三轴应力作用下破碎煤体渗透特性演化规律
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摘要
深部破碎煤岩体受地应力和开采扰动常处于三向应力状态,其渗透特性是影响矿井突水灾害预防和瓦斯抽放的重要因素之一。为研究深部破碎煤体的渗透性能,采用自主研发的破碎岩石三轴渗流试验系统,并设计一套破碎煤体三轴渗流试验方案,进行三轴应力作用下破碎煤体渗流试验,得到破碎煤体渗透特性随围压及孔隙率的演化规律。试验结果表明:①三轴应力作用下破碎煤样渗流雷诺数最大值为47. 58,渗流速度与孔压梯度两者之间符合Forchheimer关系;②三轴应力作用下破碎煤样的孔隙率与围压的变化规律呈负相关,各级轴向位移下,两者服从对数函数关系;③随着有效应力的增大,各粒径下的破碎煤样孔隙率逐渐减小,破碎煤样孔隙率的理论计算值与试验结果较为吻合,表明文中给出的孔隙率计算方法可行;④各级轴向位移下,破碎煤样的渗透率随围压增大而减小,不同粒径的破碎煤样渗透率随围压的演化规律可用k=me~(nσ3)公式表示,颗粒粒径越大,破碎煤样的渗透率随围压的变化越敏感;⑤颗粒粒径及孔隙排列方式影响破碎煤样渗透性能,不同粒径破碎煤样随孔隙率的减小,渗透率整体减小,非Darcy流β因子呈增大趋势,其中渗透率的量级为10~(-14)～10~(-10) m~2,非Darcy流β因子的量级为10~7～10~(11)m~(-1)。所得研究结论有助于增强深部破碎煤岩体渗透特性演化规律的认识。
The deep broken coal and rock mass are often in the state of triaxial stress,due to the crustal stress and mining disturbance, and its permeability is one of the important factors that affect the prevention of mine water inrush disaster and gas drainage. This research aims to carry out the seepage test of broken coal under the triaxial stress,using the self-developed triaxial permeability test system for broken rocks,and the evolution law of the permeability characteristics of the broken coal with the confining pressure and the porosity are obtained. The results are as follows ①the maximum Reynolds number in fluid flow through broken coal under triaxial stress is 47. 58,and the seepage velocity and pore pressure gradient are fitted by the Forchheimer relationship. ② Under triaxial stress,there is a negative correlation between the porosity and confining pressure of broken coal, and both agree with the logarithmic function relationship. ③ The theory of broken coal porosity values are close to the experimental results,and the porosity decreases with the increase of the effective stress. Thus it shows that the calculation method of porosity is feasible. ④ Under the axial displacement at all levels, the permeability of broken coal decreases with the increase of confining pressure, and the evolution law of permeability of broken coal with different diameter sizes with confining pressure can be expressed by formula k = me~(nσ3). The larger the particle size,the more sensitive the permeability of the broken coal changes with the confining pressure. ⑤ The permeability of broken coal is affected by particle size and pore arrangement. With the decrease of porosity, the permeability of the broken coal in different diameter sizes are on the downward trend, and nonDarcy flow β factor increases,integrally. The order of the permeability is 10~(-14)-10~(-10)m~2;the order of non-Darcy flow βfactor is 10~7-10~(11)m~(-1). The results will be helpful to the understanding of permeability evolution of broken coal and rock mass.
The deep broken coal and rock mass are often in the state of triaxial stress,due to the crustal stress and mining disturbance, and its permeability is one of the important factors that affect the prevention of mine water inrush disaster and gas drainage. This research aims to carry out the seepage test of broken coal under the triaxial stress,using the self-developed triaxial permeability test system for broken rocks,and the evolution law of the permeability characteristics of the broken coal with the confining pressure and the porosity are obtained. The results are as follows ①the maximum Reynolds number in fluid flow through broken coal under triaxial stress is 47. 58,and the seepage velocity and pore pressure gradient are fitted by the Forchheimer relationship. ② Under triaxial stress,there is a negative correlation between the porosity and confining pressure of broken coal, and both agree with the logarithmic function relationship. ③ The theory of broken coal porosity values are close to the experimental results,and the porosity decreases with the increase of the effective stress. Thus it shows that the calculation method of porosity is feasible. ④ Under the axial displacement at all levels, the permeability of broken coal decreases with the increase of confining pressure, and the evolution law of permeability of broken coal with different diameter sizes with confining pressure can be expressed by formula k = me~(nσ3). The larger the particle size,the more sensitive the permeability of the broken coal changes with the confining pressure. ⑤ The permeability of broken coal is affected by particle size and pore arrangement. With the decrease of porosity, the permeability of the broken coal in different diameter sizes are on the downward trend, and nonDarcy flow β factor increases,integrally. The order of the permeability is 10~(-14)-10~(-10)m~2;the order of non-Darcy flow βfactor is 10~7-10~(11)m~(-1). The results will be helpful to the understanding of permeability evolution of broken coal and rock mass.
