Support Crushing Mechanism at Longwall Working Face Under Close Distance Room Mining Pillars

For the issues of possible roof pressure and support crushing accidents at 22202 working face in Daliuta Coal Mine, theoretical analysis and numerical simulation were applied to study the mechanism of mining induced stress evolution and support accidents. The result shows that the advanced distance of bearing pressures' peak point will significantly reduce when working face enters into room mining pillar, which causes the superposition of roof stress and advanced bearing peak stress and further prompting considerably growth of the concentrated stress. When the working face is below the coal pillar, roof weighting and stress concentration contribute to support crushing accidents. On the edge of the coal pillars of mining gob, instability of roof movement can not lead to support crushing accidents. When the working face is away from the edge of the mining gob, the support crushing accidents will happen periodically because of the obviously periodical roof pressure.