Combined geophysical methods to the detection and filling certification of cavities

Summary In this paper, we present the results from the implementation and interpretation of a geophysical survey, realized in the extension area of an industrial building. During the excavation of the limestone formation in the area, a void appeared having a horizontal and a vertical extend up to several meters. The objective of the geophysical investigation was the detection of possible additional voids in the remaining area. Based on previous experience in similar geological environment, initially, we used geophysics to detect voids and then, secondly, to verify the completion of the consolidation of the ground after filling the discovered voids. The geophysical data results were very clear since all the methods employed indicated the initial existence of the voids which were then vanished, a fact that verified the success of the consolidation process. However, there were cases where voids were drilled in greater depths than the indicative depth by the resistive body. A possible reason to explain these cases is that resistive body is that apparent resistivity values are affected by deeper voids leading to false resistive targets. The effectiveness of the filling of the cavities has been checked by the repeated geophysical measurements after the end of the filling procedure.