Pattern of Influence of the Mining Direction of the Protective Seam on the Stress of the Surrounding Rock

Abstract

The maximum principal stress of the original rock has obvious directionality, and the pressure relief effect is different when the protective seam is mined along different directions. In this paper, the Fast Lagrangian Analysis of Continua (FLAC3D 6.0) numerical simulation software was used to establish a numerical calculation model according to the actual stratum conditions of the Pingdingshan No. 8 Coal Mine. The distribution and evolutionary characteristics of three-dimensional stress and three-dimensional displacement of the stope are studied under the condition that the mining direction of the protective seam is parallel to or vertical to the maximum principal stress direction of the original rock; the pattern of influence of the mining direction on the pressure relief and outburst prevention effect of the protective seam mining is analyzed. For the protective seam, the maximum principal stress in the coal in front of the protective seam cut–hole is significantly reduced, and the outburst potential is reduced in parallel mining. However, in vertical mining, the maximum principal stress in the coal in front of the protective seam cut–hole increases significantly, and the outburst potential increases. For the protective seam and surrounding rock, parallel mining can more fully reduce the maximum principal stress of the protective seam, reduce the difference in the three-dimensional stress, and effectively reduce the outburst potential of the protective seam. Therefore, parallel mining can not only improve the safety of the protective seam but also improve the pressure relief and outburst prevention effect of the protective seam. This conclusion is verified by the outburst prevention effect of the parallel mining of the remote upper protective seam in the Pingdingshan No. 8 Coal Mine. The research results are helpful for optimizing mine outburst potential prevention and control work from the aspect of mining layout. Through parallel mining, the outburst potential of the mine can be effectively reduced overall.