Bearing mechanism of roof and rib support structure in automatically formed roadway and its support design method

Non-pillar mining technology with automatically formed roadway is a new mining method without coal pillar reservation and roadway excavation. The stability control of automatically formed roadway is the key to the successful application of the new method. In order to realize the stability control of the roadway surrounding rock, the mechanical model of the roof and rib support structure is established, and the influence mechanism of the automatically formed roadway parameters on the compound force is revealed. On this basis, the roof and rib support structure technology of confined lightweight concrete is proposed, and its mechanical tests under different eccentricity are carried out. The results show that the bearing capacity of confined lightweight concrete specimens is basically the same as that of ordinary confined concrete specimens. The bearing capacity of confined lightweight concrete specimens under different eccentricities is 1.95 times higher than those of U-shaped steel specimens. By comparing the test results with the theoretical calculated results of the confined concrete, the calculation method of the bearing capacity for the confined lightweight concrete structure is selected. The design method of confined lightweight concrete support structure is established, and is successfully applied in the extra-large mine, Ningtiaota Coal Mine, China.