On the thermal conductivity anisotropy of thinly interbedded rock

This study presents the results of investigation on thermal conductivity anisotropy of a typical kind of thinly interbedded rock, i.e., banded magnetite quartzite. Influence mechanism of main factors on the thermal conductivity anisotropy were studied through experimental and numerical approaches. Using optical scanning technique, distributed thermal conductivity on the sample surface was obtained through a series of parallel scanning lines. Based on the measured distributed thermal conductivity graphs, effects of the spatial location and geometric size of the analysis subdomain on the thermal conductivity anisotropy were investigated. The results indicated that local anisotropy factors calculated based on subdomains with different spatial locations show significant heterogeneous characteristics. The spatial inhomogeneity of anisotropy is mainly influenced by local variations of mineral bands thickness, visible fissure development and its orientation relation with bedding planes. With the increase of geometric size of analysis subdomain, the dispersion degree of the local anisotropy factors gradually reduced. Based on thermal contact theory, a finite element model was established to simulate the thermal conduction processes of thinly interbedded rocks and its anisotropic characteristics. The numerical model was calibrated based on the experimental results. Sensitivity analysis was performed to investigate the effects of main model parameters on the thermal conductivity anisotropy. The results of this study can provide better knowledge to the anisotropic thermal properties of interbedded rock masses.