TOWARDS A BETTER UNDERSTANDING OF THE ELECTRO-MAGNETIC PROPERTIES OF SOILS

摘要

Given the sensitivity of soils to disturbance, the use of low perturbation (i.e., non-destructive) electromagnetic waves provides a viable option for studying soil properties. The measured parameters during the excitation of a material by an electromagnetic wave are electrical conductivity, dielectric permittivity, and magnetic permeability. Electrical conductivity is a measure of charge mobility in response to an electrical field. Dielectric permittivity represents the polarizability of a material. Magnetic permeability indicates the degree of magnetic dipole alignment within a material under the excitation of the magnetic field. Factors that affect electromagnetic wave parameters include water content/degree of saturation, porosity, spatial distribution of the phases (e.g., an-isotropy), particle properties (e.g., specific surface), pore fluid characteristics, and temperature. This paper presents a review of electromagnetic parameters, provides experimental data showing the impact of the various factors on the electromagnetic response, and gives a physical explanation of why these factors affect electromagnetic properties. Finally, various applications of electromagnetic wave-based techniques are presented, including monitoring the diffusion of salt through a soft kaolinite sediment and the hydration process in cemented paste backfill.