Ground Penetrating Radar

Ground penetrating radar (GPR) uses a transmitting antenna to send pulses of electromagnetic energy into the ground. The pulses travel through the ground and subsurface materials and reflect off objects with different dielectric or conductive properties. These signal reflections are displayed on a receiver screen as distortions and contrasts of the original signal. Read more :

By analyzing these differences in the signals, GPR operators can determine the type and location of subsurface objects. In addition, they can detect voids in the ground by examining the number of times a signal is reflected at a void-containing interface.

Understanding the Principles of Ground Penetrating Radar

GPR has a wide variety of applications that benefit construction, public safety, and environmental sectors. These include locating underground pipes and utilities, including telecommunications lines, gas & oil pipelines and electrical conduit. It can also locate rebar and other structural elements within concrete. It’s non-intrusive, harmless and quick, making it an ideal technique to support visual inspection. GPR and digital scanning and evaluation technology (DSET) are commonly used in conjunction to support inspections of bridge decks.

While GPR offers a great deal of utility, there are some conditions and features that make it unsuitable for certain environments. For instance, a dense clay soil or water with high mineral content attenuates the electromagnetic wave and reduces penetration depth. This is not a problem for de-ionised water and sand, but it is a concern in areas with heavy clay or stone. Ground penetrating radar can also be hampered by the presence of metallic objects, including very dense reinforcement.

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