A generalized thermal conductivity model of geomaterials based on micro-structures

Knowledge of particle shape and configuration-dependent thermal conductivity is necessary to investigate heat or water transfer in geomaterials, especially under freezing states. Thermal conductivity of a porous medium is affected by its matrix components and particle shapes. However, the particle shapes in geomaterials are various, and the effect of the ice phase on the thermal conductivity may increase substantially as ice content increases from unfrozen to freezing. In this study, a generalized thermal conductivity model for geomaterials is proposed based on phase transition theory and geometry approximation with respect to unfrozen and freezing states. Volumetric contents of each component and shape factors are required to predict thermal conductivities by the model. In order to evaluate the model, test results from both ours and previous literatures are employed to evaluate the calculated ones, and they match very well. In addition, compared with the other two models, i.e., a physical model and an empirical model, the proposed model is more reasonable and effective.