Soil Resistivity Measurements to Predict Moisture Content and Density in Loose and Dense Soil

Abstract

In the past, most of the soil electrical resistivity charts were developed based on stand-alone geomaterial classification with minimal contribution to its relationship to some of geotechnical parameters. Furthermore, the values cited a very wide range of resistivity with sometimes overlapping values and having little significance to specific soil condition. As a result, it created some ambiguities during the interpretation of observations which were traditionally based on qualitative anomaly judgments of experts and experienced people. Hence, this study presents soil resistivity values based on laboratory experiment with a view to predict the soil moisture content and density in loose and dense soils. This study used a soil box and a resistivity meter to test a clayey silt soil, increasing its water usage from 1-3% based on 1500 gram of dry soil. All the moisture contents and density data were observed concurrently with 25 electrical soil resistance observations being made on the soil. All testing and formula used were in accordance with that specified in BS1377 (1990). It was apparent that the soil resistivity value was different under loose (L) and compact (C) condition with moisture content (w) and density (ρbulk) correlations being established as follows; ρbulk(C) = 2.5991ρ-0.037, ρbulk (L) = -0.111 ln (ρ) + 1.7605, w(L) = 109.98ρ-0.268, and w(C) = 121.88ρ-0.363 with determination coefficients, R2 that ranged between 0.69 0.89. This research therefore contributes a means of predicting these geotechnical parameters by related persons such as geophysicist, engineers and geologist who use these resistivity techniques in ground exploration.