Energy characteristics during the progressive shear failure of rock joints and brittleness evaluation

Abstract

The energy-driven progressive brittle shear failure of rock joints is a key mechanism behind deep engineering disasters such as joint-induced rockbursts and engineering earthquakes. To investigate the energy evolution mechanisms and disaster proneness, monotonic and stepwise loading-unloading tests were performed on regular dentate joints under constant normal stiffness boundary conditions. Results indicate a transition in damage mechanism from climbing wear of low-inclination asperities to brittle rupture of high-inclination ones, accompanied by a marked decrease in irreversible displacement. Energy analysis reveals a strong linear relationship between pre-peak elastic energy density and both input energy density and shear stress squared. The post-peak elastic energy release rate (g), and the self-sustaining instability coefficient (l) increase with joint undulation. A dimensionless brittleness index (BI) integrating the complete energy conversion and release process was proposed to quantify the energy balanced budget. The highly undulated joint R₄ showed the most pronounced brittleness and instability intensity with the high BI value of 0.697, along with g 0.774 and l 0.611. This study provides deeper insight into the understanding of the disaster-inducing proneness and stability assessment in jointed rock mass.

Keywords

Rock joints / Loading-unloading / Progressive shear failure / Energy evolution / Shear brittleness

CRediT authorship contribution statement

Jianan Yang: Writing – original draft, Methodology, Investigation. Pengxian Fan: Methodology, Funding acquisition, Formal analysis. Junhui Wang: Writing – review & editing, Investigation. Haozhe Xing: Writing – review & editing. Mingyang Wang: Writing – review & editing, Methodology. Qihu Qian: Writing – review & editing, Methodology.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

Partial financial support was received from the National Key Research and Development Program of China (No. 2024YFF0508204), and the National Natural Science Foundation of China (Nos. 52438007 and 12372378).

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