大倾角煤层开采覆岩破断机制研究

Study on breaking mechanism of overlying strata in deeply inclined coal seam

为了探究大倾角煤层开采覆岩变形、失稳、破断的演化特征,结合潘二矿1212(3)工作面地质与工程条件,采用数值模拟、物理模拟、理论分析相结合的方法,分析了大倾角煤层开采覆岩变形破坏规律,探讨了巨厚砂岩直覆和无坚硬岩层2种条件下大倾角煤层开采顶板破断失稳形式。研究结果表明:受倾角影响直接顶冒落、滑移,充填下部采空区,基本顶中上部挠度最大而发生断裂,破断裂纹逐渐向基本顶两侧及相邻岩层演化;大倾角煤层倾向岩层间的联动时序性破断是形成非对称拱形承载结构的主因;预裂爆破巨厚砂岩顶板、充填开采软弱岩层工作面可促使关键块体组成的拱形承载结构形成,保证大倾角工作面安全回采。

In order to clarify the evolution characteristics of deformation,instability and breaking of overlying strata in the deeply inclined coal seam,combined with the geological and engineering conditions of the 1212(3)working face in Pan’er Mine,the deformation and failure laws of overlying strata in the deeply inclined coal seam were analyzed by using the combined methods of numerical simulation,physical simulation and theoretical analysis,then the breaking instability forms of roof in the deeply inclined coal seam under two conditions of ultra thick sandstone with direct overlying and without hard strata were discussed.The results showed that affected by the dip angle,the caving and sliding of direct roof occurred and filled the lower goaf.The deflection at the middle and upside of basic roof was the largest and the fracture occurred,then the breaking cracks evolved to both sides of basic roof and adjacent strata gradually.The linkage time sequence breaking between dip strata of deeply inclined coal seam was the main reason for the formation of asymmetric arch bearing structure.The presplit blasting of ultra thick sandstone roof and filling mining of soft strata working face could promote the formation of arch bearing structure composed of key blocks,and ensure the safe mining of deeply inclined working face.