引文
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[5] ZHENG Jiangtao, JU Yang, ZHAO Xi. Influence of pore structures on the mechanical behavior of low-permeability sandstones:Numerical reconstruction and analysis[J]. International Journal of Coal Science&Technology,2014,1(3);329-337.
[6] PANG Yihui,WANG Guofa,DING Ziwei. Mechanical model of water inrush from coal seam floor based on triaxial seepage experiments[J]. International Journal of Coal Science&Technology 2014,1(4):428-433.
[7]陈占清,李顺才,浦海,等.采动岩体蠕变与渗流耦合动力学[M].北京:科学出版社,2010:70-139.
[8]李顺才,陈占清,缪协兴,等.饱和破碎砂岩随时间变形-渗流特性试验研究[J].采矿与安全工程学报,2011,28(4):542-547.LI Shuncai, CHEN Zhanqing, MIAO Xiexing, et al. Experimental study on saturated and fractured sandstone deformation-seepage characteristics with time[J]. Journal of Mining&Safety Engineering,2011,28(4):542-547.
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[11]马占国,缪协兴,李兴华,等.破碎页岩渗透特性[J].采矿与安全工程学报,2007,24(3):260-264.MA Zhanguo, MIAO Xiexing, LI Xinghua, et al. Permeability of broken shale[J]. Journal of Mining&Safety Engineering, 2007,24(3):260-264.
[12]王路珍,陈占清,孔海陵,等.加载历程对配径碎煤渗透特性影响的试验研究[J].岩土力学,2013,34(5):1325-1330.WANG Luzhen,CHEN Zhanqing,KONG Hailing,et al. Experimental study of impact of loading history on permeability characteristics of broken coal with different grain size gradations[J]. Rock and Soil Mechanics,2013,34(5):1325-1330.
[13] WANG L Z,CHEN Z Q,SHEN H D. Experimental study on the type change of liquid flow in broken coal samples[J]. Journal of Coal Science and Engineering(China),2013,19(1):19-25.
[14]王路珍.变质量破碎泥岩渗透性的加速试验研究[D].徐州:中国矿业大学,2014.WANG Luzhen. Accelerated experimental study on permeability for broken mudstone with mass loss[D]. Xuzhou:China University of Mining and Technology,2014.
[15]姚邦华.破碎岩体变质量流固耦合动力学理论及应用研究[D].徐州:中国矿业大学,2012.YAO Banghua. Research on variable msss fluid-solid coupling dynamic theory of broken rockmass and application[D]. Xuzhou:Chi-na University of Mining and Technology,2012.
[16]姚邦华,茅献彪,魏建平,等.考虑颗粒迁移的陷落柱流固耦合动力学模型研究[J].中国矿业大学学报,2014,43(1):30-35.YAO Banghua,MAO Xianbiao,WEI Jianping,et al. Study on coupled fluid-solid model for collapse columns considering the effect of particle transport[J]. Journal of China University of Mining&Technology,2014,43(1):30-35.
[17]张天军,尚宏波,李树刚,等.分级加载下破碎砂岩渗透特性试验及其稳定性分析[J].煤炭学报,2016,41(5):1129-1136.ZHANG Tianjun,SHANG Hongbo,LI Shugang,et al. Experimental study on permeability characteristics of broken sandstone and its stability analysis under step loading[J]. Journal of China Coal Society,2016,41(5):1129-1136.
[18]张天军,尚宏波,李树刚,等.破碎矸石分级加载蠕变过程中的渗流试验研究[J].采矿与安全工程学报,2018,35(1):188-196.ZHANG Tianjun, SHANG Hongbo,LI Shugang,et al. An seepage experimental study on broken gangue under step loading during creep process[J]. Journal of Mining&Safety Engineering,2018,35(1):188-196.
