【作者】 王亮；

【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】 在工作面采动影响下,采场围岩应力重新分布,上覆岩层垮落后形成垮落带、断裂带及弯曲带,在一定高度范围内,处于“三带”内的煤层能够获得卸压效应,这对上覆煤岩体内突出煤层的瓦斯治理可以起到积极的作用。本文针对突出矿井处于弯曲带内的远程被保护层(最大相对层间距为43B采高)顶板存在巨厚火成岩(均厚达120m)的特殊地质条件,综合运用实验研究、理论分析、相似模拟、数值模拟等手段,系统研究了保护层开采采场覆岩离层、裂隙的动态演化过程及产生机理、巨厚火成岩的力学特性、上覆煤岩体卸压与变形特征、卸压瓦斯渗流规律等,提出了远程卸压瓦斯的抽采方法,并成功运用到工程实践中,为类似地质条件下的远程保护层开采及卸压瓦斯抽采技术提供了理论依据和参考。其主要创新体现在如下五个方面:1)充分考虑巨厚火成岩的厚度大、强度高的特点,综合巨厚火成岩覆岩载荷与体积力共同作用,建立了巨厚火成岩受力数学模型。同时,采用薄板理论,对其下伏的煤岩体离层产生机理进行了理论分析。综合巨厚火成岩的力学参数实验室分析及模拟试验,得出巨厚火成岩为矿井的主关键层,其破断垮落步距大,控制着上覆岩层的整体运动。2)综合运用数值模拟和相似模拟手段,分析了巨厚火成岩下采动离层、裂隙的动态演化过程及被卸压煤层的变形规律。通过分析发现,在巨厚火成岩的支撑作用下,覆岩形成的大量离层、裂隙能够长期保持不完全闭合,裂隙成为瓦斯流动的通道,离层成为瓦斯的聚集区,弯曲带内的远程被保护煤层卸压均匀,被保护层相对膨胀变形量平均可达28‰,导致其煤层透气性系数增加3000倍以上。3)获得了巨厚火成岩下裂隙演化与瓦斯储运的关系。提出了巨厚火成岩下采动裂隙与离层场呈“帽状”分布特征以及存在断裂带与弯曲带离层区两个瓦斯富集区域的概念;系统地将远距离煤层群卸压瓦斯储集和运移规律与采动覆岩移动、裂隙与离层演化过程有机的结合起来,得出了采动裂隙场与瓦斯流动场耦合规律。4)获得了巨厚火成岩下远程被保护层卸压瓦斯运移规律。采用钻孔抽采卸压瓦斯时,卸压瓦斯首先通过竖向裂隙(或直接)流入离层内,使离层成为瓦斯富集区,瓦斯抽采效果更加明显。通过对现场抽采数据的反算,验证了巨厚火成岩下卸压煤体附近存在离层瓦斯富集区的事实。5)研发了远距离穿层钻孔抽采卸压瓦斯的方法,并在海孜矿成功地进行了试验,取得了显著的抽采效果。稳定期单孔瓦斯抽采量达4m3/min以上,抽采半径达到100m以上。经过一年时间的抽采,保护范围内的卸压瓦斯抽采率达到73%以上,有效地消除了中组煤的突出危险。目前该方法在国内外其他矿井并无应用先例。更多还原

【Abstract】 When a coal seam has been mined, the stress equilibrium around the stope is redistributed, and the caving zone, the fractured zone and the bending zone are formed in overlying strata resulted by collapsing. In certain altitude range, pressure relief effect happens on the coal-rock masses in the“three zones”, which makes a good and active effect to the gas control of outburst coal seams. Based on over 120m extremely thick igneous rock exists above the distant protected layers in the outburst coal mine, we used several methods to research fractures and separations dynamic evolution, the mechanical characteristic, pressure relief characteristic, move deformation, and seep characteristic of overlying coal-rock masses, such as experiment research, theories analysis, similar simulation test, numerical simulation and field application. We still proposed several methods for draining pressure relief gas, and the chosen methods were successfully applied to the practice. The research has an important significance for safety production, and provides theoretical basis and reference for distant protective layer mining technology and pressure relief gas drainage in coal mines with similar geological conditions. The paper’s innovative points are as followed:1)Considering the characteristics on thickness and intensity of igneous rock, combined with the action by rock load and sel-gravity, the mathematical model of the extremely thick igneous rock by forces had been founded. At the same, we analysed the separation producing theories using thin plate theory. The mechanical experiment and numerical simulation tests showed that the extremely thick igneous rock was the main key stratum of coal mine, which had a big broken drawing pace and controlled the whole movement of overlying strata.2)The paper analysed the separations and fractures dynamic evolution and deformation laws of protected layers using similar simulation and numerical simulation tests. The results showed that the separations and fractures could keep open for a long time under the support of the extremely thick igneous rock. The fractures became the channels of gas migration and separations became the enrichment areas of pressure relief gas. The pressure relief effect was equal to the protected layers, the average value of relative expansion deformation was 28‰, which resulted in an increase of over 3000 times of coal permeability coefficient.3)In the paper, we obtained the relations between fractures evolution and gas migration & storage. We proposed the“cap distribution”of fractures and separations, and the concepts of two enrichment areas of pressure relief gas, namely the fractured zone and separation zone in bending zone. Systematically and organically combined with gas migration and storage, rock movement, fractures and separations evolution, we got the coupling law of mining fractures field and gas migration field. 4)In the paper, we got the gas migration law of distant protected layers under the extremely thick igneous rock. The pressure relief gas flowed directly or along vertical fractures to the separations, making the separations be enrichment areas of pressure relief gas and easy for gas drainage. The back calculation of drainage data in field test proved that the separations full of gas existing nearby the pressure relief coal seams.5)In the paper, we developed an special gas drainage method, namely the distant penetration boreholes, which successfully applied to the practice in the Haizi coal mine. The practice in the Haizi coal mine has shown that, the amount of gas drainage stayed at above 4m3/min in the regular period gas, drainage rate could reach 73% in the middle coal group by draining for a year, with a gas drainage radius over 100 m, and the outburst danger of protected layers were eliminated. The method was not used in other coal mines at home and abroad.更多还原