A generalized thermal conductivity model for soils and construction materials

TLDR

The study develops a generalized thermal conductivity model for moist soils based on normalized conductivity relative to dry and saturated states. The model incorporates porosity, saturation, mineral composition, grain size, and particle shape, uses a geometric model for saturated soils, and is calibrated against 220 literature data for dry soils and more than 650 tests for moist soils to produce a unified empirical relationship. The model correlates normalized thermal conductivity with saturation for over 650 tests across gravels, sands, silts, clays, peat, and crushed rocks.

Abstract

This paper intends to develop a generalized thermal conductivity model for moist soils that is based on the concept of normalized thermal conductivity with respect to dry and saturated states. This model integrates well the effects of porosity, degree of saturation, mineral content, grain-size distribution, and particle shape on the thermal conductivity of unfrozen and frozen soils. The thermal conductivity for saturated soils is computed with the use of a well-known geometric model that includes the unfrozen water content in frozen fine-grained soils. Nearly 220 experimental results available from the literature were analysed to develop a generalized empirical relationship to assess the thermal conductivity of dry soils. A general relationship between the normalized thermal conductivity of soils and the degree of saturation using a soil-type dependent factor was used to correlate the normalized thermal conductivity for more than 650 test results for unfrozen and frozen moist soils, such as gravels, sands, silts, clays, peat, and crushed rocks.Key words: heat transfer, soils, degree of saturation, mineral content, unfrozen–frozen, thermal conductivity.