叠合采动下围岩破坏区非均匀扩展机理及巷道稳定控制

Mechanism of non⁃uniform expansion and stability control in surrounding rock failure zone due to superimposed mining

为揭示叠合采动影响下围岩的变形破坏特征,以羊场湾矿160206工作面为工程背景,通过现场监测、理论分析计算、数值模拟和现场工程试验的综合研究方法,研究叠合采动应力场下回风巷围岩的应力场演化规律和塑性区形态分布特征,揭示煤层巷道在叠合采动影响下的非均匀扩展机理。结果表明:上下区段的叠加采动影响导致160206工作面前方回风巷处于高偏应力环境,这是造成回风巷发生非对称破坏的主控因素;叠合采动巷道在高偏应力作用下塑性区呈蝶形形态,且蝶叶向采空区一侧偏转,围岩塑性区形态呈煤壁帮顶板及煤柱帮底板破坏范围大的非均匀扩展特征。据此,提出采用非对称长短锚杆索协调加强支护、超前单元支架及钻孔卸压的联合支护技术,在叠合采动影响区域进行工业性试验,取得良好的效果。

In order to reveal the deformation and failure characteristics of surrounding rock under the influence of superposed mining,comprehensive investigations including field monitoring,theoretical analysis&calculation,numerical simulation and field trial were carried out in 160206 working face of Yangchangwan Mine.The stress evolution field and the plastic zone distribution characteristics of surrounding rock in return airway under superimposed mining⁃induced stress field were studied,and the non⁃uniform expansion mechanism of coal roadway under superimposed mining was revealed.The results indicated that a high deviatoric stress environment of the return airway in front of the 160206 working face could be incurred by the superimposed mining effect of the upper and lower mining district sublevels,which was the main controlling factor for the asymmetric failure of the return airway.The plastic zone of the roadway under superimposed effect expressed a butterfly⁃like pattern under the high deviatoric stress,and the butterfly leaf deflected to the goaf side.Non⁃uniform expansion characterized by expansive failure scope at the rib⁃side roof and pillar⁃side floor could be noticed in the plastic zone of the surrounding rock.Therefore,combined support technical consisting of coordinated strengthening support by asymmetric long and short cable bolts,advancing unitary chocks,and stress⁃relief boreholes was proposed.The industrial trail in a site impacted by the superimposed mining demonstrated favorable results.