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松软低渗突出煤层水力冲孔卸压增透研究OACSTPCD

Research of pressure relief and permeability improvement of hydraulic punching in soft and low permeability outburst coal seam

中文摘要英文摘要

针对松软低渗突出煤层瓦斯治理难题,提出水力冲孔物理改性强化增渗瓦斯治理技术.采用理论计算、FLAC3D数值模拟方法对不同钻孔间距条件下孔洞周围煤体的塑性破坏特征进行了分析,对应力演化特征进行了量化表征.研究表明:水力冲孔后孔洞间煤体x向应力明显降低,距离孔洞越近,降低幅度越大;y向应力影响范围与塑性破坏区域范围相当;z向应力峰值应力出现了明显的升高,随着钻孔间距的减小,垂直应力曲线由双峰曲线演化为单峰曲线;孔洞空间为煤体卸压提供了自由面,能够卸除围压,集中应力向孔洞间煤体转移.其后,基于瓦斯煤体渗透率与三向应力和瓦斯压力之间的关系,对不同钻孔间距条件下渗透率演化特征进行了量化表征,孔洞周围煤体渗透率与原始煤体相比大幅提高,促进瓦斯解吸和流动,并确定了合理的钻孔布置间距.现场试验表明:水力冲孔增大了松软煤体暴露面积、为煤体提供卸压增透空间,高负压抽采支管瓦斯流量和浓度明显提升,考察评价单元瓦斯抽采纯量在 6.20~9.8 m3/min范围内波动,瓦斯抽采体积分数在 34%以上.

In response to the difficult problem of gas control in soft and low permeability outburst coal seam,gas control technology is proposed to use physical modification hydraulic punching to improve permeability.Theoretical calculations and FLAC3D numeric-al simulation methods were used to analyze the plastic failure characteristics of coal bodies around holes under different drilling spa-cing conditions,and the corresponding stress evolution characteristics were quantitatively characterized.After hydraulic punching,the radial stress of coal bodies between holes significantly decreased,and the closer they were to the holes,the greater the reduction;the influence range of tangential stress is equivalent to the range of plastic failure zone;the peak vertical stress showed a significant increase,and as the spacing between boreholes decreased,the vertical stress curve evolved from a bimodal curve to a unimodal curve;it was found that the pore space provides a free surface for coal unloading,which can remove the confining pressure and trans-fer concentrated stress to the coal between the pores.Subsequently,based on the relationship between gas coal permeability and three-dimensional stress and gas pressure,the evolution characteristics of permeability under different drilling spacing conditions were quantitatively characterized.Compared with the original coal,the permeability of the coal around the holes was greatly increased,which promoted the gas desorption and flow,and determined the reasonable spacing of the holes,and a reasonable drilling spacing was determined.Field experiments have shown that hydraulic punching greatly increases the exposed area of soft coal bodies,provides pressure relief and transparency space for coal bodies,gas flow and concentration is significantly increased in high negative pressure extraction branch pipes,and the pure gas extraction volume fluctuates within the range of 6.20-9.8 m3/min.The gas concen-tration is above 34%.

张帅

瓦斯灾害监控与应急技术国家重点实验室,重庆 400037||中煤科工集团重庆研究院有限公司,重庆 400037

矿山工程

水力冲孔卸压增透塑性破坏特征应力演化渗透率演化

hydraulic punchingpressure relief and permeability improvementplastic failure characteristicsstress evolutionper-meability evolution

《煤矿安全》 2024 (003)

66-72 / 7

国家自然科学基金青年科学基金资助项目(52204261)

10.13347/j.cnki.mkaq.20230937

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