Optimization of Electrode Layouts for 3D-resistivity Imaging: Application to Water Infiltrations in an Experimental Dike

Embankment dikes can be subject to several phenomena such as internal erosion, which may lead to mechanical weakness and even a breach. Research needs include developing early detection methods to improve mitigation of hazard associated to these pathologies. Several international research projects aim at developing geophysical (non-intrusive or weakly-intrusive) methods as part of a toolbox for assessing changes occurring inside embankment dikes. More precisely, DC-Electrical Resistivity Imaging techniques (ERI) are known to permit monitoring of water content, clay content, and temperature changes within a porous medium. Until recently, there has been a research effort on the optimization of ERI data sets to increase the amount and reliability of information. In this paper, we try to take such approaches further as we apply and adapt them to 1) the fully 3D case (topography and physical properties) of an experimental dike and 2) the design of the electrodes positioning for increasing resolution and robustness ERI. This paper extends how to optimize electrode layouts to enhance the resolution capacity compared to a conventional layout. Results exhibit a significant improvement of the model resolution matrix, thus an expected enhancement of the robustness of future ERI images of the experimental dike.