Electrical Anisotropic Response of Water Conducted Fractured Zone in the Mining Goaf

Abstract

Based on the Maxwell equation, the occurrences of fractured zones are studied through the galvanic method. The electrical and magnetic fields are first derived in the spatial domain. To simplify the calculations, the computational formulas of the electrical fields in the spatial domain are transformed into the wavenumber domain by the Fourier transform. The basic solution of the electromagnetic field can thus be easily solved in the wavenumber domain. According to the boundary conditions, a recursive relationship between the different layers is established. The electromagnetic fields are obtained through the recursive relationships with the bottom-last layer. Finally, the apparent resistivity is calculated using the surface electric field. A typical goaf model is used for the numerical simulation. Based on the modeling results, the effectiveness of this method is determined. The modeling results indicate that the galvanic method is very effective for detecting the electrical anisotropic characters.