顺煤层剪切带煤与瓦斯突出机理分析
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摘要
为了确定顺煤层剪切带的煤与瓦斯突出机理,在对顺煤层剪切带的受力状态进行分析的基础上,应用Mohr-Coulomb理论研究了顺煤层剪切带的形成机制,并探讨了顺煤层剪切带内的煤层变化特征、瓦斯含量和瓦斯压力特征及地应力对煤与瓦斯突出的影响。结果表明:当煤层倾角接近剪切滑动的临界角时,易产生薄煤区,而远离临界角时,煤层厚度增加,煤层厚度剧烈变化部位为应力集中区并具有较高的应力梯度;顺煤层剪切带内的压应力、煤层的面理化结构和煤层厚度的剧烈变化使其在宏观上形成了高瓦斯含量和高瓦斯压力特征,微观上糜棱煤细颈瓶型的孔隙形态为发生煤与瓦斯突出提供了必要的介质条件;在紧闭褶皱区,煤与瓦斯突出类型以突出为主,在宽缓褶皱区和伸展型顺煤层剪切带内,煤与瓦斯突出类型以压出和倾出为主。顺煤层剪切带内的高地应力、高瓦斯压力和发育的构造煤等3个因素是煤与瓦斯突出发生的主要原因。
In order to determine the mechanism of coal and gas outbursts in the shear zone of coal seam, the formation mechanism of the shear zone was analyzed by Mohr-Coulomb theory based on the analysis of the stress state in the shear zone seam, and the variation characteristics of coal seam, gas content and gas pressure characteristics and the effect of ground stress on outbursts were also analyzed. The results showed that it was easy to cause thin coal zones when the coal seam dip was close to the critical angle of shearing slip. While, when the dip was far from the critical angle, the thickness of coal seam increased and the dramatic change region of coal seam is the stress concentration zone with high stress gradient; the compressive stress, the surface physicochemical structure and the drastic changes in thickness of coal seam made the characteristics of high gas content and pressure in macro perspectives, in micro perspectives the pore morphology of mylonitized coal with flask shape provides necessary medium conditions for the occurrence of coal and gas outburst. It was mainly with outbursts in compactly folded region, while in loosely folded zone it was mainly with extrusion and poured out. The main reasons of coal and gas outburst in the shear zone of coal seam are high ground stress, high gas pressure and developed tectonic coal.
In order to determine the mechanism of coal and gas outbursts in the shear zone of coal seam, the formation mechanism of the shear zone was analyzed by Mohr-Coulomb theory based on the analysis of the stress state in the shear zone seam, and the variation characteristics of coal seam, gas content and gas pressure characteristics and the effect of ground stress on outbursts were also analyzed. The results showed that it was easy to cause thin coal zones when the coal seam dip was close to the critical angle of shearing slip. While, when the dip was far from the critical angle, the thickness of coal seam increased and the dramatic change region of coal seam is the stress concentration zone with high stress gradient; the compressive stress, the surface physicochemical structure and the drastic changes in thickness of coal seam made the characteristics of high gas content and pressure in macro perspectives, in micro perspectives the pore morphology of mylonitized coal with flask shape provides necessary medium conditions for the occurrence of coal and gas outburst. It was mainly with outbursts in compactly folded region, while in loosely folded zone it was mainly with extrusion and poured out. The main reasons of coal and gas outburst in the shear zone of coal seam are high ground stress, high gas pressure and developed tectonic coal.
引文
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[14]曹运兴,彭立世,侯泉林.顺煤层断层的基本特征及其地质意义[J].地质评论,1993,39(6):522–528.
[15]张子敏,张玉贵.大平煤矿特大型煤与瓦斯突出瓦斯地质分析[J].煤炭学报,2005,30(2):137–140.
[2]HARGRAVES A J.Instantaneous outburst of coal and gas:a review[J].Proceedings of Australasian of the Institution of Mining and Metallurgy,1983,285:l–37.
[3]焦作矿业学院瓦斯地质课题组.瓦斯地质概论[M].北京:煤炭工业出版社,1990.
[4]于不凡.煤和瓦斯突出机理[M].北京:煤炭工业出版社,1985.
[5]宁超,黄波.煤层中顺层剪切带的力学分析及形成[M]//张子戌,张子敏,王兆丰.瓦斯地质与瓦斯防治进展.北京:煤炭工业出版社,2007.
[6]蔡成功,王佑安.煤与瓦斯突出一般规律定性定量分析研究[J].中国安全科学学报,2004,14(6):109–112.
[7]秦勇,叶建平,林大扬,等.煤储层厚度与其渗透性及含气性关系初步探讨[J].煤田地质与勘探,2000,28(1):24–27.
[8]严继民,张培元.吸附与凝聚[M].北京:科学出版社,1979.
[9]琚宜文,姜波,王桂梁,等.构造煤结构及储层物性[M].徐州:中国矿业大学出版社,2005:82–115.
[10]肖贤明,任德贻.滑动构造引起动力变质作用的发现及初步研究[J].煤田地质与勘探,1987,15(4):29–34.
[11]ZHU Wenlu,WONG Tengfong.The transition from brittle faulting to cataclastic flow:Permeability evolution[J].Journal of Geophysical Research(Solid Earth),1997,102(B2):3027–3041.
[12]ANTONELLINI M,AYDIN A.Effect of faulting on fluid flow in porous sandstones:Petrophysical properties[J].AAPG Bulletin,1994,78(3):355–377.
[13]曹运兴,彭立世.顺煤断层的基本类型及其对瓦斯突出带的控制作用[J].煤炭学报,1995,20(4):413–418.
[14]曹运兴,彭立世,侯泉林.顺煤层断层的基本特征及其地质意义[J].地质评论,1993,39(6):522–528.
[15]张子敏,张玉贵.大平煤矿特大型煤与瓦斯突出瓦斯地质分析[J].煤炭学报,2005,30(2):137–140.