Study on the instability characteristics and influencing mechanism of coal-rock parting-coal structure under triaxial loading

Rockburst accidents are highly likely to take place during the mining of coal seams in bifurcated area. A conventional triaxial testing machine and an acoustic emission (AE) monitoring system are employed to investigate the failure and instability characteristics of coal-rock parting-coal structure (CRCS) and its influencing mechanism. The results show that: (1) The instability process of the composite structure under the conventional triaxial path represents a coupled instability process of contact surface slipping and coal/rock fracture. The penetration of tensile fractures into shear fractures serves as the primary cause of the overall instability of the composite structure. (2) Alterations in the main frequency and maximum amplitude, a sharp decrease in the radiant energy index, and a significant increase in the cumulative apparent volume can be utilized as precursor identification information of the slipping and overall instability of the composite structure. (3) The inclination angle of the contact surface, confining pressure, and loading speed have an impact on the instability of the composite structure. Effectively controlling these factors during production can contribute to reducing the risk of impact disasters. The research results can provide theoretical support for the early warning and prevention of rockburst accidents in the bifurcated area.