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Geoelectrical methods which use using continuous current (DC) are widely applied for geological, hydrogeological and geotechnical studies. These are applied for the identification of aquifer layers, minimum resistance zones, landfills and landslide failure surfaces.
This study applies geophysical methods for the identification and contouring of rich fluid strata, landslide failure surfaces of old dumps from the mining industry, as well as in other geohazard areas. The selected examples are from the central part of Romania. Resistivity anomalies obtained from geoelectrical field measurements are given by specific geological mechanisms and reflect the deep geological structure.
Geoelectrical studies were involved because the conventional geological methods could not clearly give an accurate geological picture of the studied areas. This is why geoelectrical measurement profiles were made together with other investigation techniques, such as drilling and coring. Because the areas of interest are 1-2 m thick and could be found up to 20 m depth, Vertical Electrical Sounding (VES) methodology was applied, using a Schlumberger array, with constant distance between current line (AB/2) and measurement line MN of 1 m. The selection of the VES methodology was based on the fact that its lateral effects are minimal and investigations can be done on higher depths compared to other arrays.
Data modeling was made by involving a new numerical model, which had been tested in several areas with known geological structures (outcrops). The models of the VES curves measured of studied outcrop top helped us to obtain a very clear identification of the geological layers which occur in outcrops. This means that the tests of the numerical model output data were successful, confirming data obtained from direct observations.
Geoelectrical measurements are presented as geoelectrical sections, on which it is very easy to identify areas with humidity variations and/or minimum resistance, landfills or landslide failure surfaces. These zones can be differentiated on the basis of resistivity variations, which, at their turn, are influenced by the fluid contents.
We therefore state that the application of the geoelectrical method in the previously mentioned situations is very useful, as it offers supplementary geotechnical information, as well as a general view of the horizontal and vertical distribution of low resistance and landslide failure surfaces.
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