GPR detection, or GPR survey, has been around for a very long time. Today, this technique has become an essential tool for construction workers. GPR survey is highly efficient for locating pipes, thus ensuring the safety of the workers and avoiding contact with other elements buried in the ground. GPR has also become an indispensable tool for locating objects that are difficult to identify in the ground.
What is GPR?
Ground-penetrating radar is used in many areas to observe man-made and natural features. GPR can detect underground tanks, metallic and non-metallic pipes, power lines, underground conduits such as water pipes, rebar and post-tensioning cables inside concrete.
Ground-penetrating radar waves are equal to those of a cell phone or Wi-Fi network, while X-rays, for safety reasons, require a clearance of 50 feet before being used. In general, ground-penetrating radar is the most cost-effective option and the fastest method of testing concrete.
The principle of using radio waves to determine internal soil structures has long been known. Among the earliest works in this field, the use of radio echo sounders to determine the thickness of ice sheets in Antarctica and the Arctic and to measure the thickness of glaciers is undoubtedly the most successful. GPR detection in non-glaciated areas was initiated in the early 1970s. The first achievements focused on work on permafrost soils.
What is the purpose of GPR?
Ground-penetrating radar is a safe, non-disruptive method that is the best way to examine the subsurface in a wide range of applications. GPR is easy to deploy in the field and sites can be scanned quickly, making it an economical choice as well. Originally introduced as a non-destructive technique for geophysical research, ground-penetrating radar provides information about the subsurface and allows for the detection and mapping of natural geological features and buried human infrastructure in a non-destructive manner.
Where can we use the GPR?
Ground-penetrating radar detection is currently a very effective method for locating and analyzing objects in the ground. This method is also used for many purposes such as:
Concrete scanning: GPR detection is mainly used to reinforce and identify steel in concrete. GPR can locate electrical cables and conduits. In addition, ground-penetrating radar detection is useful for testing the integrity of concrete and detecting voids in a soil foundation. This technique is totally non-invasive and presents no risk to workers or structures.
Archaeology: GPR is very useful for locating an area. It can also identify unrecorded graves and cultural data on maps.
Environment: GPR can be very useful in delineating contamination or saturation levels, landfill boundaries, and locating tanks located underground.
Detection of public underground infrastructures: It is very important to locate public underground infrastructures such as conduits, cables, pipes, fiber optic lines, elements of any kind, valves, water tanks, and many other objects.
Signal sampling techniques
Analog signals from the antenna must be sampled by the GPR and digitized for processing and display. The sampling technique, as well as the frequency at which samples are taken, can have a significant effect on the quality of the results. The sampling frequency is therefore a critical specification that helps determine the performance of the system.
In the past, GPR has used a technique called “equivalent time sampling”, which requires that a new pulse be sent from the transmitting antenna as each sample is recorded at the receiving end. This method is often referred to as conventional GPR.
However, modern elements can be used with a technique called real time sampling, or RTS. This method, as the name implies, captures the “real” signal directly and, unlike other systems, does not require repeating the transmit-and-record cycle. As a result, this GPR system can collect data thousands of times faster than a conventional system.
Ground-penetrating radar data processing
GPR data processing allows the raw data (collected and recorded on site) to be managed and reviewed using software on a computer. GPR data processing can facilitate the interpretation and analysis of the results.
It is often more efficient to post-process GPR data than to try to mark and make decisions immediately on site. Site complexity, operator experience, and project time challenges can all contribute to this approach. In general, post-processed information is more accurate and provides additional information to make important decisions.
Conclusion
GPR appeared a long time ago and has continued to evolve over time to the point of becoming an essential tool in the field of archaeology, construction, environment, etc. Thanks to this invention, users can identify all types of underground elements while ensuring the safety of people and workers. This technology will continue to develop over time and that is why many companies specialize in concrete slab scanning. Call us now and save time, money, and protect your employees.