Bode and nyquist plots: assistance in soil characterization

Abstract

Climate change is a phenomenon manifested for instance, among other things, by alternating dry and flood episodes with an impact on the environment. Therefore, one must deal with the issues such as: how to retain water in the landscape, protect the soil from erosion or oneself from the consequences of floods. There are used well-known and proven principles supplemented by modern techniques and technologies to understand individual processes and solve their impacts. Electrical impedance spectrometry (EIS), in which a sinusoidal test voltage or current is applied to the sample under test to measure its electrical impedance over a suitable frequency range, is a powerful technique to investigate the electrical properties of a large variety of materials. EIS is used in a broad range of applications as a quick and easily automated technique to characterize solid, liquid, semiliquid, organic as well as inorganic materials. The subject of interest of the paper is the monitoring of selected soil characteristics in the water-soil interaction. Measurement of electrical impedance of soils in the frequency spectrum and processing of results in the form of Bode and Nyquist plots provides information on the water content in the soil and the possibility of estimating its structure. This is very important for various purposes of engineering geological practice, and especially for constructions. Model or limit curves of grain size, table values or indicative standard characteristics are used for the approximate assessment of some soil characteristics. Often, selected soil characteristics are described by the size of their effective grain or this parameter is used in mathematical formulas. In practice, the measured impedance spectra, represent an electrical fingerprint of the sample providing an insight into its properties and behaviour. The selected measurement results are obtained by new apparatus with Z-meter device in field and[...]