Research on Pressure-Relief Effort of Mining Upper-Protective Seam on Protected Seam

Abstract

Abstract Based on the mining and geological conditions in No.12 Mining District of Jining No.3 Coal Mine, the variation laws of stress and deformation of the lower-protected seam along with the mining operation of upper-protective seam are studied by numerical simulation and field test in this paper. The results show that the distribution of in situ stress in protected seam is changed correspondingly during the protective seam mining. While mining the protected seam, the vertical stresses around the protected seam experienced three stages: stress increasing before mining, decreasing after mining and stepwise steady stage. In addition, the protective seam mining can also cause expansive deformation in protected seam and its surrounding rock, destroy the strata structure and release the elastic energy in advance, thus reducing the rock burst risk in protected seam. The results of numerical analysis and the field monitoring results are basically in agreement. The study in this paper will provide theoretical basis and practical value for reasonable design and safety mining of coal seams with rock burst propensity.