Shear creep characteristics of weak carbonaceous shale in thick layered Permian limestone, southwestern China

Journal of earth system science

Wei Yingjuan^4¹  Zhu Sainan^1,2²  Li Bin^3³  Yin Yueping^1⁴ 

[1] China Aero Geophysical Survey and Remote Sensing Center for Land and Resources, Beijing 100083, People’s Republic of China.^4;China Institute of Geo-Environment Monitoring, Beijing 100081, People’s Republic of China.^1;Institute of Geo-Mechanics, Beijing 100081, People’s Republic of China.^3;School of Engineering and Technology, China University of Geosciences, Beijing 100083, People’s Republic of China.^2

关键词: Carbonaceous shale;    weak intercalation;    shear creep;    long-term strength;    nonlinear damage creep model;    evolutionary process;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Several weak intercalations of carbonaceous shale, which are commonly developed in the Permian thick limestone strata in Wulong County, Chongqing, southwestern China, form a structure of alternating layers of soft and hard rocks, which control the stability of massive layered rockslides. We focus on the Permian carbonaceous shale and analyse its mineral composition, microstructure and shear creep characteristics during the three evolutionary stages. The analysis results indicate the following: (i) During the evolutionary process of the carbonaceous shale, the microstructure changed from compact to loose, and the clay mineral content gradually increased from less than 5% in the original soft rock to 5–10% in the interlayer shear zone, and finally to greater than 10% in the sliding zone. (ii) Under the identical shear stress, the creep displacement and rate gradually increase nonlinearly. Under the identical normal stress, the long-term shear strength gradually decreases, and the drop in cohesion is greater than the internal friction angle. (iii) We established an improved Burgersnonlinear damage creep model, which fully reflected the creep deformation process of the carbonaceous shale. The fitting curve of the model matched the experimental results well.

【 授权许可】

CC BY