Exploring ice content on partially saturated frozen soils using dielectric permittivity and bulk electrical conductivity measurements

Yanxin Mao,Enrique Romero,Antonio Gens

doi:10.1051/e3sconf/20160907005

Yanxin Mao, Enrique Romero + Show 1 more

Open Access

https://doi.org/10.1051/e3sconf/20160907005

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Abstract

The present paper explores the use of the measurement of bulk electric conductivity and relative dielectric permittivity during freezing and thawing to estimate the ice content of two different partially saturated soils. The soils (Castelldefels fine sand and Barcelona clayey silt) were prepared at different degrees of saturation and dry densities at room temperature. Different target temperatures were used, which were reached at varying freezing rates and controlled with a thermal bath. Models were used to fit electrical conductivity and relative dielectric permittivity results under full unfrozen liquid and maximum ice conditions. The extension of these models allows estimating ice content on partially saturated soils at different porosities.

Highlights

IntroductionWhen dealing with the modelling of thermo-hydromechanical coupled processes induced by freezing of saturated and unsaturated soils, an important issue is the definition of the freezing retention model, which links the saturation degree of the liquid phase (unfrozen water) to the temperature of the soil
When dealing with the modelling of thermo-hydromechanical coupled processes induced by freezing of saturated and unsaturated soils, an important issue is the definition of the freezing retention model, which links the saturation degree of the liquid phase to the temperature of the soil
It can be observed that the values of bulk electrical conductivity (EC) and dielectric permittivity reduce with decreasing temperature until they reach a minimum, which indicates that the maximum ice condition had been achieved

Summary

Introduction

When dealing with the modelling of thermo-hydromechanical coupled processes induced by freezing of saturated and unsaturated soils, an important issue is the definition of the freezing retention model, which links the saturation degree of the liquid phase (unfrozen water) to the temperature of the soil. Determining experimentally the amount of ice content or unfrozen water in the frozen soils is necessary and helpful for verifying the correctness of the retention model and for defining the model parameters. For the direct measurement of ice content in frozen soil, several methods have been used, including gas dilatometry, dielectric spectroscopy and the heat pulse probe method (see for instance, [1]). Instead of measuring ice content directly, some authors combined two methods together to infer ice content and unfrozen water content in frozen soil [1, 2]. It is still difficult to measure the accurate ice content of frozen soil both in direct and indirect way

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