Public utility mapping serves to identify the location of buried cables or pipes. Not only is it an important part of the civil engineering process, but it can save time and money on expensive repair work and delays resulting from utility collisions. With the proper mapping method, such as ground penetrating radar detection, project managers can precisely estimate the work costs to be performed. In this article, the following questions will be answered:
What Is GPR?
Ground penetrating radar (GPR) is a common geophysical location method. This technology utilizes radio frequency waves to provide images of underground structures, which allows us to precisely locate buried utilities. The use of this non-destructive method is based on radio frequencies in the microwave band, which provide reflected signals from underground structures or changes in the subsurface composition.
How Does GPR Work?
GPR is based on energetic waves in the microwave band, whose frequency varies from 1 to 1000 MHz. Ground penetrating radar has two main components: a receiving antenna and a transmitter. The transmitter emits electromagnetic energy into the subsurface as well as other materials. GPR functions by sending a pulse into the soil and recording the echoes coming from buried objects. This equipment can also detect changes in the composition of the soil material.
When the electromagnetic pulse strikes an object, the object’s density reflects, refracts and scatters this signal. The receiver records variations and detects the returning signals within them. The GPR system is equipped with software that converts these signals into visual images of underground objects. In this way, it is used to map utilities and structures buried in the subsurface or in human-made structures.
What Are the Advantages of GPR?
Non-invasive method
Evaluation and testing is always best done without costly and damaging destructive testing. Even when expensive destructive testing or coring is required, targeting it where it is most effective saves time and money.
Saving money
Any kind of disruption can affect a project’s budget. If there are unexpected rocks or sewer material underground, it can massively impact the cost. Ground penetrating radar can provide savings by finding fiber optic lines before the project starts. GPR can also detect electrical lines buried under concrete to make sure there is zero downtime.
It can be applied in difficult sites
GPR sensors are small and can be used in tight spaces and in any orientation on floors, walls and ceilings. GPR is applied from the exposed surface and is able to locate features in slabs in the ground. It can even identify voids in surrounding materials. Large areas can be mapped efficiently by deploying the GPR sensor on a cart or vehicle-drawn platform.
Ground penetrating radar is easy to use
GPR was originally considered a large capital investment, reserved for skilled operators and experts. Through innovation and technological advances, modern GPR equipment has developed a basic and simple electronic design, with user-friendly interfaces requiring no complex settings of filters.
Increasing work site safety
One of the benefits of GPR detection is that it can be used to locate sewer lines, water, steam, storms, oil, gas, and electrical cables. When ground-penetrating radar detection is used, it can help workers and utilities avoid accidental collisions. Therefore, ground-penetrating radar detection helps to ensure safety on a construction site.
What Are the Disadvantages of GPR?
While this equipment has many advantages, there are also some disadvantages. Here are the disadvantages of ground penetrating radar:
- GPR takes time to collect data
- More intensive training is required
- Cannot determine the exact nature of a utility from a radargram splice
- The ground must be relatively flat to ensure optimal radar penetration
- Obstructions may reduce the coverage of the GPR scan
- Not effective in water-saturated areas, such as clay soils
- The interpretation of the data is dependent on the technician—so human error is a factor
- GPR data can take a long time to post-process
Applications of GPR
Cartography of tree roots: To understand the overall stability and health of a given tree, it’s essential to observe an understated root system. Trees growing in urban areas require careful maintenance and monitoring to allow them to thrive, while minimizing the risk to surrounding utilities.
Concrete scanning: GPR detection is used primarily to reinforce and identify steel in concrete. Ground penetrating radar can locate electrical cables and conduits. In addition, ground-penetrating radar scanning 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.
Lake and river profiling: Establishing the depth of water and river profiles offers useful information for informing lake bottom engineering design, calculating water volume and river flow. GPR can also be applied in environmental monitoring, engineering works, and scientific investigation.
Archaeology: Ground penetrating radar is very useful for locating areas. It can also identify unrecorded graves and cultural data on maps.
Public underground infrastructure detection: It is crucial to locate public underground infrastructures such as conduits, cables, pipes, fiber optic lines, elements of any kind, valves, water tanks and many other objects.
The environment: GPR can be extremely useful in delineating contamination or saturation levels, landfill boundaries, and locating underground tanks.
Conclusion
Ground penetrating radar 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, etc. Thanks to this invention, users can identify all types of underground elements while ensuring the safety of workers and other people. This technology will continue to develop over time, which is why many companies have chosen to specialize in concrete slab scanning. Contact us today to save time, money and protect your employees.