Predicting the engineering and transport properties of soils using fractal equivalent circuit model: Laboratory experiments

Frequency-dependent electrical measurements of soils contain useful information about their texture and structure that can be linked to their engineering and transport properties. We performed frequency-dependent electrical measurements on 29 natural soils with wide variability in physical and textural properties in a laboratory environment at a constant stress level and in the frequency range of 0.01 Hz-10 kHz. The engineering and hydraulic properties of these soils, that is, the hydraulic conductivity K, void ratio e, fines content fc, intergranular void ratio eg and the dry density γd are concurrently measured. The electrical behaviors of the soils are modeled with an equivalent circuit model, which are described by six circuit parameters. Relationships between the circuit parameters and the soil properties (geotechnical engineering and hydraulic) are investigated. Crossplots of frequency exponent η and resistivity ρ0 and that of η and grain percent resistivity δr clusters soils with high and low values of hydraulic conductivity, whereas crossplots of relaxation time τ and ρ0 clusters soils with high and low intergranular void ratio. Regression models are developed using the parameters η and δr to predict the hydraulic conductivity with R2=0.85; ρ0 and τ to predict the intergranular void ratio with R2=0.74 and ρ0 and η to predict the dry density with R2=0.67. © 2011 Society of Exploration Geophysicists.

Duke Scholars

Author Fred K. Boadu Civil and Environmental Engineering