Abstract
Ground penetrating radar (GPR) has evolved into an effective, non-destructive geophysical method for detecting subsurface features in a variety of fields, particularly geology, engineering ', hydrogeology, and archaeology. GPR emits a pulse of electromagnetic energy into the subsurface where it is reflected back and recorded. The velocity, attenuation, and strength of the radar energy are affected by the electrical properties of a material, namely electric permittivity. The presence of water, whose relative electric permittivity is high (&,=8 1), will cause the relative electric pen-permittivity of soils and rocks to increase. A contrast in electric pen-permittivity between two media gives rise to a reflection in the radar profile. Ground penetrating radar has been widely used 'in a variety of geologic environments achieving good results. However, the geologic studies conducted in this research did not meet expectations, namely in the amount of depth penetration by the radar. Despite studies conducted prior to the acquisition of the radar data, a depth only on the order of a few meters was reached. Ground penetrating radar was successful in mapping subsurface targets for engineering studies. Metal objects act as perfect reflectors to radar waves, making underground storage tanksand metal pipes easy to detect with GPR. These point-like objects 'yield hyperbolic reflections within the radar profile. Gypsum sinkholes compromising the stability of nearby roadways were located using ground penetrating radar. Some sinkholes reached just below the surface. GPR also successfully mapped the boundary of water saturation in a media underlying a roadway. Future engineering decisions regarding each site will be based on the results of these studies.
Servos, Stacia Lynn (1998). Assessing the capabilities of ground penetrating radar for applications in geologic and engineering subsurface studies. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1998 -THESIS -S47.