Quantitative calibration method for the evolution of mechanical properties of gas-containing coal under mining-induced stress and microscopic failure evaluation

Abstract

Current quantitative characterization methods for the mechanical response and damage evolution of coal seams at different burial depths under mining-induced stress remains insufficient. To address this, this study establishes a quantitative characterization model for the evolution of mechanical properties in gas-bearing coal masses at varying burial depths. It innovatively introduces a dual damage quantification technique and develops a coupled damage evolution model that comprehensively considers energy evolution, effective mining-induced stress, permeability, and a damage sensitivity coefficient, followed by extensive analysis. Key findings include: coal damage exhibits heterogeneous evolutionary characteristics under mining-induced stress; based on the theory of irreversible deformation, the proposed damage characterization equation can effectively determine the critical damage threshold of coal; the three-parameter EXP function model is more suitable for characterizing the time-dependent damage process of coal under mining-induced stress; a new characterization method for the coal brittleness evaluation index is proposed, revealing an 800 m burial depth boundary for the coal brittleness index; at the microscopic level, achieving quantitative characterization of the correlation between peak stress and the average reduction in functional groups during mining-induced failure of coal at different burial depths. Finally, the mapping relationship between laboratory experimental parameters and field monitoring indicators for early warning of coal mine dynamic disasters is established.

Keywords

Mining-induced stress / Coupled damage / Quantitative characterization / Energy evolution

CRediT authorship contribution statement

Zeqi Wang: Writing – review & editing, Writing – original draft, Software, Project administration, Formal analysis. Liang Yuan: Resources, Funding acquisition. Bin Hu: Validation, Software. Bo Li: Visualization, Conceptualization. Laisheng Huang: Project administration, Data curation.

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

The authors gratefully acknowledge the National Key Laboratory of Deep Coal Safe Mining and Environmental Protection for providing the test site and test materials.

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