【作者】 刘海波；

【导师】 程远平；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2009， 博士

【摘要】 本文在理论分析的基础上,利用相似材料模拟试验、数值模拟和现场试验相结合的研究方法,系统研究了极薄保护层钻采过程中上覆煤岩体移动变形、被保护煤层采动裂隙发育及分布特征、被保护煤层地应力变化及煤层顶底板变形、煤层透气性变化及分布、被保护煤层卸压瓦斯流动规律及在卸压瓦斯抽采中的应用,其研究成果对解决类似采矿地质条件下的煤与瓦斯突出防治及深部安全开采问题有重要实际意义。研究表明,崔庙煤矿二1煤层具有强突出危险性,二1煤层消除突出危险性必须将瓦斯压力降至0.32MPa以下或者瓦斯含量降至8m3/t以下。针对崔庙煤矿特殊的采矿地质条件和二1煤层具有低透气性、高瓦斯和强突出危险性的特点,提出采用螺旋钻采煤机钻采极薄保护层一9煤层结合上覆二1煤层卸压瓦斯强化抽采的区域性瓦斯治理方法。利用煤层采动瓦斯渗透性模拟试验台对极薄保护层钻采上覆被保护煤层地应力、煤层变形和煤层透气性变化及分布进行试验研究。结果表明,在极薄保护层钻采过程中上覆煤岩体产生整体弯曲下沉,没有冒落带和明显的断裂带。被保护煤层位于弯曲下沉带,由于采动作用在煤层中产生大量顺层张裂隙,被保护煤层与保护层之间没有形成明显的垂直连通裂隙。被保护煤层地应力大大降低,在充分卸压区实测煤层顶底板膨胀变形为10.5mm,相对变形为1.31‰。通过相似模拟试验验证了气体在煤层中的流动规律符合达西定律,并研究得出极薄保护层钻采前后被保护煤层透气性变化及分布特征。数值模拟研究表明,被保护煤层在受保护区域地应力平均为3.4MPa,比原岩应力下降32%。在充分卸压区煤层顶底板膨胀变形为11mm,相对变形为1.4‰。随着保护层工作面向前钻采,被保护煤层顶底板变形呈现压缩、快速膨胀、膨胀变形减小到稳定的变化规律。同时研究表明,极薄保护层采高对被保护煤层的卸压膨胀变形有很大影响。采用RFPA数值模拟软件对极薄保护层钻采上覆被保护煤层透气性变化和卸压瓦斯流动及瓦斯抽采规律进行模拟。研究表明,极薄保护层钻采后被保护煤层透气性急剧增大,比原始煤体透气性增大407倍。在煤层中形成了卸压瓦斯“解吸-扩散-渗流”的活化流动条件,卸压瓦斯在被保护煤层的顺层张裂隙中流动。同时研究表明瓦斯抽采穿层钻孔周围的瓦斯压力随极薄保护层工作面推进距离和抽采时间的增大而有明显降低。现场试验研究表明,采用极薄保护层钻采结合卸压瓦斯强化抽采的区域性瓦斯治理方法后,在试验区二1煤层的瓦斯压力由0.75MPa降为0.15MPa,瓦斯含量由13m~3/t降为4.66m~3/t,煤层顶底板膨胀变形为12mm,相对变形为1.5‰,煤层的透气性系数由0.047m~2/MPa~2·d增加到18.928m2/MPa~2·d,提高了403倍,瓦斯抽采率达到64%,二1煤层已经全面消除煤与瓦斯突出危险。同时研究表明,理论分析、相似材料模拟试验、数值模拟和现场试验研究得到的结论具有很好的一致性。更多还原

【Abstract】 Based on the theory analysis, with the colligation analysis method of the similar material simulation test, the numerical simulation and the field test, movement and deformation of the overlying coal-rock mass, the mining-induced fractures growth and distribution feature of the protected coal seam, the change of ground stress and deformation of the protected coal seam, the permeability change and permeability distribution of the coal seam, the rule of pressure relief gas flow, and its application in pressure relief gas drainage are studied systematically. The results have an important significance for solving problems of outburst prevention and deep safe mining in the similar mining geological conditions.The results show that, coal seam No.21 is the strong outburst dangerous coal seam in Cuimiao Coal Mine and the gas parameters of eliminating outburst must be controlled below 0.32MPa or 8m3/t. According to the special mining geological conditions and coal seam No.21 with low permeability, high gas concentration, and strong outburst risk, we present the regional gas control technique of the extra-thin protective coal seam drilling combined with pressure relief gas drainage of the protected coal seam used by the coal auger.Ground stress, deformation, and permeability change and permeability distribution of the overlying protected coal seam induced by drilling the extra-thin protective coal seam are studied used by the seam mining and gas permeability simulation test-bed. The results show that, the overlying coal-rock mass is integrally bending and sinking, without forming any caving zone and the obvious fault zone. The protected coal seam is in the bending zone, a large number of bed separation crannies are created induced by mined, and the obvious vertical joint crannies are not created between the protected coal seam and the protective coal seam. Ground stress of the protected coal seam decreases in a great degree. Measured expansion deformation value in the full stress-relaxed area of the protected coal seam is 10.5mm and the relative expansion deformation is 1.31‰. Gas flow regularity accords with Darcy law in the protected coal seam, which is verified by the test, and then the rule of permeability change and permeability distribution of the protected coal seam is studied.The numerical simulation results show that, the average value of ground stress in the full stress-relaxed area of the protected coal seam is 3.4MPa, which decreases 32% compared with the original ground stress. The expansion deformation is 11mm and the relative expansion deformation is 1.4‰. The deformation of the protected coal seam is characterized by 1) compression, 2) rapid expansion, and 3) reaching a stable expansion value. The results show that, mining height of the extra-thin protective coal seam has a great influence on the ground stress and expansion deformation of the protected coal seam. The change rule of the seam permeability, pressure relief gas flow, and gas drainage rule of the protected coal seam are studied used by RFPA. The results show that, the extra-thin protective coal seam drilling makes the seam permeability improve rapidly, increasing by 407 times compared with the original permeability. The pressure relief gas flow condition is formed which is desorption, diffusion, and percolation. Gas flows in the open crannies along the protected coal seam. Gas pressure around a penetration borehole through the protected coal seam obviously decreases with the increase of mining distance and the drainage time.The results of the field test show that, used by the method of the extra-thin protective coal seam drilling combined with pressure relief gas drainage, the gas pressure of coal seam No.21 decreases from 0.75MPa to 0.15MPa, the gas content decreases from 13m³/t to 4.66m³/t, the expansion deformation is 12mm, and the relative expansion deformation is 1.5‰. The permeability coefficent increases from 0.047m²/MPa²·d to 18.928m²/MPa²·d, increasing by 403 times, the gas drainage rate is up to 64%, and the outburst risk of the protected area in coal seam No.2₁ is eliminated. In addition, the results obtained by the method of the theory analysis, the similar material simulation, and the numerical simulation are well fit to the results of the field test.更多还原