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.

Automated summary

This study investigates the thermal conductivity anisotropy of thinly interbedded rock through experimental and numerical approaches. Optical scanning technique is used to obtain the distributed thermal conductivity on the sample surface, and the effects of spatial location and geometric size on the thermal conductivity anisotropy are studied. The results show significant heterogeneous characteristics in the local anisotropy factors, which are influenced by variations in mineral bands thickness, visible fissures, and their orientation relation with bedding planes. A finite element model is established to simulate the thermal conduction process and anisotropic characteristics of the rock, and sensitivity analysis is performed on the model parameters. The findings contribute to a better understanding of the anisotropic thermal properties of interbedded rock masses.