【作者】 吴海进；

【导师】 林柏泉；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2009， 博士

【摘要】 煤炭是我国的基础能源,随着开采深度的增加,瓦斯已成为严重威胁煤矿安全生产的主要因素。由于我国大多数煤田均属于低透气性煤层,故作为瓦斯治理最主要技术措施的钻孔抽采,实际效果并不理想。因此,通过对高瓦斯低透气性煤层卸压增透,提高抽采钻孔的单孔有效影响范围,已成为实现煤矿可持续发展的关键环节。本文首先从不同硬度煤体孔隙裂隙微观结构的研究入手,采用分形学方法,对压汞实验所得的孔隙结构和电镜扫描所得的煤样表面裂隙结构进行分形维数的计算,并发现随着煤体硬度的增加,孔隙裂隙结构的复杂程度越来越低。其次,基于对复杂裂隙结构的简化,建立了煤体裂隙结构瓦斯流动的毛细管和壁面模型,并基于相关假设,以达西渗流和菲克扩散定律为基础,研究在简化模型中瓦斯的流动和运移规律。同时,还推导出瓦斯在两种模型中的运动方程,并进行了流速和流量的分析。第三,利用模型分析结果对钻孔周围煤体中瓦斯的流动规律进行研究,得到钻孔影响范围煤层达到整体消突的时间t,同时通过钻孔周围煤体中两种模型瓦斯流动规律的对比分析,发现两种简化模型流动规律的差异主要体现在与时间量、位移量无关的系数上。继而以单通道毛细管瓦斯流动模型为基础,对水力割缝卸压范围内煤体中瓦斯的流动规律进行了理论研究,得到水力割缝卸压范围内达到整体消突的时间t,用以指导工程实践。第四,在建立“煤层钻割一体化卸压增渗实验系统”的基础上,以熔化石蜡板代替缝槽,对高压磨料射流割缝技术的应用效果进行了物理模拟。并通过应力传感器配合数据采集系统的数据分析发现:随着缝槽宽度的增加,卸压范围逐渐加大;当割缝高度一定时,垂直方向上,随着与缝槽距离的增加,卸压程度总体呈现逐渐减小的趋势,但受影响的范围却有一定程度的增加;但随着割缝高度的增加,上部煤层受影响的范围和强度均会不同程度的增加,尽管效果并不显著;另外,综合两侧的实验分析,还勾勒出了缝槽卸压的轮廓线。笔者还通过自制的透气性测试球对不同缝槽形成后的透气性变化规律进行了分析,确定了对应的有效卸压影响范围。并通过对位移测定装置测得的实验终态缝槽上方不同位置位移量数据的拟合,推导出了反应9mm缝槽形成后,下向位移量与距离关系的经验方程。同时,本文还通过建立数值计算模型,采用快速拉格朗日差分分析FLAC模拟软件,较为全面地对割缝缝槽的卸压效果进行了研究。首先,从理论上分析了钻孔与割缝的卸压效果,在相同的地应力和煤体力学参数下,钻孔的卸压效果远远落后于缝槽。通过二维模拟对缝槽的卸压影响因素进行了研究,包括缝槽的宽度、高度、垂直于缝槽平面的应力、最大主应力与缝槽平面法线方向的夹角以及缝槽之间的相互影响等。为更直观地研究割缝缝槽对于煤体的卸压状况,还通过FLAC3D模拟了单个缝槽和多个缝槽的卸压效果。另外,本文还基于芦岭煤矿的煤层赋存条件进行了顺层钻割孔、单排穿层钻割孔以及多排穿层钻割孔的的三维数值模拟分析,研究结果表明:穿层钻割和顺层钻割都能起到较为理想的卸压增透效果,尤其是在穿层多排钻孔的模拟中,由于相互的影响,形成了整体卸压,从而大幅度提高了区域煤层的整体透气性,为大面积区域性瓦斯预抽奠定了良好的基础。最后,为配合煤层割缝卸压技术的应用,解决工程实践中遇到的问题,研制了将机械钻进与磨料射流割缝相结合的高压磨料射流钻割一体化装备,并在此基础上将该装备应用于淮北矿业集团芦岭煤矿II8210工作面的底板岩巷穿层卸压增透和重庆天弘矿业有限公司盐井一矿主井K4-K2煤层石门揭煤的卸压增透工作中,对相关参数进行了测定分析。通过以上研究,在理论上推导出了割缝卸压范围内达到整体消突时间t的表达式,技术上开发了用于高瓦斯低透气性煤层卸压增透的“钻”“割”“抽”三位一体的技术措施,装备上研制了将机械钻进和割缝相结合的高压磨料射流钻割一体化装备,通过实际应用,穿层钻孔瓦斯日抽采纯量可增加11倍。更多还原

