Experimental research on the tensile properties of coal rocks in deep old goafs
Ning Jiang,Quanbao Su,Xia Jiang,Zhiyou Gao,Qingbiao Guo,Shijie Song,Tao Lyu,Ke Lyu
Abstract
The pressurized water conditions of goafs weaken the support of remaining coal and rocks, which causes instability, failure, and sudden ground collapse. The impact of pressure-bearing water and CO2 on the tensile properties of residual coal pillars was explored in old goafs. Coal was analyzed using a pressure-water soaking device, electronic scanning microscope, and 3D full-field strain measurement system. Besides, Brazilian splitting tests were performed. The failure characteristics and energy evolution law of the macro-microscopic structure of coal specimens were analyzed under different soaking conditions—desiccation (DC), CO2 soaking (CS), water-CO2 soaking (WCS), and water soaking (WS). The peak stress of coal specimens and time to reach the peak decreased with varying soaking environments. Stress concentration initially occurred at the water end under the WCS condition, indicating that coal specimens deteriorated more under the pressure-bearing WCS condition compared with the CS condition. Fractures of coal specimens exhibited the highest development under the WS condition. Besides, dissolution was observed at the fractures of coal specimens, with severe failure to their internal microstructures. In conclusion, the instability failure of residual coal pillars is significant in studying the old goafs.
Ning Jiang — College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China; State Key Laboratory of Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China
Quanbao Su — College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China
Zhiyou Gao and Tao Lyu — College of Energy and Mining Engineering, Shandong University of Science and Technology, Qingdao 266590, China; Shandong Geology and Mineral Resources Engineering Group Co., Ltd., Jinan 250013, China
Qingbiao Guo — School of Spatial Informatics and geomatics Engineering, Anhui University of Sciences and Technology, Huainan 232001, China
Shijie Song — College of Geology& Environment, Xi'an University of Science and Technology, Xi'an 710054, China
Ke Lyu — School of Mines, China University of Mining and Technology, Xuzhou, Jiangsu, 221116, China
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