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穿层钻孔喷孔周围煤体应力与变形数值模拟研究

Study on Numerical Simulation of Coal Stress and Strain Around Blowout Borehole Drilled Through Strata

  • 摘要: 依据煤与瓦斯突出机理,在全面分析低透气性突出煤层穿层钻孔喷孔原因及其煤体移动变形基础上,利用FLAC3D软件及相关理论对喷孔孔洞周围煤岩体的应力场分布规律、位移场分布规律等进行数值模拟研究。研究表明,在突出孔洞形成后,孔洞周围煤体内形成卸压区、破裂区、弹性应力区,煤体内部裂隙萌生、扩展、贯通,周围煤体产生指向孔洞中心的径向位移,位移大小与喷孔孔洞距离、蠕变煤体对后续煤体的流变变形的阻碍卸压有关;喷孔的影响范围与喷孔孔洞半径、煤层埋藏深度、煤层厚度正相关;卸压质量比与喷孔空洞半径正相关,与煤层埋深负相关。

     

    Abstract: According to the mechanism of the coal and gas outburst, based on a full analysis on the cause of the blowout borehole drilling through the low permeab ility seam and the coal moving deformation, a FLAC3Dand a related theory was applied to the numerical simulation study on the stress field distribution law, the displac ement filed distribution law and others of the coal and rock around the blowout borehole. The study showed that when the blowout borehole formed, in the coal around t he blowout borehole, there would be a pressure released zone, fracturing zone and elastic stress zone. The cracks would be produced, expended and connected within coal. The radial displacement forward to the borehole center occurred in the coal around the borehole, the displacement size and the distance of the displacement to th e blowout borehole, creep coal would be related to the blocking and pressure releasing of the coal rheology deformation in the later sequence. The influence scope of t he blowout borehole would be a positive correlation to the radius of the blowout borehole, the depth of the seam buried and the thickness of the seam. The pressure rel easing quantity would be a positive correlation to the radius of the blowout borehole and a negative correlation to the depth of the seam buried.

     

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