Caves and Fractured Zones Investigation Using 2D Electrical Resistivity Imaging in an Engineering Site, Haqlaniyah, Western Iraq

Abstract

Engineering risks in karstic areas are represented by cavities and voids near the surface, which are considered potential geotechnical hazards (land subsidence and building cracks). These hazards are caused by dissolution processes that occur when carbonate rocks interact with water, forming weak zones. This study used 2D electrical resistivity imaging with a dipole-dipole array. The spacing of 5 m and an n-factor of 6 were applied to investigate four parallel traverses covering an area of 95x45 m. Electrical resistivity imaging data was inverted using RES2DINV software by robust method inversion. The results show relatively high resistivity values interpreted as massive limestone with cavities and relatively low resistivity values interpreted as fractured limestone with clay or moisture content. Because of the consequence of these caves' haphazard existence in the area, the region was characterized by significant heterogeneity levels of resistivity rise until a depth of 15 m. At that point, they begin to decline.