Supporting strategy for large span intersection in deep soft rock roadway of the Fifth Coal Mine of Hebei Coal Group

The third level deepening roadway of the Fifth Coal Mine of Hebi Coal group located in the syncline axis suffers from severe tunnel deformation and short supply of production due to high tectonic stress and strong disturbance of the upper working face. Based on comprehensive analysis and mechanical evaluation of the engineering geological conditions around the roadway, the mechanical mechanism of deformation and the failure of the roadway are studied. A new coupling supporting design, bolt-mesh-cable + truss with anchor in floor to control floor heave, is proposed and relevant technology is optimized in accordance with the large span intersection of the new tunnel. The accuracy and reliability of the optimum design is proved by numerical simulation and in-situ monitoring. Practices have proved that the bolt-mesh-cable + truss scheme will make full use of the action of coupling support sufficiently, and bring the self-supporting capability of adjacent rock into full play so as to control the roadway deformation effectively, and provide conditions for safe and efficient production of the mine.