Skip to main content

Ground Penetrating Radar (GPR)

The method is based on the input of short electromagnetic pulses at variable frequency, repeated continuously and emitted by an antenna placed near the surface to be investigated. When the propagating electromagnetic pulse encounters a surface that separates two media having different physical characteristics, a part of the incident energy is reflected, and a part continues in the second medium. The waves reflected from the discontinuity surface return to the surface and are detected by the receiving antenna, while the part of transmitted energy that proceeds beyond the discontinuity itself is available for further reflection on any deeper discontinuities.

Typically, pulsed EM energy is generated at predetermined station locations along the length of the GPR profile. The travel times and amplitudes of reflected EM energy are recorded by a transmitter–receiver. The recorded travel time–amplitude information is normally used to generate a GPR profile (2-D time–amplitude image). These data can be transformed into a 2-D velocity–depth model.

Modified from “Introduction to Geotechnical Geophysics – N. Anderson and N. Croxton, Circular – Number E-C130, October 2008”.

Ground Penetrating Radar is a very versatile system adaptable to many terrains/environments.

The main scope is to pass the GPR antenna (different frequencies for different applications) over the area of investigation. This can be achieved by using the antenna on its own, mounted on a cart and hand pushed, towed by a vehicle, or pulled via a rope by hand. The methods used can be numerous and decided upon on a project-to-project basis.

Figure 1: Detailed investigation (i.e., 0.5m line spacing) for concrete thickness mapping.

What are the most common uses of GPR scanning?

Utility location
Buried objects location
Landfill delineation
Underground void detection
Measuring slab thicknesses
Evaluating asphalt condition and thickness
Mapping archaeological sites
Concrete floor slab surveying
Locating buried obstructions
Pavement surveys
Rebar location and mapping
Mapping shallow geology and depth to bedrock

GPR FAQs

How long does it take to complete a GPR survey?

GPR is one of the fastest geophysical methodology available for any given application. However, the time required depends on size and complexity of the site, number of antennae/frequencies, and the density of the data required to achieve the scope of the project, e.g., GPR application can vary from concrete integrity using a hand-held antenna with 5cm grid spacing to road pavement inspection using a vehicle-towed antenna covering more than 50km in a day.

Are GPR surveys invasive?

No. GPR is one of the best Non-Destructive Testing (NDT) in the market and the most utilised system when a non-invasive survey is required.

How accurate is GPR?

GPR can be very accurate. However, data resolution can vary dramatically based on many aspects, e.g., required depth of investigation, geology, antenna frequency.

Where do we offer GPR surveys?

Scurbat can provide GPR survey anywhere in Australia and overseas. We carried out GPR surveys in many environments, from urban to desert, to mountain and farmland.

How much does a GPR survey cost?

As the applications for GPR are several, as well as the type of GPR systems/frequencies, it is difficult, and misleading, to provide an exact dollar value. A very indicative cost for the fieldwork component can vary from $1,500 to $4,500 per day. This excludes mobilisation and demobilisation, which can vary by 10s of thousands of dollars, e.g., urban Sydney or Kalumburu in the Kimberly? Also, it excludes processing and reporting, which depends on the amount of data acquired.

Reach Out and Let’s Discuss Your Project

No matter how simple or complex is your project, we can assist in many ways…a technical explanation? A practical field implementation? A budget discussion? Or a full project planning and execution? Just ask away.