Mining-induced stress evolution mechanism and control technology of working face in deep coal seam bifurcation and merging area: a case study

The strong mine pressure disaster easily induced by the high stress concentration area of deep coal seam bifurcation and merging area (CSBMA). Zhangshuanglou Coal Mine was selected as the research site. Theoretical analysis, physical and numerical simulation and field measurement was adopted to study the evolution law and control technology of mining-induced stress in the deep CSBMA. The main conclusions are as follows: (1) from the bifurcation area to the merging area, the peak value of the front abutment pressure decreases first and then increases slightly to a stable evolution law with the gradual decrease of the coal seam spacing. From the merging area to the bifurcation area is the opposite. (2) The coal seam spacing of the bifurcation area is 7.5–25 m, which is the area where the peak value of the front abutment pressure increases. The maximum peak value is located at the junction of the normal area and the bifurcation area, and the stress concentration coefficient is about 2.1. (3) After the control technology of coal seam water injection softening is adopted for the high stress concentration area, the maximum peak stress concentration coefficient is reduced to about 1.6, which effectively reduces the stress concentration degree. The evolution law of mining-induced stress in the deep CSBMA provides guidance for the prevention and control area of strong mine pressure disaster in this area, and ensures the safe mining of working face.