Study on Mechanism of Rib Spalling in Large Cutting Height Rise Mining Face in Soft Thick Seam

According to problem that the rib spalling easy occurred in the coal wall of the rise mining face of soft thick seam, in order to reveal the spalling mechani sm of the coal wall in the high inclined rise mining face in soft thick seam and to have an effective method to prevent the spalling, an analytical method was applied to a nalyze the spalling mechanics mechanism of the coal wall in the high inclined rise coal mining face in soft thick seam.The numerical simulation method was applied to s tudy the rise mining angle and the mining height affected to the coal wall spalling.The study showed that with the rise mining angle of the seam increaseing, the shearin g failure of the coal wall would be occurred and thus the probability of the spalling occurred would be increased.Under the certain geological conditions, when the seam angle was over 10°，the spalling would be more serious.When the rise mining angle was in a certain condition, with the cutting height increased, the spalling depth woul d be increased.The rational cutting height had a critical value, when the cutting height was over the critical cutting height, the inner failure depth of the coal wall would b e rapidly increased with the cutting height increased.