Anisotropic thermal conductivity of unsaturated compacted GMZ bentonite-sand mixture

摘要

GMZ bentonite has been considered as a possible material for construction of engineered barrier in the Chinese program for disposal of high-level nuclear waste at great depth. In the present work, the anisotropic thermal conductivities of statically compacted GMZ bentonite and bentonite-sand mixture specimens were measured by the needle probe method. Quasi-cubic specimens with different dry densities, water contents and sand contents were prepared by statically compaction and the thermal conductivity were measured in directions both parallel and perpendicular to the bedding plane. Results show that the thermal conductivity measured at both directions increases with increasing dry density, water content and sand content. The thermal conductivity measured along the parallel direction is higher than that measured along the perpendicular direction; while the anisotropy coefficient (ratio of the parallel thermal conductivity to the perpendicular one) of the thermal conductivity increases with increasing dry density, and decreases with increasing water content and sand content.