大间距煤柱与采动叠加影响下煤层应力演化及应用

    Coal seam stress evolution and its application under the influence of large spacing coal pillar and mining superposition

    • 摘要: 选取平煤八矿己15-22080工作面作为研究对象,通过FLAC3D数值模拟方法分析了采面应力演化特征,对瓦斯治理区域进行了分区划分。研究结果表明:在大间距丁组煤柱叠加戊组煤层开采影响下,工作面应力分布存在较大差距;应力集中现象分布于整条机巷,距机巷外口150~500 m范围内尤为严重,垂直应力最大值为27.5 MPa,增加了8 MPa;工作面靠近风巷一侧存在卸压区,最大卸压达10 MPa;应力增加使得煤体裂隙率最大降低约29 %,渗透性最大降低约64%;在高应力叠加区煤层瓦斯压力梯度增大,煤体渗透率降低,突出危险性更大;相反,卸压区内煤层渗透率增加,突出危险性更小;根据工作面不同区域突出危险性的不同,将工作面分为一般突出危险区、中等突出危险区与重度突出危险区。

       

      Abstract: The Ⅵ-22080 working face of Pingmei No.8 mine was selected as the research object. Through FLAC3D numerical simulation method, the stress evolution characteristics of the working face were analyzed, and the working face was divided into regions. The results show that the stress distribution of working face has a great difference under the joint influence of large spacing coal pillar of group Ⅳ coal seam and the coal seam mining of group Ⅴ coal seam. Stress concentration phenomenon is distributed in the whole haulage roadway, especially in the range of 150 m to 500 m from the outer entrance of the roadway. The maximum vertical stress of the roadway is 27.5 MPa, increased by 8 MPa. There is a pressure relief zone near the air-return roadway of the working face and the maximum pressure relief degree is 10 MPa. With the increase of stress, the fracture rate and permeability of coal decrease by 29 % and 64% respectively. In the high stress superimposed area, the gas pressure gradient increases, the permeability of coal body decreases, and the outburst risk increases. On the contrary, the permeability of coal seam in the pressure relief zone increases, and the outburst risk is smaller. According to the difference of outburst risk in different areas of working face, the working face can be divided into general outburst risk area, medium outburst risk area and severe outburst risk area.

       

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