A generalized model for effective thermal conductivity of soils considering porosity and mineral composition

Soils have a variety of mineral compositions. Although a number of thermal conductivity models have been developed for soils, few quantitatively investigated the effect of mineral composition. In this study, the finite element method was employed to estimate the thermal conductivity of dry porous soils (kdry) considering the impact of mineral composition and porosity. A generalized model is proposed to predict kdry. The proposed model involves two steps. First, a modified form of Johansen’s model to evaluate the thermal conductivity of soil solid (ks) was established. The modified form considers a large number of soil samples where the soil composition varies and an empirical formula is obtained. Second, kdry is observed parabolically decreasing with porosity. Based on the relationship between kdry and porosity, a generalized model to predict the thermal conductivity of dry soil is proposed, and the empirical parameters for various types of soils are also determined for the sake of engineering applications. The performance of the proposed model is validated by comparing the predicted results with experimental data. A working illustration is exemplified for application of the generalized model.