Case study regarding the stress distribution and microseismic laws of coal and rock underlying the residual coal pillar

• Published in: Lithosphere Vol. 2022; no. Special 11
• Main Authors: Liu Yang, Liu Yang, Lu Caiping, Lu Caiping, Zhang Xiufeng, Zhang Xiufeng, Guo Ying, Guo Ying, Song Jiefang, Song Jiefang, Song Chunhui, Song Chunhui
• Format: Journal Article
• Language: English
• Published: GeoScienceWorld 2022
• Subjects: Asia; Baodian Mine; body waves; case studies; China; coal mines; coal seams; elastic waves; Engineering geology; Far East; geologic hazards; geophysical methods; microseisms; mines; mining; natural hazards; P-waves; pillars; rock bursts; rock mechanics; room-and-pillar mining; seismic methods; seismic waves; Shandong China; stress; underground mining
• ISSN: 1941-8264; 1947-4253
• DOI: 10.2113/2022/4370718

The stress distribution characteristics, stress gradient evolution, and focal mechanism of microseism (MS) events during mining of working face 103_ (lower) 07 under an overlying residual coal pillar were investigated. Numerical simulations and MS observations were utilized. The coupling relationship between the stress gradient and MS activity was also analysed, which indicated the correlation between the fracture of coal/rock and stress gradient. In addition, the secondary disturbance of the coal mining underlying a fractured hard-thick roof is discussed. The following four points were addressed: (1) the high stress initially concentrated under the edge of the overlying residual coal pillar, and its contribution to both the local coal and rock fracture and the significant change in the stress gradient; (2) the deformation and fracture first occurred in coal and rock underlying the edge of the residual pillar. The stress concentration gradually transferred to the interior of the pillars and was accompanied by the failure of coal and rock; (3) a high correlation between the deformation and fracture of coal/rock and the stress gradient was observed. The fractures under the pillars principally appeared in the high-stress gradient area; (4) the disturbance caused by mining of the underlying working face may cause instability of the high-level fractured roof, accompanied by high-energy MS.