f EARTHEN EMBANKMENT DAM INSPECTION USING ELECTRICAL RESISTIVITY TOMOGRAPHY

Two quarter scaled experimental embankment dams were constructed at the USDA ARS Hydraulic Engineering Research Unit in Stillwater, Ok. These dams were constructed with two internal compromised zones that would be susceptible to seepage and piping. The zones consist of a sandy region and a region compacted at a lower moisture content. Preliminary measurements were performed on the dam during construction to gain initial resistivity of the zones and the dam body. These measurements showed that there was a good contrast between the zones and the dam body. This will make the anomalous zones easily visible in our initial tomograms. Electrical resistivity surveys have been performed on the embankments for over the course of a year to monitor changes in electrical signatures of the dam due to environmental changes and cyclic loading and unloading of the reservoir. Also forward modeling was performed using the EarthImager 2D imaging software. These models will help predict changes in the resistivity of these zones due to infiltration of water from the reservoir or from rainfall and also due to the removal of fines/clay content during piping. Field measurements are then going to be compared to the forward model predictions. [This research was funded by the Department of Homeland Security-sponsored Southeast Region Research Initiative (SERRI) at the Department of Energy’s Oak Ridge National Laboratory.]