Application of GPR to identify carbonate rock cavities related to ground subsidence in Matale, Sri Lanka

Abstract

Cavity formation within the rocks result in ground subsidence in the regions where carbonate rocks are predominantly present. Identification of ground subsidence potential areas and the probability of such incidents is a challenge without detailed information about the subsurface. Dorakumbura in Matale, Sri Lanka is one such area which faced multiple ground subsidence incidents that demands the investigation of subsurface profile. This study uses Ground Penetrating Radar (GPR) to locate the subsurface cavities in order to create a cavity profile for the Dorakumbura area using 1D and 2D trace analysis of the radargrams. Cavities were identified and analyzed and the results reveal the existence of cavities mostly below the depth of 15 m. Comparison of GPR survey results with the well log data in the region was equivalent. The same methodology is expected to be used in similar regions to identify the presence of cavities which can result in future ground subsidence. It can also assist in suitable site selection without ground subsidence hazards, for the construction and development activities in regions underlying carbonate rocks in Sri Lanka.