侧限压缩下破碎矸石混合粒径非Darcy流渗透特性
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摘要
房柱式及巷式矸石充填开采中,煤柱与矸石两两相隔,破碎矸石充填体处于侧限压缩状态,破碎矸石的密实程度、孔隙特征及渗透特性对于煤层瓦斯流动及地下水渗流的控制具有重要的价值。基于稳态渗透法及轴向位移控制法,利用一套自制的破碎岩体渗透试验系统,测定了破碎矸石在不同混合粒径下承压过程中的非Darcy流渗透特性,得到渗透特性(渗透率k和非Darcy流β因子)随孔隙率的变化规律。研究表明:1)雷诺数计算及孔压梯度与渗流速度关系曲线说明破碎矸石的渗透特征属于非Darcy流;2)孔隙率随着压缩位移的增加而减小,对于混合粒径试样,较小颗粒充填到较大颗粒的孔隙中,是使岩样的初始孔隙率减小的主要原因;3)在侧限压缩下,大颗粒受挤压破碎是产生0~2.5 mm粒径的原因,而渗流造成细小颗粒质量流失;4)侧限压缩下,渗透率总的趋势减小,而非Darcy流β因子增加,但在压缩过程中,渗透特性的变化趋势受颗粒粒径的影响会出现局部波折,说明破碎矸石的渗透特性与侧限压缩位移、颗粒粒径大小、压缩破碎、排列方式及孔隙结构(通道)有关。
In room-pillar and roadway gangue backfill mining, the coal pillar and gangue are interval, and crushed gangue are under confined compression, besides which, the compaction, porosity and seepage properties of crushed gangue play a significant role in the control of coal seam gas and groundwater flow. Based on the steady-state flow measurement and axial displacement control method, a self–designed testing system for water flow in crushed rocks has been used to monitor the non-Darcy seepage properties of mixture particles of crushed gangue under confined water pressure, and the experiment has obtained the relation between seepage properties(permeability k and non-Darcy coefficient β) and porosity. Testing results have indicated that: 1) The Re calculation and the pore pressure gradient and flow velocity curves have shown that the water seepage flow in crushed gangue is a non-Darcy flow. 2) The porosity of crushed gangue is strongly influenced by compaction(axial displacement) and particle mixture. The porosity decreases with the increase of axial displacement and decrease of bigger particle size, respectively. 3) During the compaction, some larger particles being crushed and broken is the main reason that gave birth to particle size of 0-2.5 mm, and small particles have been washed away because of the effect of water seepage. 4) In general, under confined compression, the permeability k decreases while the non-Darcy coefficient β increases. The fluctuation of seepage properties curves has shown that the seepage properties of crushed gangue are not only related to compaction levels, mixture sizes, particle crushing, style of arrangement, but also to the pore channel.
In room-pillar and roadway gangue backfill mining, the coal pillar and gangue are interval, and crushed gangue are under confined compression, besides which, the compaction, porosity and seepage properties of crushed gangue play a significant role in the control of coal seam gas and groundwater flow. Based on the steady-state flow measurement and axial displacement control method, a self–designed testing system for water flow in crushed rocks has been used to monitor the non-Darcy seepage properties of mixture particles of crushed gangue under confined water pressure, and the experiment has obtained the relation between seepage properties(permeability k and non-Darcy coefficient β) and porosity. Testing results have indicated that: 1) The Re calculation and the pore pressure gradient and flow velocity curves have shown that the water seepage flow in crushed gangue is a non-Darcy flow. 2) The porosity of crushed gangue is strongly influenced by compaction(axial displacement) and particle mixture. The porosity decreases with the increase of axial displacement and decrease of bigger particle size, respectively. 3) During the compaction, some larger particles being crushed and broken is the main reason that gave birth to particle size of 0-2.5 mm, and small particles have been washed away because of the effect of water seepage. 4) In general, under confined compression, the permeability k decreases while the non-Darcy coefficient β increases. The fluctuation of seepage properties curves has shown that the seepage properties of crushed gangue are not only related to compaction levels, mixture sizes, particle crushing, style of arrangement, but also to the pore channel.
引文
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[21]SONG X Y,GONG C C,LI D X.Study on structural characteristic and mechanical property of coal gangue in the activation process[J].Journal of the American Ceramic Society,2004,32(3):358-363.
[22]孙希奎.置换条带开采中充填体强度分析[J].煤炭科学技术,2011,39(5):33-36.SUN Xikui.Analysis on backfill material strength of replacement for belt coal pillar mining[J].Coal Science and Technology,2011,39(5):33-36.
[23]姜振泉,赵道辉,隋旺华,等.煤矸石固结压密性与颗粒级配缺陷关系研究[J].中国矿业大学学报,1999,28(3):212-216.JIANG Zhenquan,ZHAO Daohui,SUI Wanghua,et al.Study on relationship between consolidation-compactness and size grade shortage of coal gangue[J].Journal of China University of Mining&Technology,1999,28(3):212-216.
[24]孔祥言.高等渗流力学[M].2版.合肥:中国科学技术大学出版社,2010:33-34.
[2]MCKINNON E.The environmental effects of mining waste disposal at Lihir Gold Mine,Papua New Guinea[J].Journal of Rural Remote Environmental Health,2002(1):40-50.
