【作者】 刘林；

【导师】 程远平；

【作者基本信息】 中国矿业大学 ， 安全技术及工程， 2010， 博士

【摘要】 针对我国瓦斯动力灾害程度日趋严重,保护层开采作为首选和最有效的区域性防突措施越来越受到重视的现状。本文采用弹性力学、渗流力学、岩体力学等基础理论,通过理论分析、相似模拟、数值模拟和现场试验考察等研究途径,较为全面的研究了远距离下保护层开采后上覆煤岩体的应力分布、膨胀变形、被保护层的卸压保护范围、卸压瓦斯流动规律及煤层卸压瓦斯抽采方法,研究成果可为下保护层开采设计和上被保护层的卸压瓦斯抽采提供重要的参考。论文分析了近水平煤层工作面采场上覆煤岩体的受力状态(工作面倾向),得出了上被保护层的应力和下沉量的表达式。结合理论分析、数值模拟及现场考察结果,获得了倾向上被保护层工作面的应力分布及煤层膨胀变形规律。被保护层在保护层工作面机巷、风巷法向投影范围内均获得卸压效果。充分卸压边界(卸压角确定的边界)与煤柱边缘的法线投影之间区域(称为倾向扩界区域)煤体的应力降低和膨胀变形程度较工作面中部区域有所减少,但煤层透气性能明显改善,说明通过对其卸压瓦斯的抽采,扩界区域同样可处于保护范围内,近水平下保护层倾向卸压角可由锐角提高至90°,即被保护层工作面可与保护层工作面实现等宽布置。采用模型实验、数值模拟及现场考察等方法,获得了近水平上被保护层工作面走向上的应力变化及煤层膨胀变形规律。沿工作面走向,可分为原始应力区、集中应力区、卸压区和应力逐渐恢复区。保护层工作面采空区走向边界在被保护层上的法向投影范围内均获得卸压效果,在56°走向卸压角范围之内的被保护层,地应力下降及煤层膨胀变形较大,在充分卸压边界(卸压角确定的边界)与煤柱边缘的法线投影之间区域(称为走向扩界区域)的煤体的煤体地应力下降及煤层膨胀变形相对较小,但煤层透气性能同样明显改善,也说明通过对其卸压瓦斯的抽采,扩界区域同样可处于保护范围内,即走向卸压角可由56°提高至90°左右。结合远距离被保护层的裂隙发育特征,文章分析了远距离上被保护层的瓦斯流动及汇集特征,并获得了远距离上被保护层的卸压瓦斯抽采方法及相关技术参数,上被保护层卸压瓦斯抽采主要包括底板岩巷网格式上向穿层钻孔抽采和地面钻井抽采两种方式。通过对淮南潘三煤矿进行远距离下保护层开采现场试验,有效降低了上被保护层的瓦斯含量,彻底消除了突出煤层的危险性,实现了突出煤层的安全高效开采。根据考察结果,淮南潘三煤矿上被保护层C13煤层变形稳定后的相对膨胀变形为20.74‰,煤层透气性系数增大2592倍,煤层瓦斯抽采率达62%,煤层瓦斯压力由4.1MPa降为0.51MPa,瓦斯含量由10m3/t降为3.8m3/t。另外,根据现场试验考察验证,认为理论分析、相似材料模拟及数值模拟等方法得出的结论是可靠、合理的。更多还原

【Abstract】 Exploitation of protective seam as a principal and effective measure for avoiding gas and coal outburst has received increasingly attention due to the severe degree of gas dynamic disaster. The present study utilizes fundamental theories such as elastic mechanics, percolation mechanics, rock mechanics, and the like to research on stress distribution, expanding deformation, the pressure-relief and protective range of protected seam, the law of pressure-relief gas flowing and the method of pressure-relief gas exploiting of upper coal and strata after the long distance protective seam exploited, using the following means: theoretical analysis, similar simulation, numerical value simulation and so forth. The results can provide the crucial reference for exploitation of protective seam as well as pressure-relief gas extraction.This dissertation analyzes the state bearing the force of upper coal-rock mass, yields the expressions of stress and squate with respect to the upper protected seam. Based on theoretical analysis, similar simulation, numerical value simulation and observation on the spot, the study concludes the laws of stress distribution and expanding deformation regarding the oblique working face of upper protected seam. The pressure-relief effect is obtained in the range of normal projection as regards the protected seam projecting roadway and wind roadway of protected seam’s working face, stress in the central section of oblique working face with a dramatically decline and a little change in the two sides of coal pillar. Also, coal seam occurs in expanding deformation. In particular, the central section of working face deforms a lot and two sides relatively small. The relative pressure-relief guide line of coal mass between the completely pressure-relief boundary (i.e. certain boundary of pressure-relief angle) and the normal projection of pillar edge(called oblique extending area) satisfies the request of protective seam exploiting. The area The normal projection between pressure-relief boundary and edge of coal pillar. This demonstrates that the expanding area still lies in its protected range. The widths of working faces regarding protective seam and protected seam are the similar with each other, i.e. inclining pressure-relief the angle can occur in change from acute angle to right angle 90°.The paper presents the laws of stress change and expanding deformation with regard to the working face of upper protected seam, adopting simulation test, numerical value simulation and observation on the spot and so on. Along direction of working face, the area can be divided into four sections,namely original stress area, concentrated stress area, pressure-relief area and gradual resuming area. All the pressure-relief effect is obtained in the range of normal projection which the gob along working face of protective seam projects protected seam. In the protected seam with the range of 56°direction of pressure-relief angle, terrestrial stress falls and expanding deformation occurs to a great extent in coal. The terrestrial stress of coal mass, which is between the completely pressure-relief boundary (i.e. certain boundary of pressure-relief angle) and the normal projection of pillar edge(called oblique extending area), declines and coal seam occurs in expanding deformation The expanding deformation satisfies the technique guide line, that is, pressure-relief angle can give rise to about 90°from 56°.As for long distance protected seam, this study, associating with fracture development characteristics of long distance upper protected seam, surveys the characteristics of gas flowing and influx, and found the methods of pressure-relief gas extraction and relative parameters. Pressure-relief gas extraction of upper protected seam mainly involves two ways: extraction from the net-like floor roadway to penetrating borehole and drilling extraction on the floor. The current study carries out an application test on exploitation of long distance lower protective seam in PanSan Coal Mine, HuaiNan, reduces the gas content of upper protected seam, eradicates the disaster of outburst coal seams and realizes their exploitation safely and effectively. According to the results of examination, relative expanding deformation is 20.74‰, permeability coefficient is 2592 times, the rate of gas extraction reaches 62%, gas pressure falls from 4.1MPa to0.51MPa and gas content from 10m3/t to 3.8m3/t after the deformation stabilization of upper protected seam C13 in PanSan Coal Mine, HuaiNan. In addition, results have a reliability and rationality applying the ways of the theoretical analysis, similar simulation numerical value simulation, etc.更多还原