Detection of man-made voids by 2D & 3D geoelectrical imaging surveys

Abstract

The geoelectrical imaging technique has been widely used for environmental and engineering studies in recent years as this technique gives a graphic representation of the distribution of electrical properties in the subsurface. The evaluation of subsurface objects and detection of buried utilities, such as pipes, is of particular interest for a variety of engineering and environmental applications. The geoelectrical imaging technique as a non-destructive and inexpensive tool for mapping buried objects was successfully used to locate an underground metal pipe with a diameter of 1.20 m buried at a depth of 0.9 m in the Universiti Sains Malaysia campus. The 2D and 3D geoelectrical imaging surveys using the Wenner, Pole-Pole, Pole-Dipole and Wenner-Schlumberger electrode arrays successfully mapped the shape and location of the underground pipe.The 2D resistivity sections as well as the 3D vertical slice sections from these surveys demonstrate the effective of the improvements made in field data acquisition that has partially suppressed the effects of a variety of electrical noise sources surrounding the surveyed area. It has reduced the effects of such electrical noise on the field measurements, and has enabled the field results to be more representative of the subsurface target. Moreover it has strengthened the current signal and thus improved the voltage-to-noise ratio for the different electrode arrays used in these surveys.