【Abstract】 Coal is the basic energy in our country, and gas has been to the main factor which serious threatens the safety in production as the increase of mining depth. in our country, most of the coalfield hold low permeability coal seam, so the actual effect isn’t perfect if take drainage borehole as the main technology. Therefore, enlarging the influence extent of one single drilling by pressure relief and permeability enhancements has been to the key segment for the sustainable development of the mine.Beginning as the research of the pores and fissures’microcosmic structure in the coal with different hardness, the thesis compares the fractal dimensions of the pore structure to the fissure structure and finds that both change to be less and less complex as the development of the coal’s hardness.Then, the author sets up two simplified models to describe the situation of the gas flowing in the fissures: the capillary and the wall laminar flowing model. Then derive the motion equations and the analysis of the flow velocities and the flow rates in the two models based upon the interrelated conjecture and Darcy law and Fick’s diffusion law.Thirdly, the thesis analyzes the gas flowing discipline in the coal around the drilling and obtains the overall gas rush perishing time. Moreover, the author finds that the main differences between the two models is the coefficients which is outlying with the time and the displacement, so just choose the capillary model when analyzing the effect of hydraulic slotting, obtains the overall gas rush perishing time as well in order to guide engineering practice.Fourthly, set up the experiment system and simulate the application effect of the technology of the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention by replacing slot with melting paraffin board. from the data analysis, the author finds that the pressure relief range change larger as the increase of the slotting width while in the vertical direction, the extent of the pressure relief change smaller as the increase of the distance with the slot. in addition, the influencing range and extent is increasing in the upward coal seam, draw the pressure relief outline from the experiment results of two sides. Moreover, analyze the discipline of the ventilation property by the self-regulated testing ball, obtain the valid pressure relief range. Obtain the empirical equation that describes the relationship between the lower displacement and the distance after the 9mm slot formed as well. Meanwhile, the author sets up numerical calculation model, research the pressure relief effect of hydraulic slotting by FLAC. Firstly, analyze the pressure relief effect of drilling and slotting and find that the pressure relief effect of drilling is behind slotting obviously at the same stress conditions and mechanics parameters. The thesis studies the influencing factors of the pressure relief by two dimension simulation. Simulate the pressure relief effect of one single slot and multi-slots by FLAC 3D as well. in addition, the thesis simulates the effects of the bed-parallel drilling and single row transverse drilling and multi-row transverse drilling and finds that the two drilling styles are both successful. Especially, the latter can increase the overall permeability which is a nice foundation for per-vacuuming gas in large areas.Finally, develop the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention equipment. The author popularizes the technology to the II8210 working face in Lu ling and the K4-K2 coal seam of the main coal of the No.1 coal in Yan Jing , evaluates and analyzes the interrelated parameters as well.From the research above, obtain the the overall gas rush perishing time in the pressure relief range by hydraulic slotting, while develop the drilling-slotting-pumping trinitarian technology which can be used to relieve pressure and enhance permeability of the coal with high concentration of gas and low permeability. Meanwhile, develop the High-Pressure Jet of Abrasive Drilling Slotting integration Outburst Prevention equipment, the everyday pumping net measure can increase 11 times by transverse drilling.更多还原