Prevention measures for support crushing while mining out the upper coal pillar in close distance shallow seams

Aiming at the universal support crushing disasters during mining out the upper coal pillars in close distance shallow seams,the prevention measures for the disaster were proposed on the basis of the inherent mechanism of the support crushing by theoretical analysis and simulation experiments.The results showed that,while mining out the upper coal pillar,the three hinged structure of the key blocks above the coal pillar was unstable,whose relative rotary movement would cause the key stratum structure between the two seams to lose its balance because of overload.Thus the support crushing accident in the mining face jammed.Therefore,the key to the disaster prevention was to regulate the key blocks’ rotary movement.Hereby,the disaster prevention measures of the support crushing were proposed by prompting the key blocks to rotate in advance,preventing and destroying their rotation.All the prevention measures were verified by the similar material simulation experiments with a notable field application effect.