[19]尹光志,刘玉冰,李铭辉,等.真三轴加卸载应力路径对原煤力学特性及渗透率影响[J].煤炭学报,2018,43(1):131-136.YIN Guangzhi,LIU Yubing,LI Minghui,et al. Influence of true triaxial loading-unloading stress paths on mechanical property and permeability of coal[J]. Journal of China Coal Society, 2018,43(1):131-136.
[20]康向涛,黄滚,宋真龙,等.三轴压缩下含瓦斯煤的能耗与渗流特性研究[J].岩土力学,2015,36(3):762-768.KANG Xiangtao, HUANG Gun, SONG Zhenlong, et al. Research on characteristics of energy dissipation and seepage of coal containing gas under triaxial compression[J]. Rock and Soil Mechanics,2015,36(3):762-768.
[21]张冲,刘晓斐,王笑然,等.三轴加载煤体瓦斯渗流速度-温度联合响应特征[J].煤炭学报,2018,43(3):743-750.ZHANG Chong, LIU Xiaofei, WANG Xiaoran,et al. Combination response characteristics of gas seepage velocity-temperature under triaxial loading[J]. Journal of China Coal Society, 2018,43(3):743-750.
[22]张天军,尚宏波,李树刚,等.三轴应力下不同粒径破碎砂岩渗透特性试验研究[J].岩土力学,2018,39(7):1-10.ZHANG Tianjun,SHANG Hongbo,LI Shugang,et al. The permeability test of broken sandstone under the three-dimensional stress[J].Rock and Soil Mechanics,2018,39(7):1-10.
[23]孔祥言.高等渗流力学[M].合肥:中国科学技术大学出版社,2010.
[24]祝捷,姜耀东,孟磊,等.载荷作用下煤体变形与渗透性的相关性研究[J].煤炭学报,2012,37(6):984-988.ZHU Jie, JIANG Yaodong, MENG Lei, et al. Pertinence study on deformation and permeability of coal containing methane during loading process[J]. Journal of China Coal Society, 2012,37(6):984-988.
[2]马占国,缪协兴,陈占清,等.破碎煤体渗透特性的试验研究[J].岩土力学,2009,30(4):985-988,996.MA Zhanguo, MIAO Xiexing,CHEN Zhanqing,et al.Experimental study on permeability of broken coal[J].Rock and Soil Mechanics,2009,30(4):985-988,996.
[3] YANG S D. Water abundance of mine floor limestone by simulation experiment[J]. International Journal of Mining Science&Technolo-gy,2016,26(3):495-500.
[4] NASSER M S,MCCORQUODALE J A. Analysis of wave action in permeable structures[J]. Canadian Journal of Civil Engineering,2011,3(1):98-106.
[5] ZHENG Jiangtao, JU Yang, ZHAO Xi. Influence of pore structures on the mechanical behavior of low-permeability sandstones:Numerical reconstruction and analysis[J]. International Journal of Coal Science&Technology,2014,1(3);329-337.
[6] PANG Yihui,WANG Guofa,DING Ziwei. Mechanical model of water inrush from coal seam floor based on triaxial seepage experiments[J]. International Journal of Coal Science&Technology 2014,1(4):428-433.
[7]陈占清,李顺才,浦海,等.采动岩体蠕变与渗流耦合动力学[M].北京:科学出版社,2010:70-139.
[8]李顺才,陈占清,缪协兴,等.饱和破碎砂岩随时间变形-渗流特性试验研究[J].采矿与安全工程学报,2011,28(4):542-547.LI Shuncai, CHEN Zhanqing, MIAO Xiexing, et al. Experimental study on saturated and fractured sandstone deformation-seepage characteristics with time[J]. Journal of Mining&Safety Engineering,2011,28(4):542-547.
[9]李顺才,缪协兴,陈占清,等.承压破碎岩石非Darcy渗流的渗透特性试验研究[J].工程力学,2008,25(4):85-92.LI Shuncai, MIAO Xiexing, CHEN Zhanqing, et al. Experimental study on seepage properties of non-darcy flow in confined broken rocks[J]. Engineering Mechanics,2008,25(4):85-92.
[10] MA Z G,MIAO X X,ZHANG F. Experimental study into permeability of broken mudstone[J]. Journal of China University of Mining&Technology,2007,17(2):147-151.
[11]马占国,缪协兴,李兴华,等.破碎页岩渗透特性[J].采矿与安全工程学报,2007,24(3):260-264.MA Zhanguo, MIAO Xiexing, LI Xinghua, et al. Permeability of broken shale[J]. Journal of Mining&Safety Engineering, 2007,24(3):260-264.
