Abstract: We focus on the weak intercalation of Permian carbonaceous shale and analyze mineral composition, microstructure, and shear creep characteristics of Permian carbonaceous shale under different levels of normal stress during three evolutionary stages: original soft rock, interlayer shear zone, and sliding zone. The analysis results indicate that during the evolutionary process of the weak intercalation stage, the mineral compositions and content of the shale changed, and the clay mineral content gradually increased from less than 5% in the original soft rock stage to 5%-10% in the interlayer shear zone stage, and finally to greater than 10% in the sliding zone stage. The microstructure changed from compact to loose, and the bonding force between the particles was weakened. The creep displacement and the rate increases non-linearly with increasing shear stress. Under identical shear stress, the relationship of the creep displacement and the rate was that the sliding zone was greater than the interlayer shear zone, and the interlayer shear zone was greater than the original soft rock. The long-term shear strength gradually decreased, the drop in cohesion was greater than the angle of internal friction, and the cohesion was more sensitive to time than the angle of internal friction. The conclusions of this paper provided an important reference for the study of the development and mechanism of layered rock landslides controlled by weak intercalations.

Key words: carbonaceous shale, weak intercalation, shear creep, long-term strength, nonlinear damage creep model, evolutionary process