Electrical resistivity of sandy soil

Abstract

This paper presents the results of an investigation into the interaction between the various electrical factors pertaining to resistivity tests in Perth sandy soil (specifically AC input voltage and frequency) and those controlling the soil characteristics, specifically water content and relative density of the soil, and the type of water employed in the tests, whether distilled or tap water. The experimental apparatus was developed as per Australian standard AS 1289.4.4.1-1997 and was used for the electrical resistivity measurements. The test results indicate that the resistivity of the sandy soil is almost independent of both AC input voltage and frequency within the ranges used, while the choice of electrode material has an insignificant effect on the outcome of tests using this method. It was observed that the resistivity of sandy soil decreased rapidly with an increase in water content, but the rate of decrease reduced considerably for water contents over 12% in the case of distilled water and 10% for tap water, irrespective of the relative density. The resistivity was found to decrease almost linearly with an increase in relative density. However, the effect of relative density on the electrical resistivity of the soil was found to be negligible at higher water contents. Correlations between electrical resistivity, water content and relative density, which are applicable to the soil and water used in the study, are also presented.