大跨度巷道顶板层面剪切失稳机理及支护方法

Shear instability mechanism and support methods of laminated roof and floor strata in roadway

针对煤层巷道顶板的层状特征,基于梁的受力-变形原理和岩体粗糙结构面剪胀原理,分析大跨度巷道薄层状顶板结构在整个失稳过程中的受力特征和位移特征,揭示了大跨度巷道顶板结构在失稳过程中依次存在两端固定梁结构特征和三铰拱结构特征2个阶段,以及顶板岩层层面相对滑动是导致巷道顶板结构失稳的原因之一;在建立结构平衡条件的基础上给出了顶板基本结构的失稳判别条件;根据失稳判别条件提出了巷道顶板的锚固支护方式及相应的锚固强度计算公式。研究表明:岩层沿层面的滑动是引起巷道顶板岩层结构的失稳原因之一,层面的滑动引起剪胀效应和结构受力效应共同作用引起顶板岩层变形破断以致形成三铰拱结构;当巷道顶板岩层未发生破裂时,巷道顶板支护的重点是提供锚固应力维持层面满足不滑动条件。

Located in coal-bearing strata,the roof of coalmine roadway has the typical characteristics of layered structure. In view of the layered roof,based on the force-deformation theory of beam and shear dilatation theory of strata rough structure,with the combined methods of theoretical analysis,physical simulation and numerical simulation,the paper analyzed the characteristics of force and displacement of roadway roof structure during the whole process of instability,revealed two basic types of modes including fixed beam structural mode with both ends built in and three hinged arch structural mode,revealed roadway roof instability was caused by relative sliding at roof strata interfaces,provided the two basic roof structure instability determination criterion and determining methods of the position of roof instability with different roof structural modes,put forward anchorage support method of roadway roof during different phases and provided the corresponding calculation formulas of anchorage strength. Finally,anti-shear anchorage method of roof strata in roadway was put forward with research results applied into some coalmines.