Mechanism and Control Technology of Coal Pillar Fragmentation at the End of Stress Superposition Zone in Changchunxing Coal Mine
The 307 working face of Changchunxing Coal Mine is affected by multiple concentrated stresses.The tail end coal pillar collapses seriously,the roof of the stress zone sinks and breaks,and the two-side coal pillars converge,which seriously restricts the safe and rapid advancement of the working face.Through technical research,the fracture mechanism of surrounding rock in the end area is analyzed.Accord-ing to the production status,the combined support technology of pressure relief support+flexible grouting+self-moving steel shed is adopted for the surrounding rock in the end area.The practical application shows that after the combined support technology is adopted,the suspended roof area in the end area is reduced to 1.2 m2,the caving length of the end coal pillar is reduced to 0.8 m,the roof subsidence of the return air crossheading within 30 m ahead is reduced to 0.13 m,and the convergence of the two sides is reduced to 0.21 m.The support effect is obvious.
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