采空区底板不同深度岩体裂隙演化规律

    Fracture Evolution Law of Rock Mass at Different Depths of Floor in Gob

    • 摘要: 为研究采空区底板不同深度岩体裂隙演化规律,首先探讨了工作面推进过程中底板不同位置的垂直应力和水平应力分布情况,工作面推进工程中,水平应力变化程度较小,垂直应力变化显著,变化程度远大于水平应力,底板应力也变化显著,其中围压基本保持不变,轴压会随工作面推进呈现先增大后变小的趋势,并可能减小到0,甚至使轴压由压应力变成拉应力;以杏花矿为背景,通过UDEC数值模拟软件得到了底板不同深度裂隙倾角分布规律,底板深度与裂隙数量的关系,结果表明:煤层开采后底板裂隙数量随底板深度增加而减小,直至不再发育;底板浅部以倾角较小的拉张裂纹或Ⅱ型剪切裂纹为主,深部以倾角较大的压剪扩展裂纹为主。

       

      Abstract: In order to study the evolution laws of rock mass fracture at different depths of gob floor, firstly, the vertical and horizontal stress distribution at different locations of floor are discussed with the advancing of working face. During the advancement of the face, the vertical stress changes a lot compared with horizontal stress which changes a little, overall, the change process of floor stress can be regarded as: the confining pressure is constant, the axial pressure increases first and then decreases, and may reduce to zero or even change the axial pressure from compressive stress to tensile stress. Then taking the Xinhua Coal Mine as an example, the distribution laws of crack angle at different depths of floor and the relationship between floor depth and fracture number are acquired through UDEC simulation software, the results show that the number of fractures in the floor decreases with the depth of the floor until it is no longer developed. The cracks in the shallow depth are mainly with small angle or Ⅱtype shear crack, and the cracks in the large depth are mainly shear-expansion with lager angle.

       

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