钻屑法钻孔周边煤体应力分布规律与变形特征

    The stress distribution law and deformation characteristics of coal around the borehole by the drilling cuttings method

    • 摘要: 钻屑法是预测煤矿冲击危险性的重要方法,钻孔周边煤体的应力分布规律与变形特征直接影响钻屑煤粉量。本文以济宁三号煤矿3煤层为研究对象,采用数值模拟的研究方法,分析单个钻屑法钻孔、2个钻屑法钻孔间距60 cm、3个钻屑法钻孔间距40 cm、6个钻屑法钻孔间距20 cm条件下周边煤体应力、位移和塑性区的变化规律。研究结果表明:单个钻屑法、多个钻屑法钻孔周边煤体均受压应力,钻孔位置处于卸压区,钻孔两侧处于应力增高区,钻孔之间的最高支承压力为原岩应力的1.11倍左右。2个钻孔间距60 cm、3个钻孔间距40 cm时,钻孔之间既存在增压区也存在原岩应力区,钻孔之间增压区的范围分别为0.20 m、0.24 m,钻孔之间原岩应力区的范围分别为0.35 m、0.12 m;6个钻孔间距20 cm时,钻孔之间只存在应力增高区;钻孔之间的增压区范围随钻孔间距的减小而增大,钻孔之间的原岩应力区范围随钻孔间距的减小而降低。钻孔顶部煤体向下移动,底部煤体向上移动,顶部煤体最大位移量在1.30 mm左右,底部煤体最大位移量在1.10 mm左右,钻孔顶部煤体的位移量大于底部。研究成果为煤矿冲击地压的预测与治理提供重要的理论支撑。

       

      Abstract: The drilling cuttings method is an important approach for predicting the risk of rockburst mines. The stress distribution law and deformation characteristics of coal around the borehole directly affect the amount of drilling cuttings. The third lower coal seam of Jining No.3 Coal Mine is the research object. The variation laws of stress, displacement and plastic zone of coal under the conditions of a single borehole, 2 boreholes with a spacing of 60 cm, 3 boreholes with a spacing of 40 cm, and 6 boreholes with a spacing of 20 cm are analyzed by the numerical simulation method. The results show that the surrounding coal of boreholes is subjected to compressive stress. The borehole location is in the stress relief zone. The two sides of borehole are in the stress increased zone. The maximum supporting stress is between boreholes is about 1.11 times the original rock stress. When the drilling spacing is 60 cm and 40 cm respectively, there are original rock stress zone and stress increased zone between the boreholes. The range of stress increased zone between the boreholes is 0.20 m and 0.24 m, respectively. The range of original rock stress zone between the boreholes is 0.35 m and 0.12 m, respectively. When the drilling spacing is 20 cm, there is only a stress increased zone between the boreholes. The range of original rock stress zone decreases with the decrease of drilling spacing. The range of stress increased zone increases with the decrease of drilling spacing. The top of the boreholes moves downward while the bottom moves upward. The maximum displacement of coal at the top is approximately 1.30 mm. The maximum displacement of coal at the bottom is approximately 1.10 mm. The displacement at the top is greater than that at the bottom. The research results provide important theoretical support for the prediction and treatment of coal mine rockburst.

       

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