New technique of electrical soundings: theoretical modeling and experimental application in study of state of the soil dam

The results of mathematical modeling of electrical soundings with the AMNB (Schlumberger, Wenner) arrays and the proposed combined AMN + NMA array above horizontally layered medium and including a ball medium are presented. It is shown that the combined array has two main advantages: the current penetration depth is greater at the same position of outer electrodes of the considered arrays; edge effects are smaller due to bilateral measurements with respect to the central receiving electrode; a geoelectric inhomogeneity is delineated at the pseudosections of the apparent resistivity. The quantitative interpretation of the sounding curves obtained with the AMN + NMA array can be carried out by an existing software for inversing of data of the symmetric Wenner (AMNB) array with electrode spacing equal to 1/3 of supplying dipole. The results of application of the new technique of electrical soundings by the combined array in the study of state of the dam on sedimentation tank of liquid chemicals are presented. On the geoelectric sections and the pseudosections of the apparent resistivity, areas of increased electrical conductivity in body and base of the dam are detected. Filtration of water from the reservoir occurs through these areas. Soundings with the AMN + NMA array are expedient for studying of a geological medium at small depths where the medium is horizontally-heterogeneous, and also for solving of engineering-geological problems.