Using Laboratory Electrical Resistivity Testing to Estimate Geotechnical Properties of Some Bhubaneswar Region Soils

Abstract

Electrical resistivity testing is a well-known geophysical method for the quick assessment of subsurface conditions. It can be performed at a reasonable cost and is known to correlate well with major geotechnical properties of soil. This study was performed to study the variations in electrical resistivity of some local soils and correlate them with some of their geotechnical properties. For this purpose, soil samples were collected from around the Mahura region of Bhubaneswar which included some red lateritic soil, greyish-brown clayey soil, and poorly graded sandy soil. An inexpensive four-electrode soil resistivity box was fabricated and was used for measuring the resistivity of these soils. The Wenner electrode configuration was used for the measurements. Electrical resistivity was measured by applying a 25 V DC through the outer electrodes of the soil box and measuring the ensuing potential difference the two inner electrodes. Variations in resistivity were studied with respect to changes in soil types, moisture content, dry density, and clay content. Resistivity showed a decreasing trend with increase in moisture, dry density, and clay content. Multivariable linear regression analysis was performed to model resistivity as a function of moisture, density, and clay content using the data analysis tool of MS Excel. The multivariable regression models displayed a fairly good correlation between resistivity and the soil variables with R-squared values in the range of 0.75–0.87. The results from this study could be used as a basis for estimating the basic soil properties from field testing methods.KeywordsElectrical resistivitySoil resistivity boxClay content