Study On Failure Mechanism And Support Method Of Entry With Soft Interlayer In High Rib

The entry with soft mudstone interlayer causes rib outward dislocation sliding failure in Shendong mining area. It also shows a threat to the safety of production. At present, there is little research involved in this condition. Failure mechanism and supporting countermeasure research has became the new research subject. Therefore, it has important significance to research and solve the problem.Based on the research project of entry and coal pillar supporting technology in Sandaogou mining area, through entry convergence measurement and borehole observation, the vertical cracks in roadway roof is discovered, failure zone of ribs is near the mudstone interlayer and the outer rib is bigger, and the roadway deformation is mainly caused by adjacent mining goaf. Thro ugh the numerical simulation and physical simulation, The self stable equilibrium arch support model of entry with soft interlayer rib is established,and it expounds the importance of strengthen rib support to entry stability and the principle of bolt and cable support design. Based on the principles, the roadway cable and bolt anchor support plan with upper rib long bolt strengthen is put forward and successful in engineering practice.The conclude show that, the outward dislocation sliding is the typical failure characteristic of entry rib with mudstone interlayer in thick coal seam. Roadway deformation is mainly impacted by the lateral abutment pressure of adjacent working face. The mechanism of outward dislocation sliding is concluded as the concentrated stress from adjacent mining goaf causes not only the vertical cracks coming into the roof, but also the horizontal movement of upper rib to adjacent mining goaf. At the same time, key layer pulling structure appeared,the roof takes the upper rib moving to adjacent mining goaf, which forms the outward dislocation sliding of entry rib. According to the asymmetric damage in the roof and rib,established the supporting model of entry with mudstone interlaye. The supporting principal of entry with mudstone interlayer is that “controlling the rib of up and down segmental, adapting and limiting to sliding and strengthen integrality of upper rib”. The design in length of cable is based on the height of self-stable equilibrium arch. Finally, practice has proven that this method haves great supporting effects on the roadway.