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Induced polarization and complex resistivity effects in soils : laboratory and in-situ measurements

University of British Columbia

Detection of subsurface contaminants is often carried out by different electrical measurement techniques and using an empirical relationship between electrical conductivity and Total Dissolved Solids. However, these methods provide no information about the ion types present in the subsurface. In this research, it was investigated if the polarization response of soil was effected by the ion types present in the groundwater. Two different methods were used to measure the polarization response of soil: The Induced Polarization (IP) method was used in-situ and in' the laboratory, whereas the Complex Resistivity (CR) method was used only in the laboratory. In-situ IP tests were carried out with a RCPTU piezocone at mine tailings impoundments and in natural soils. Repeatable IP tests in natural soils showed an increase in polarization response with a decrease in soil particle size. The polarization response of the mine tailings was very similar to that of the clay soil, but by normalizing with the resistivity, it was possible to distinguish the two materials. Laboratory tests indicated that no relationship exists between sulphate concentration and the polarization response. The in-situ tests indicated that relationships could exist between other ion type concentration and the polarization response, but insufficient data were collected to make any conclusions. The CR test was carried out in the frequency range 10 Hz - 13 MHz and was implemented on samples of silica flour with different ions in the fluid. Repeatable results showed that the polarization response using this technique was dependent on the ion concentration in the fluid. However, there were no differences in the polarization response between sulphate ions and an equivalent amount of other ions.

Thesis/Dissertation

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2009-03-25

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http://hdl.handle.net/2429/6532

Civil Engineering

University of British Columbia

UBCV

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