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Effects of Key Stratum Location on Hydraulic Conductivity Fracture Zone

The hydraulic conductivity fracture zone is the main channel causing inrush disaster in mine. This paper makes a few analysis on the effect of the location of primary key stratum through the theoretical analysis and numerical simulation. The results show that: (1). When the distance from key stratum to coal seam is about 3 times than the height of coal seam, the hydraulic conductivity fracture zone is higher than normal but the caving zone is lower than normal. When the distance from key stratum to coal seam is about 11 times than the height of coal seam, the hydraulic conductivity fracture zone is lower than normal but the caving zone is higher than normal; (2). The effect of Winkler foundation is obvious when the distance from key stratum to coal seam is 7 times than the height of coal seam, more even but the inverse is not; (3). We can certain whether the key stratum is fractured or not according to the hypothetical rock cohesive force expediently.