Directivity effect of unloading bedding coal induced fracture evolution and its application

• Published in: International journal of mining science and technology Vol. 27; no. 5; pp. 825 - 829
• Main Authors: Rongkun, Pan, Dong, Fu, Minggao, Yu, Lei, Chen
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2017; Department of Safety&Science Engineering, Henan Polytechnic University, Jiaozuo 454003, China; The Col aborative Innovation Center of Coal Safety Production of Henan Province, Henan Polytechnic University, Jiaozuo 454003, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China; Henan Key Laboratory of Prevention and Cure of Mine Methane&Fires, Jiaozuo 45403, China%Department of Safety&Science Engineering, Henan Polytechnic University, Jiaozuo 454003, China%Department of Safety&Science Engineering, Henan Polytechnic University, Jiaozuo 454003, China; Elsevier
• Subjects: Bedding structure; direction;Bedding; evolution; Fracture evolution; Gas permeability; permeability;Fracture; structure;Gas; Unloading; Unloading direction; Gas permeability; Bedding structure; Fracture evolution; Unloading direction
• ISSN: 2095-2686
• DOI: 10.1016/j.ijmst.2017.07.022

In the coal mining process, the gas contained in the coalbed is one source of the most serious accident hazards. Stress releasing from the coal deposit is the main controlling factor that leads to such accidents. Based on the bedding of coal samples, the gas permeability well describes the evolution of fracture, so the paper carries out research on the permeability properties of coal under different unloading directions. The research obtains that when the stress unloading direction is perpendicular to bedding, more penetrating fractures and bedding fractures occur, and the permeability significantly increases. Although the axial stress reduced, the confining pressure makes the permeability of the bedding plane fracture exist under constant. The permeability obtained when the unloading direction was perpendicular to the bedding is 52 times larger than that when it is parallel to the bedding. The results show that the efficiency of gas drainage is impacted by the relative direction of gas drainage drilling in relation to the bedding orientations. The maximum amount of gas extraction when drilling is perpendicular to the bedding is 1.3 times than that when drilling is oblique to the bedding, and 1.75 times than that when drilling is parallel to the bedding.