A new cable truss support system for coal roadways affected by dynamic pressure

The support of coal roadways is seriously affected by intense dynamic pressures. This can lead to problems with large deformation of the roof and the two side walls of coal roadways. Rapid convergence of the walls and roof, a high damage rate to the bolts and cables, or even abrupt roof collapse or rib spalling can occur during the service period of these coal roadways. Analyzing the main support measures used in China leads to a proposed new cable truss supporting system. Thorough study of the entire structure shows the superiority of this design for roadways suffering under dynamic pressure. A corresponding mechanical model of the rock surrounding the cable truss system is described in this paper and formulas for calculating pre-tightening forces of the truss cable, and the minimum anchoring forces, were deduced. The new support system was applied to a typical roadway affected by intensive dynamic pressure that is located in the Xinyuan Coal Mine. The results show that the largest subsidence of the roof was 97 mm, the convergence of the two sides was less than 248 mm, and the average depth of the loose, fractured layer was only 6.12 mm. This proves that the new support system is feasible and effective.