The composite support technology for soft rock roadway with large loose zone

Aiming at the deformation and failure of mining roadway in Chahasu coal mine, based on engineering mechanics theory of soft rock and loosen circle theory, the loose zone of surrounding rock was observed on site and the reason of roadway surrounding rock structure instability were analyzed, a composite support system is developed in order to combines the advantage of four support methods, achieve partition cooperative supporting and coupling strengthening effect. The results show that: the roadway was influenced unavoidably with the limitation of its own soft rock condition and led to expansive destructive bottom heave, and due to stability of the pillar itself is insufficient, the fissures and cracks increased continuously at the surface and deep of coal pillar which caused by mining disturbance, and finally leading to floor heave with flexural fold. The loosen zone of the coal roadway sides is belonging to the typical large loosen zone. It can substantially strengthen capacity for active supporting by using deep anchor support; improve the self-bearing capacity by optimizing the pillar size and grouting in shallow rock. And it can realize multi-zone cascade bearing and overall strengthening on the roadway surrounding rock by using the compound support technology which using both “passive and active support” and coupled strengthen supporting technology.