The Evolution of Induced Polarization Method in Engineering Investigations

Abstract

The Induced Polarisation (IP) method extends the resistivity method by making an additional measurement of the ability of the ground to store electrical charge. Originally developed for mineral exploration, it is now finding new applications in the fields of environmental and engineering geophysics. IP instruments measure both the conductive and capacitive properties of the subsurface using either time domain or frequency domain techniques. The low frequency capacitance of rocks and soils is primarily a function of the surface chemical properties of the sample. In non-metallic samples the IP response is an indicator of surface area and charge density of the material. IP measurements are therefore sensitive to clay content as well as mineralogy and pore fluid composition. IP methods have been used to estimate the hydraulic properties of rocks and soils as well as to map subsurface contamination. The method is also sensitive to subsurface metals. Recent advances from laboratory investigations, new instrumentation and software development have advance the study of the use of IP in Engineering Investigations. In this review, we summarize these recent advances and discuss how the IP method can be applied to engineering problems. Applied research in engineering applications of the IP method should prove lucrative and be encouraged.