On determination method of thermal conductivity of soil solid material

Abstract

Soil thermal conductivity always calculated by the thermal conductivity models and the thermal conductivity of each phase in soils, the thermal conductivity of water and gas can be obtained by physicochemical methods, while the test values of soil solid material always effected by the pore waters or pore gases. To determine the thermal conductivity of soil solid material, the calculation relationship between the thermal conductivity of soil solid material and thermal conductivity of soil is deduced based on the geometric average method and the Maxwell-Eucken method, respectively. Meanwhile, a theoretical model for calculating the two-phase medium (i.e., the soil solid material and water) is established by combining the software APDL, FORTRAN, ABAQUS, and the relationship between the thermal conductivity of the two-phase medium and the thermal conductivity of soil solid material is obtained. The thermal conductivity of saturated silty clay, saturated silty soil and saturated sand with different dry densities were tested by the probe method, and the thermal conductivity of soil solid materials are obtained according to the three calculation relationships between thermal conductivity of soil solid material and thermal conductivity of soil which established herein. Meanwhile, the thermal conductivity of model soils were tested to verify the absolute errors of the abovementioned calculation methods. The results show that, the nonlinear behavior induced by the soil-water interface will largely affect the test error of thermal conductivity of soil solid material, the theoretical model proposed herein can reduce the dispersion of the thermal conductivity of soil solid material, which can provide a reference for the prediction of soil temperature fields.