. Ground penetrating radar can detect underground reservoirs, metallic and non-metallic pipes, power lines, underground lines such as water pipes, as well as fittings and tension cables inside concrete.
Radar waves entering the ground are equivalent to mobile phone or Wi-Fi waves, while X-rays require a distance of 50 feet before use for safety reasons. In general, ground-penetrating radar is the most cost-effective option and the fastest method for testing concrete.
The principle of using radio waves to determine the earth’s internal structures has long been known. Among the first studies carried out in this area, the use of radiosounders to determine the thickness of Antarctic and Arctic ice sheets and to measure the thickness of glaciers is probably the most complete. GPR detection in non-glacial locations began in the early 1970s. Early successes focused on work on permafrost soils.
Methods Used for the Detection of Underground Reservoirs
Electromagnetic conductivity: This method of detecting underground pipes can be used to calculate the conductivity of the ground and to detect underground reservoirs or metal infrastructure buried in the ground, such as power line pins and concrete pipes.
Cable Locators: These locators are designed to locate electrical and telephone cables. These instruments use high or low frequencies to detect underground lines over very long distances.
Tree Locators: These tree locators can be used to locate metal hatches. These tools can also reveal hatches hidden in the ground.
Ground-penetrating radar: Ground-penetrating radar is an instrument that uses multiple frequencies to acquire data at different depth levels. However, the main detection frequency of the underground line is 400 MHz. GPR is also used to identify the depth and size of public utilities. It is a very effective tool in sandy soils but not suitable for clay soils.
Aspiration or Hydro Excavation: Aspiration excavation remains a fast and non-destructive method for locating and discovering underground infrastructure. In this method, high-pressure air is used to disturb the soil, which is then sucked in. This method is also called soft digging.
Frequency locators: These locators play an essential role in locating distribution networks or detecting underground reservoirs. They can be used to locate the energy emitted by telephone cables, electrical wires and optical fibers buried in the ground. Generally, to increase the signal received by the frequency locator, technicians attach a high-frequency transmitter, such as an electrical tool.
Magnetometers: Magnetometers are instruments capable of locating ferrous metal devices or ferrous objects buried in the ground. In addition, they have the ability to locate deep infrastructure and the sensitivity of these magnetometers is generally very high.
Advantages of Ground Penetrating Radar Detection
Increased safety in the workplace
Ground-penetrating radar detection can be used to locate sewer, water, steam, storm, oil, gas and electrical cables. When used, ground-penetrating radar detection can help workers and utilities avoid accidental collisions. Consequently, ground penetrating radar detection contributes to ensuring safety at the construction site.
GPR detection is accurate
GPR detection provides accurate images and, thanks to its ability to analyze sections at different depths, allows the depth and orientation of buried objects to be known. Dual-tech systems that combine ground-penetrating radar and power-line detection systems go even further to indicate which lines contain dangerous power lines.
Difficult places
GPR sensors are small and can be used in confined spaces and in any orientation on floors, walls and ceilings. Ground penetrating radar is applied from an exposed surface and is capable of finding characteristics in ground slabs. It can even identify voids in surrounding materials. Large areas can be mapped effectively by deploying a GPR sensor on a truck or platform towed by a vehicle.
GPR is effective
Although demand for these services is increasing, the funds available to pay for them are difficult to find. Having the ability and reputation to do meticulous work without repeated visits or mistakes is a real competitive advantage. Speed is good, efficiency is better. A professional technician can provide this advantage. Contractors need to adapt their efforts to site conditions and conduct exploratory analysis to decide where and if further analysis is needed.
Non-invasive
It is always better to conduct assessments and tests without resorting to costly and harmful destructive tests. Even if destructive tests are needed, conducting them where they are most effective saves time and money.