[12]王路珍,陈占清,孔海陵,等.加载历程对配径碎煤渗透特性影响的试验研究[J].岩土力学,2013,34(5):1325-1330.WANG Luzhen,CHEN Zhanqing,KONG Hailing,et al. Experimental study of impact of loading history on permeability characteristics of broken coal with different grain size gradations[J]. Rock and Soil Mechanics,2013,34(5):1325-1330.
[13] WANG L Z,CHEN Z Q,SHEN H D. Experimental study on the type change of liquid flow in broken coal samples[J]. Journal of Coal Science and Engineering(China),2013,19(1):19-25.
[14]王路珍.变质量破碎泥岩渗透性的加速试验研究[D].徐州:中国矿业大学,2014.WANG Luzhen. Accelerated experimental study on permeability for broken mudstone with mass loss[D]. Xuzhou:China University of Mining and Technology,2014.
[15]姚邦华.破碎岩体变质量流固耦合动力学理论及应用研究[D].徐州:中国矿业大学,2012.YAO Banghua. Research on variable msss fluid-solid coupling dynamic theory of broken rockmass and application[D]. Xuzhou:Chi-na University of Mining and Technology,2012.
[16]姚邦华,茅献彪,魏建平,等.考虑颗粒迁移的陷落柱流固耦合动力学模型研究[J].中国矿业大学学报,2014,43(1):30-35.YAO Banghua,MAO Xianbiao,WEI Jianping,et al. Study on coupled fluid-solid model for collapse columns considering the effect of particle transport[J]. Journal of China University of Mining&Technology,2014,43(1):30-35.
[17]张天军,尚宏波,李树刚,等.分级加载下破碎砂岩渗透特性试验及其稳定性分析[J].煤炭学报,2016,41(5):1129-1136.ZHANG Tianjun,SHANG Hongbo,LI Shugang,et al. Experimental study on permeability characteristics of broken sandstone and its stability analysis under step loading[J]. Journal of China Coal Society,2016,41(5):1129-1136.
[18]张天军,尚宏波,李树刚,等.破碎矸石分级加载蠕变过程中的渗流试验研究[J].采矿与安全工程学报,2018,35(1):188-196.ZHANG Tianjun, SHANG Hongbo,LI Shugang,et al. An seepage experimental study on broken gangue under step loading during creep process[J]. Journal of Mining&Safety Engineering,2018,35(1):188-196.
[19]尹光志,刘玉冰,李铭辉,等.真三轴加卸载应力路径对原煤力学特性及渗透率影响[J].煤炭学报,2018,43(1):131-136.YIN Guangzhi,LIU Yubing,LI Minghui,et al. Influence of true triaxial loading-unloading stress paths on mechanical property and permeability of coal[J]. Journal of China Coal Society, 2018,43(1):131-136.
[20]康向涛,黄滚,宋真龙,等.三轴压缩下含瓦斯煤的能耗与渗流特性研究[J].岩土力学,2015,36(3):762-768.KANG Xiangtao, HUANG Gun, SONG Zhenlong, et al. Research on characteristics of energy dissipation and seepage of coal containing gas under triaxial compression[J]. Rock and Soil Mechanics,2015,36(3):762-768.
[21]张冲,刘晓斐,王笑然,等.三轴加载煤体瓦斯渗流速度-温度联合响应特征[J].煤炭学报,2018,43(3):743-750.ZHANG Chong, LIU Xiaofei, WANG Xiaoran,et al. Combination response characteristics of gas seepage velocity-temperature under triaxial loading[J]. Journal of China Coal Society, 2018,43(3):743-750.
[22]张天军,尚宏波,李树刚,等.三轴应力下不同粒径破碎砂岩渗透特性试验研究[J].岩土力学,2018,39(7):1-10.ZHANG Tianjun,SHANG Hongbo,LI Shugang,et al. The permeability test of broken sandstone under the three-dimensional stress[J].Rock and Soil Mechanics,2018,39(7):1-10.
[23]孔祥言.高等渗流力学[M].合肥:中国科学技术大学出版社,2010.
[24]祝捷,姜耀东,孟磊,等.载荷作用下煤体变形与渗透性的相关性研究[J].煤炭学报,2012,37(6):984-988.ZHU Jie, JIANG Yaodong, MENG Lei, et al. Pertinence study on deformation and permeability of coal containing methane during loading process[J]. Journal of China Coal Society, 2012,37(6):984-988.