Analysis on Hydraulic Support Crushed Mechanism When Fully-Mechanized Coal Mining Face Passed Through Concentrated Coal Pillar Area in Above Seam

In order to solve the hydraulic support crushed accident occurred when a fully-mechanized coal mining face passed through concentrated coal pillar area in above seam, a theoretical analysis and a site mine pressure observation method were applied to analyze the causes of the hydraulic support crushed accident when No.22301 fully-mechanized coal mining face passed through the coal pillar concentrated area in above seam in Shigetai Mine. The paper revealed the mechanism of th e hydraulic support crushed accident and provided the relevant prevention countermeasures. The results showed that when coal mining face passed through the conce ntrated coal pillar 5 ~ 20m, the overburden strata would be broken at the boundary of the concentrated coal pillar and a lined beam type articulated structure would be f ormed. With the coal mining face pushed forward, the articulated structure formed with the broken rock blocks would have a stability lost by a further rotary movement. Thus an impact role would be occurred to the coal mining face in the low seam, a dynamic mine pressure phenomenon would be easily occurred and a hydraulic suppor t crushed accident would be caused. Therefore the paper provided the measures of the optimized mining design of the coal mining face, pre-fracturing blasting on the C oncentrated coal pllars in the above seam, inclination adjustment of the coal mining face, mine pressure observation and others, the fully-mechanized coal mining face could be kept away from the influences of the stress concentration, the periodical pressure strength was reduced and the dynamic mine pressure was reduced. Finally, t he target to avoid the hydraulic support crushed accident was realized.