GPR is a non-intrusive and important part of many site investigations. Typically carried out to identify buried services prior to a careful evacuation, ground penetration radar can also be used to find sinkholes and features of karst geology.
But how does this investigative method work? And when is it most needed? The Borehole Solutions teams have put together this blog to explore this topic in a little more detail.
What Is Ground Penetration Radar?
Many will be surprised to hear that this technique is almost 100 years old, with the first radar technology dating back to the late nineteenth century. In 1926, Dr. Hülsenbeck patented his pulse radar system and with this, radar was used for the first time in a geotechnical setting. This technique sends pulses of energy into the ground that’s being investigated – but how… and why?
How Does GPR Work?
The ground penetration radar transmitter emits high-frequency radio waves into the ground below. Once these waves hit buried material, such as concrete, the pulse will be reflected, or else scattered, back up to the surface. The returned pulse and its particular characteristics are recorded by the receiver. These results will allow a comprehensive picture of the subsurface to be built up. The technique’s non-intrusiveness is, indisputably, its main advantage.
There are multiple features that GPR is used to locate, many of which will require the least intrusive method possible. The radar will frequently be used to locate utilities – such as fibre optic cables or gas works – under major arterial motorways, for example. It goes without saying that any work that needs doing here will have a major impact on the surrounding area due to road closures. Such a non-intrusive technique, however, significantly mitigates the ‘downtime’. Aside from this benefit, GPR is also considerably cheap in its operation.
What Can Ground Penetration Radar Identify?
Able to identify a wide variety of materials (or lack thereof), GPR will detect pretty much anything under the ground. It is able to do this due to its method of recording any changes in the subsurface environment. So, not only can it be used to identify buried materials, but voids too! This includes sinkholes and former coal workings, for example.
How Accurate Is GPR?
On the whole, ground penetration radar is an incredibly accurate method of surveying and mapping. It’s accuracy can vary depending on different factors, however, such as material composition and moisture content. Despite this, this century-old technique can be trusted to deliver reliable results.
Ground penetration radar is a technique that’s often overlooked in the geotechnical world. This is largely due to the fact that it gets the job done quietly and efficiently, leaving no trace. Not limited to geotechnical settings, GPR is also used in forensic and archaeological settings too!
If you would like to find out more about the range of site investigation services we offer at Borehole Solutions, please don’t hesitate to get in touch! You can contact us today on 01733 200 501.