倾斜煤层沿空煤柱合理宽度确定与稳定机制分析

Determination of reasonable width and stability mechanism of coal pillar in inclined coal seam

为探究倾斜煤层中沿空掘巷煤柱合理宽度,分析煤柱稳定机制,基于FLAC~(3D)模拟分析了不同煤柱宽度的沿空掘巷数值模型。结果表明:沿空煤柱宽度不同,巷道围岩及煤柱破坏模式存在差异;缓倾斜煤层中沿空掘巷和采空区围岩变形分布总体上呈现采空区中间大两侧小的变化趋势,且呈现非对称变形特征;煤柱宽度增大,煤柱应力分布呈现拉向压应力转换趋势。煤柱宽度≥7 m时,沿空煤柱临近采空区两侧的塑性剪切带脱离沿空掘巷顶部围岩,向采空区转移,煤柱范围内应力分布呈现主压应力特征。煤柱宽度为7 m左右时,沿空煤柱临近采空区跨中变形最大,但缓倾斜煤层沿空掘巷护巷窄煤柱的安全性较高,可有效避免煤柱承载过大,将竖向压力向巷道实体煤侧诱导,达到减小巷道顶板拉伸破坏,将采空区剪切破坏带剥离沿空掘巷道的目的。

In order to explore the reasonable width of cave-along roadway in inclined coal seam and analyze the stability mechanism of coal pillar,the numerical models of cave-along roadway with different widths of coal pillar were simulated and analyzed based on FLAC3D.The results show that the failure modes of roadway surrounding rock and coal pillar are different with different width of coal pillar.In the gently inclined coal seam,the deformation distribution of the surrounding rock along the gob and the gob generally shows a change trend of the large middle and small two sides of the gob,and presents asymmetric deformation characteristics.As the width of the coal pillar increases,the stress distribution of the coal pillar shows a transition trend from tensile stress to compressive stress.When the width of the coal pillar is≥7 m,the plastic shear zone on both sides of the gob near the coal pillar is separated from the surrounding rock on the top of the gob and transferred to the gob,and the stress distribution within the coal pillar shows the characteristics of principal compressive stress.When the width of the coal pillar is about 7 m,the deformation in the middle span near the gob is the largest,but the safety of the narrow coal pillar in the roadway excavation along the gob is high,which can effectively avoid the excessive bearing of the coal pillar,induce the vertical pressure to the solid coal side of the roadway,and achieve the purpose of reducing the tensile failure of the roadway roof and peeling the shear failure zone of the gob along the gob.