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Hancheng, China

Yang W.,The State Key Laboratory of Coal Resources and Mine Safety | Yang W.,China University of Mining and Technology | Lin B.-Q.,The State Key Laboratory of Coal Resources and Mine Safety | Lin B.-Q.,China University of Mining and Technology | And 8 more authors.
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2011

The mining activity can cause the stress redistribution, and thus generate stress relief and concentration areas, which will greatly affect the gas flow and its control methods. In this paper, the stress distribution and evolution was studied based on numerical simulation. It is indicated that the stress in the O-shaped ring is much lower near the coal seam, and as far away, the stress gradually increases while the O-shaped ring shrinks increasingly. When the coal face was 96 m wide, the mining activity will result in stress relief in the range of 40 m above and 20 m below the coal seam. Therefore, the rock mass was classified into four kinds according to the stress states which were re-compacted, stress relief, stress concentration and original stress zones from inside to outside, respectively. The four zones described the stress distribution and provided a theory basis for gas control. Source


Yang W.,China University of Mining and Technology | Lin B.-Q.,China University of Mining and Technology | Qu Y.-A.,Hancheng Mining Co. | Li Z.-W.,China University of Mining and Technology | And 3 more authors.
International Journal of Rock Mechanics and Mining Sciences | Year: 2011

Mining of the upper protective coal seam is widely practiced in China for coal mine safety, but relief gas may present a new risk of blasting. To control the relief gas effectively, a strain-soften model was built by FLAC3D software to investigate the stress evolution during the process of mining the upper protective coal seam. The results show that the abutment stress changes rapidly within 10m in front of the coal face, and the maximum abutment stress is approximately twice the original when the coal seam is mined 20-30m. The abutment stress should break the rock mass and cause the gas to flow easily. In the stable mining period, the change trends of the x-stress and z-stress are different, and these should also pre-break the rock mass. The stress distributions of the rock mass at different distances under the protective coal seam are different, especially near the coal face, which should greatly affect the gas flow when the space of the protective and protected coal seams change over a large range. The relief angle also changes over a large range, increasing to a maximum approximately 30m behind the coal face, and it decreases gradually when it is far away from the protective coal seam. The results are helpful for designing the coal face of protected coal seams and borehole layouts to control the relief gas. © 2011 Elsevier Ltd. Source


Yang W.,China University of Mining and Technology | Lin B.-Q.,China University of Mining and Technology | Qu Y.-A.,Hancheng Mining Co. | Zhao W.-Q.,Hancheng Mining Co. | And 2 more authors.
Advanced Materials Research | Year: 2011

This paper points out that the coal-bed methane can not only cause gas outburst and explosion, but is also the greenhouse gas. At the same time, methane is un-renewable clean energy. In order to exploit methane effectively, the numerical simulation method was used to investigate the stress distribution and evolution during the process of mining the upper protective coal seam. The results match well with the filed experiment. The result revealed that the stress drops significantly and the cracks are much more developed in the "core stress relieved area" within 10 m in front of the coal face and -30 m behind the coal face, where the methane extraction concentration is usually more than 60%. The results have important significance on methane exploitation. © (2011) Trans Tech Publications. Source

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