Testing Of Resistivity Imaging Method with Different Protocols to Detect Void Using Miniature Model

Sinkholes, cavities, boulders and faults in rock and soil could lead to major engineering and environmental problems. Resistivity variation is an important property in shallow subsurface investigation. Resistivity values of rock and soil are severely affected by pore connectivity and fluid type. Resistivity method is one of the geophysical surveys employed to map the subsurface structures. Resistivity data was collected using three different arrays (Wenner, Wenner-Schlumberger and Pole-dipole) on the homogenous ground with 5cm electrodes spacing. Subsequently, two identical square holes (20 cm x 7 cm x 30 cm) were made 10 cm below the ground surface and 20 cm apart. The resistivity data was collected again using the three different arrays across the two holes. The result for the homogenous ground shows a low resistivity value, while the homogenous ground with holes show high resistivity value around the holes. The results of the three arrays are then compared. The Pole-dipole array produced the best image of the two holes with a deeper depth of penetration.