Numerical Study on Stress Relief and Fracture Distribution Law of Floor in Short-Distance Coal Seams Mining: A Case Stud
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ORIGINAL PAPER
Numerical Study on Stress Relief and Fracture Distribution Law of Floor in Short-Distance Coal Seams Mining: A Case Study Chunlei Zhang
. Ruimin Feng . Xibin Zhang . Wei Shen
Received: 12 May 2020 / Accepted: 3 August 2020 Ó Springer Nature Switzerland AG 2020
Abstract During the mining process of short distance coal seams group with high gas content, excavation of the protective coal seam will result in stress relief and fracture development which provides pathways for gas migration. Gas stored in the lower coal seam moves along the mining-induced fracture to the floor of the upper working face, which may cause the gas over-limit at the upper coal seam. This paper takes the short distance coal seams group in Xinghua coal mine as an example, theoretical analysis, numerical simulation and field monitoring are
C. Zhang (&) W. Shen Faculty of Architecture and Civil Engineering, Huaiyin Institute of Technology, Huai’an 223001, Jiangsu, China e-mail: [email protected] C. Zhang Department of Mining and Mineral Resources Engineering, Southern Illinois University, Carbondale, IL 62901, USA C. Zhang School of Mechanics and Civil Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China R. Feng Department of Chemical and Petroleum Engineering, University of Calgary, Calgary T2N 1N4, Canada
comprehensively applied to study the floor failure mechanism, pressure relief law and dynamic evolution of cracks induced by the mining of the second-right working face. The results showed that as the upper coal seam gradually advances, the pressure relief angle of roof and floor gradually decreases, and the pressure relief range and floor failure depth gradually increase. After the working face of the upper coal seam is advanced 100 m, the range of the pressure relief in the surrounding coal and rock masses approaches stable; the cracks in the shallow depth are mainly with small angles or type II shear cracks, and the cracks in the large depth are mainly shear-expansion with lager angles, and the amount of fractures in the floor reduces with the increase of the depth of the floor. It was found that the mining-induced fractures in the floor is distributed in the shape of an ‘‘O’’ ring, and as the working face advances, the range of this ‘‘O’’-shaped crack circle keeps moving forward but the width of the crack circle is basically unchanged. Finally, the lowlevel drilling field was used to control the gas from lower coal seams according to the stress relief and fracture distribution law, which achieved satisfied application effect and provided guidance for mine gas extraction in similar mining conditions. Keywords Stress relief Fracture distribution Short-distance coal seams Numerical simulation
X. Zhang Huaneng Coal Industry Co., Ltd., Beijing 100070, China
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Geotech Geol Eng
1 Introduction Approximately 92% of coal production in China is from underground mining, with an average mining depth of more than 600 m, and the minin
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