Assessment of Frequency-Dependent Parameters of Stratified Soils for Lightning Response of Earth Electrodes

Typically, the frequency dependence of soil parameters is predicted by models or formulas that assume a uniform soil, although it usually presents a stratified structure. This work develops analytical expressions that allow to evaluating of the errors associated with the uniform soil hypothesis, in comparison with the hypothesis of a two-layered soil, taking as reference a field methodology for measuring the variation of soil parameters with frequency. The results suggest that in the case of a stratified soil, the frequency dependence of its parameters can be considered individually for each layer.