Effect of mesoscale internal structure on effective thermal conductivity of anisotropic geomaterials

Geomaterials tend to be stratified due to the geological process, and their properties are often anisotropic. In this study, the quartet structure generation set (QSGS) method is adopted to reconstruct the mesoscale internal structure of anisotropic geomaterials. In addition, the fractal theory and several morphological parameters are employed to describe the structural features of anisotropic geomaterials. The effective thermal properties parallel and perpendicular to the layered structure are evaluated via the finite element method coupled with Monte Carlo simulations. A representative volume element of anisotropic geomaterials is determined by the homogenization method. The importance of morphological parameters is ranked by Pearson correlation coefficient. Results indicate that the porosity and arrangements of solid fabric have significant influences on thermal conductivity and its anisotropy. Prediction models for assessing the orthogonal thermal conductivities and anisotropic ratio are established, and their performances are benchmarked against the finite element analysis results. The results obtained from this work can provide a reference for the investigation of anisotropy of geomaterials properties and a link between effective thermal properties and features of the internal structure.