Study on mechanism and application of support in large-section top coal roadway with extra-thick coal seam

The tailentry in first mining face of Ⅱ₃ coal seam in Lingdong coal mine is a large-section top coal roadway with extra-thick coal seam, and the control of roof is difficult.The characteristics of top coal are studied comparatively by in-situ and lab test, which reveals that the strength of the top coal is low, the fractures are well developed, and the strength of the shallow coal decreases obviously.The numerical simulation shows that by using large size of bolt surface protecting components, the prestresses could diffuse actively in seam and the effective compression stress zone could formed in surrounding rocks.Field test in the tailentry of first mining face indicates that the integrity of top coal integrity is well maintained, and the deformation of roadway surrounding rocks is effectively controlled.Excellent supporting effect proves that this system might provide effective supporting approach for similar roadways.