Protection of electricity transmission infrastructure from sinkhole hazard based on electrical resistivity tomography

Sinkhole formation induced by limestone quarrying has the potential to cause severe environmental problems that impact agricultural activities and damage property. Moreover, sinkholes present a stability hazard to critical infrastructure such as power transmission towers. Field investigations in northeast Thailand found surface expressions of potentially dangerous sinkholes adjacent to a limestone quarry. 2D electrical resistivity tomography (ERT) profiles were deployed across previously mapped fractures that are located near power lines in order to detect the presence of subsurface structures and cavities in the carbonate bedrock. A 3D ERT survey was conducted near the base of power transmission tower T1 to precisely determine variations in subsurface material and structures. The ERT results were combined to delineate possibly hazardous cavities and continuous fractures. The surficial collapse features were generally observed to be in alignment with interpreted subsurface cavities and fractures. Water-table declines, quarry dewatering, and quarry blasting are possible triggers for the formation of the sinkholes. Additional sinkhole collapses could intensify along specific air-filled cavity zones in the near surface. Professional evaluations and regulatory action may be necessary to limit further quarry dewatering activities and prevent additional sinkhole collapses and further risk to the power infrastructure.