The dense conventional combined support hardly controls the overall subsidence of the roadway roof in extra-thick coal seam and affects the excavation efficiency, leading to the technical problem of mining proportion imbalance in the mine. In this study, the typical mining roadway with extra-thick coal seams in the Yanzhou mining area was taken as the engineering background, the roof stress distribution of the development face during the extra-thick coal seam mining was simulated, the deformation and failure characteristics of the roof at different layers under different thicknesses of the top coal were analyzed, and the progressive fragmentation and discontinuous deformation and failure mechanism of the top coal were revealed. Furthermore, the reinforced support technique of the thick anchorage and high preload in roof was put forward，and the reinforced technique was successful applied in the typical roadway in of Baodian Coal Mine, the experimental results showed that the fracture damage of the top coal in the mining roadway was effectively controlled, the deformation of the surrounding rock under the proposed support scheme was reduced by 40 %-50 % and the excavation speed was increased by 33 %.
Keywords: Bearing structure; Discontinuous failure; High preload; Thick anchorage; Thick top coal.
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