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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:36 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Atmosphere and Earth Science; Environment Protection
Title:
Indirect determination of soil electrical resistivity
Authors:
Serban Adrian
Affiliation:
University of Bucharest, Faculty of Physics, P.O.BOX MG-11, Magurele, Bucharest, Romania
E-mail
serbanaddy@yahoo.com
Keywords:
VES =Vertical Electrical Sounding
Abstract:
Soil and rocks can be characterized and differentiated by using their capacity of electrical current conduction or opposition to electrical current flow.Among the electrical properties (spontaneous or natural electric potentials, electrical conductivity or its inverse, dielectric permittivity) the apparent electrical resistivity is one of the most used parameter in soil – affected environmental problems.Electrical resistivity of rocks and soil can be measured directly if the probes have regular geometrical shapes or cross sections. When this requests cannot be fulfilled or direct probes are not available one can determinate the electrical properties of soil by using the indirect methods. An indirect way to obtain information of electrical resistivity variation with depth is the application of the VES (Vertical Electrical Sounding) method. The method consists in injecting into the soil, a DC electrical current of a known intensity and to measure the resulted potential difference. The depicted parameter, named apparent electrical resistivity, is calculated considering the ratio of potential and induced current intensity but also the geometric factor of the used array.The injection and potential electrodes can be arranged in different relative positions, but for practical application in field and easily data interpretation are preferred the linear quadripolar arrays. In this paper, simulation of VES measurements over few different soil vertical profiles will be presented: continuous increasing resistivity for six layers and alternating resistivity. Using Schlumberger and Wenner arrays differences in soil apparent resistivity estimations are noticed. Such results are caused by the reached depth for a certain injection line extent, layer thickness and model resistivity variations, but also as a consequence of simplifying assumptions of current flow in half-spaced medium. Even these inherent existing inaccuracies in data determination, results showed that SEV measurements remains a valuable tool for non invasive investigation of underground soil and rocks properties.
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