Geophysical investigation to delineate hazardous cavities in al-hassa karstic region, kingdom of saudi arabia

Abstract

Near-surface cavities in karstic carbonate regions are of a particular engineering concern due to their propensity to cause ground subsidence and hazardous effects on the constructions. In a case study at Al-Hassa area, Kingdom of Saudi Arabia (KSA), traditional application of probing techniques has not thoroughly covered the study area due to economic, technical and time limitations. Therefore, buried near-surface cavities became a threat to the proposed constructions in the vicinity of the study area. In this paper, the application of an integrated geophysical survey to delineate the concealed cavities using ground penetrating radar (GPR) and 2D electrical resistivity tomography (ERT) will be presented. Cavities located down to 4 m below natural ground level were well detected by GPR, while those situated deeper than 4 m were well detected by 2D ERT. Correlation between geophysical and engineering geological data has shown a good agreement, indicating the great benefit of geophysical investigation in identifying the ground conditions for major engineering projects in karstic regions like Al-Hassa area. Around thirty two detected cavernous zones were confirmed by borings, and were subjected to suitable ground remediation.