[3]缪协兴.综合机械化固体充填采煤技术研究进展[J].煤炭学报,2012,37(8):1247-1255.MIAO Xiexing.Progress of fully mechanized mining with solid backfilling technology[J].Journal of China Coal Society,2012,37(8):1247-1255.
[4]缪协兴,钱鸣高.中国煤炭资源绿色开采研究现状与展望[J].采矿与安全工程学报,2009,26(1):1-14.MIAO Xiexing,QIAN Minggao.Research on green mining of coal resources in China current status and future prospects[J].Journal of Mining&Safety Engineering,2009,26(1):1-14.
[5]缪协兴,张吉雄,郭广礼.综合机械化固体充填采煤方法与技术研究[J].煤炭学报,2010,35(1):1-6.MIAO Xiexing,ZHANG Jixiong,GUO Guangli.Study on waste-filling method and technology in fully-mechanized coal mining[J].Journal of China Coal Society,2010,35(1):1-6.
[6]缪协兴,黄艳利,巨峰.密实充填采煤的岩层移动理论研究[J].中国矿业大学学报,2012,41(6):863-867.MIAO Xiexing,HUANG Yanli,JU Feng.Strata movement theory of dense backfill mining[J].Journal of China University of Mining&Technology,2012,41(6):863-867.
[7]LOMIZE G M.Flow in fractured rocks[M].Moscow:Gosemergoizdat,1951.
[8]KOGURE K.Experimental study on permeability of crushed rock[J].Memoirs of the Defense Academy,Japan,1976,16(4):149-154.
[9]ZOBACK M D,BYERLEE J D.Note on the deformational behavior and permeability of crushed granite[J].International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1976,13(10):291-294.
[10]MCCORQUODALE J A,HANNOURA A-A A,NASSER M S.Hydraulic conductivity of rockfill[J].Journal of Hydraulic Research,1978,16(2):123-137.
[11]MIAO X X,LI S C,CHEN Z Q.Experimental study of seepage properties of broken sandstone under different porosities[J].Transport in Porous Media,2011,86(3):805-814.
[12]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 the properties of time-dependent deformation-seepage in water-saturated broken sandstone[J].Journal of Mining&Safety Engineering,2011,28(4):542-547.
[13]MA D,MIAO X X,JIANG G H,et al.An experimental investigation of permeability measurement of water flow in crushed rocks[J].Transport in Porous Media,2014,105(3):571-595.
[14]MA D,BAI H B,CHAN Z Q,et al.Effect of particle mixture on seepage properties of crushed mudstones[J].Transport in Porous Media,2015,108(2):257-277.
[15]MA D,BAI H B,MIAO X X,et al.Compaction and seepage properties of crushed limestone particle mixture:an experimental investigation for Ordovician Karst collapse pillar groundwater inrush[J].Environmental Earth Sciences,2016,75(1):11.
[16]BIAN Z F,DONG J.The impact of disposal and treatment of coal mining wastes on environment and farmland[J].Environmental Geology,2009,58(3):625-634.
[17]刘松玉,童立元,邱钰,等.煤矸石颗粒破碎及其对工程力学特性影响研究[J].岩土工程学报,2005,27(5):505-510.LIU Songyu,TONG Liyuan,QIU Yu,et al.Crushable effects on engineering mechanical properties of colliery waste[J].Chinese Journal of Geotechnical Engineering,2005,27(5):505-510.
[18]许家林,尤琪,朱卫兵,等.条带充填控制开采沉陷的理论研究[J].煤炭学报,2007,32(2):119-122.XU Jialin,YOU Qi,ZHU Weibing,et al.Theoretical study of strip-filling to control mining subsidence[J].Journal of China Coal Society,2007,32(2):119-122.
[19]刘松玉,邱钰,童立元,等.煤矸石的动力特性试验研究[J].东南大学学报(自然科学版),2005,35(2):280-283.LIU Songyu,QIU Yu,TONG Liyuan,et al.Experimental research on dynamic properties of coal mining wastes[J].Journal of Southeast University(Natural Science Edition),2005,35(2):280-283.
[20]徐俊明,张吉雄,黄艳利,等.充填综采矸石粉煤灰压实变形特性试验研究及应用[J].采矿与安全工程学报,2011,28(1):158-162.XU Junming,ZHANG Jixiong,HUANG Yanli,et al.Experimental research on the compress deformation characteristic of waste-fly ash and its application in backfilling fully mechanized coal mining technology[J].Journal of Mining&Safety Engineering,2011,28(1):158-162.
[21]SONG X Y,GONG C C,LI D X.Study on structural characteristic and mechanical property of coal gangue in the activation process[J].Journal of the American Ceramic Society,2004,32(3):358-363.
[22]孙希奎.置换条带开采中充填体强度分析[J].煤炭科学技术,2011,39(5):33-36.SUN Xikui.Analysis on backfill material strength of replacement for belt coal pillar mining[J].Coal Science and Technology,2011,39(5):33-36.
[23]姜振泉,赵道辉,隋旺华,等.煤矸石固结压密性与颗粒级配缺陷关系研究[J].中国矿业大学学报,1999,28(3):212-216.JIANG Zhenquan,ZHAO Daohui,SUI Wanghua,et al.Study on relationship between consolidation-compactness and size grade shortage of coal gangue[J].Journal of China University of Mining&Technology,1999,28(3):212-216.
[24]孔祥言.高等渗流力学[M].2版.合肥:中国科学技术大学出版社,2010:33-34.