Deformation mechanism, control principle and technology of soft half coal rock roadway

The large deformation characteristics of half coal rock roadway in Dongsun Coal Mine was found through a large number of deformation survey. The deformation occurred mainly on two sides of the roadway especially at the lower part of the sides. The rock fractures were inspected and the laboratory tests were conducted. The roadway rocks were found to have low strengths, to swell and even to be disintegrated by water and to have the diameter of loosen circle about 4 m. The main reasons for the damage of rock-coal roadway and the instability and the failure of roadway support were found to be the lower strength of rock and the developed rock joints and fissures(under the action of the external environment and disturbance) leading to the expansion and crushed deformation together with the stress superposition and rock creeping leading to the large deformation. A supporting system with the anchor, nets, cables and beams around key structures of the truss and anchor rope was proposed according to the roadway supporting principle. Theoretical analysis shows that the side supporting, namely the truss and the anchor rope are very important in transmitting forces and increasing the force carrying area of two side coal walls and thus improving support capacity. A buckle device was designed based on the mechanical characteristics of the truss, the anchor rope and the coal and rock deformation, which can improve the capacity of bending resistance of truss and anchor rope. The application of the system showed that it could stabilize the side wall, strengthen the roof and restrain the floor heave etc. to achieve an overall improving of the stability of roadway.