Ground penetrating radar in geotechnical applications

Abstract

Ground probing radar (GPR) is a relatively new geophysical technique that has evolved from radio-frequency soundings of ice to determine depth to bed rock. The technique attracted interest as a viable geophysical tool in the early 1970s when a number of successful experiments were reported by researchers including Cook (1974, 75) and Morey (1974). The Geomechanics Division of CSIRO has been carrying out field investigations with GPR since suitable equipment was obtained in 1986. The Division's experience with GPR in a wide variety of sites and geological conditions has clearly shown that the radar method is capable of generating valuable information concerning shallow subsurface structure although the technique has been found to be highly site-dependent with depths of penetration rarely exceeding 10 m. Consequently the role of GPR in exploration is limited. It is best suited to geotechnical or engineering geophysics applications such as the detection underground services and cavities, foundation studies and the detection of the water table at shallow depths in sandy soils. Despite these limitations, GPR is capable of producing high quality data. These data can be processed with the use of seismic-style filters and migraion schemes to yield accurate images of subsurface structure.