PHYSICAL MODELING OF ELECTRICAL RESISTIVITY TOMOGRAPHY ON GROUND SURFACE WITH A COMPLEX RELIEF

Abstract

Currently geophysicists actively use the method of ERT for a wide class of geotechnical problems. Often work is performed in rough terrain where there are areas with significant elevation changes of the earth's surface commensurate with the size of the electrical array, and which lead to the distortion of the electric field. The main types of distortion electrical fields on different forms of relief are known, and in all inverse programs provides for the consideration of the influence of topography. But issues remain with the accuracy of the calculation of the direct problem, which is embedded in the inverse problem, not the known values of the critical angles of the terrain that can cause the strong distortion of the field. Therefore, the question about the influence of the topography of the land results two-dimensional inversion of electrical tomography data is the actual geophysical problem. To solve this problem, the authors performed physical modeling on large homogeneous sand embankment with artificial complex surface topography. The mound was located on a laterally homogeneous loamy earth's surface. This experiment allowed us to identify false anomalies that were the result of a two-dimensional inversion for geoelectric sections. In addition, the simulation in the laboratory in a rectangular tank filled with cellulose-hydro gel mixture. The positive slope of the terrain relative to the background surface was 30 degrees. The result has distinguished four types of severe anomalies of the electric field. Geoelectric sections, obtained through inversion, were considered. It is shown that on steep bends of the relief, 2D-inverse program does not complete this task sufficiently. As a result of abnormalities of a different type from the adjacent landforms are summed with each other and complex patterns appear on the pseudo-sections of apparent resistivity. Therefore, the anomalous zones are formed on the geoelectric section which can explain how some objects, which actually does not exist.