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Comparing to the roof and door, the two ribs of coal mine roadways are relatively weaker and have more deformability. The large deformation of the coal-mass in the ribs have significant effect on the roadway stability. Based on the practical case of severely deformed ribs and by considering its deformability, an analytical model of roof beam with Winkler foundation is built. Hereby the characteristics of bending moment and reflection have been studied. The foundation rigidity of coal mine roadway is revealed and the rib-control support principle is proposed. By employing reinforcement in the ribs, the foundation rigidity of the ribs will increase, and the deformation and failure of the ribs will directly controlled by the reinforcement. The stability of roof and floor is reinforced via the foundation rigidity effect. The foundation rigidity and the rib-control support principle of coal mine roadway are analyzed and validated by means of numerical simulation and field tests. The results show that under the effect of the vertical concentrated stress over ribs, the coal-mass is notably compressed and the roof strata bend and sag along with it. The foundation rigidity has great effect on roof deformation which makes it the key influencing factor. Under the conditions of identical roof support, the reinforcement in the ribs will not only reduce the convergence and failure extent of the ribs during roadway development and retreat mining, but also effective control the deformation and failure of the roof and the floor, which makes it an effective method to improve the roadway stability. This study has improved the understanding of the importance of rib support in roadway ground control, and revealed the support mechanism of rib-control. [ABSTRACT FROM AUTHOR]

In view of the asymmetrical deformation failure in the mining roadway at a steeply inclined special thick coal seam, some field observations, mechanical modeling calculations and numerical simulation analysis were used to reveal the asymmetrical deformation failure mechanism after the excavation of the roadway in steeply inclined coal seams. The stress field after the excavation of the roadway and the distribution characteristics of the plastic zone were analyzed. A new support and reinforcement scheme for the retractable U-shaped steel and asymmetric prestressed anchor(cable)support was proposed. The study shows that:(1) the asymmetrical failure of the roadway is characterized by the subsidence, slippage, and internal expansion along the bedding of the hard rock strata along the side of the coal body; the subsidence of the top of the side of the hard rock is greater than that of the coal side and the central axis of the roadway inclines to the coal side. (2) The asymmetric deformation mechanism of the roadway is that, under the effect of nonuniform load, the angle and size of the counterforce of the shoulder angle support on both sides of the roadway arechanged. The reaction force of the hard rock lateral support is greater than that of the coal side. Also the inclination angle of the coal side is larger than the side of the hard rock. The side rock of the hard rock layer slides, sinks, and expands along the bedding under the action of small angle and large stress, and the side of the coal body is pushed out of the drum under the action of nearly vertical angle force. (3) The bending moment of the roadway from the side of the hard rock to the side of the coal body is increasing all the time. The shear force appears to increase first, then decrease and then increase, and the direction changes in the second increase. The position of the direction change is the offset position of the roadway axis inclining to the side of the coal body. The axial force appears as a parabola,decreasing first and then increasing. The optimum and reasonable section of the roadway under non-uniform load acts is the"asymmetric three-hinged arches". (4) The retractable U-shaped steel and asymmetric prestressed anchor(rope) support are proposed, focusing on reinforcing the lateral support of the roadway coal body and the top support on the side of the hard rock. [ABSTRACT FROM AUTHOR]