Studies On Electrical Resistivity Of Perth Sand
J Ross Publishing Inc.
Faculty of Health, Engineering and Science
School of Engineering / Centre for Communications and Electronics Research
This paper presents experimental and numerical studies on electrical resistivity of Perth sand in its very loose state to very dense state. A simple laboratory experimental setup was developed to measure the electrical resistivity in terms of its apparent value, using the Wenner array of electrodes. The electrode spacing and depth were varied to investigate their influence on the resistivity values. The results indicate that an increase in electrode depth causes a decrease in resistivity, whereas an increase in electrode spacing results in an increase in resistivity for all the relative densities of sand. In view of limitations with respect to the geometry and electrode configuration of the laboratory setup, the values determined using the classical Wenner array expression ρ = 2πa(ΔV/I) (I = current, ΔV = potential difference, a = equal electrode spacing, and ρ = electrical resistivity) required corrections by a suitable factor. To determine this correction factor for a specific electrode arrangement, say electrode depth = 150 mm, electrode spacing = 180 mm, as an example, in our resistivity box, finite element (FE) simulation was carried out using the commercial software COMSOL. The simulation results indicate that a correction factor of about 0⋅46 should be applied to the value calculated using the expression in order to obtain more realistic values. By employing this methodology, it was found that the electrical resistivity of dry Perth sand ranged from 60 606 Ω m for the very dense state to 142 857 Ω m for the very loose state.