不同围压下破碎花岗岩非线性渗流特性试验研究
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摘要
随着我国高坝枢纽工程和高水头抽水蓄能电站的大规模兴建,高坝岩基和高压引水系统围岩将承受极高的渗透水压和水力坡降,不仅导致岩体渗流产生强烈的非线性,而且导致岩体发生渗漏、突透水和渗透破坏的风险急剧增大。采用Triaxial Cell三轴试验系统,开展不同围压(1~30 MPa)下阳江破碎花岗岩的非线性渗流试验,研究高水力梯度条件下破碎花岗岩的非线性渗流特性及其表征方法。试验结果表明,随着水力梯度的逐步增大,破碎花岗岩中的水力梯度与渗流流量呈非线性特征;在围压加载过程中破碎花岗岩的非线性渗流特征逐渐减弱。结合花岗岩的破碎形态和渗透率量级,提出了破碎花岗岩非线性渗流3种可能的成因机制即惯性效应、渗透失稳和固液界面效应。在该基础上分别采用二次函数型Forchheimer公式和幂函数型Izbash公式对试验结果进行拟合,结果表明二者均能很好地表征破碎花岗岩的非线性渗流行为。Forchheimer公式非线性系数既能够表征渗流的惯性效应,又能表征渗透失稳机制,其在量值上随着围压的增大呈现正负交替现象,与围压加载过程中破碎花岗岩裂纹的闭合和扩展密切相关;Izbash公式非线性系数则既能够表征渗流的惯性效应,又能表征低渗介质非线性渗流的固液界面效应,其在量值上与围压存在相关性很好的幂函数关系。研究成果对于深化高渗压、大水力梯度条件下断层破碎带和挤压带非线性渗流规律研究具有重要意义。
As more and more high-dam hydropower and high head pumped storage projects have been constructed in China, the rock foundation of high dam and high pressure water diversion system generally sustain high water pressure and hydraulic gradient. In this circumstance, not only nonlinear flow is prone to occur in rock seepage; but also accompany with leakage, seepage failure and water-inrush risk. This study experimentally investigated the nonlinear flow characteristics of broken granite rock in Yangjiang subjected to a wide range of confining pressures(1-30 MPa) through triaxial cell test system. The characteristics of nonlinear flow in broken granite rock have been elucidated; and its representation methods have been investigated. The results show that nonlinear flow occurs in the broken granite with the increasing hydraulic gradient, while the flow nonlinearity decreases with the increasing confining pressures. Combined with the cracked morphology of broken granite and the magnitude of the permeability, three possible causes triggering the nonlinear flow have been elucidated, i.e. inertial effect, seepage failure and solid-water interaction. Further, the Forchheimer and Izbash equations have been adopted to characterize the nonlinear flow, respectively, which both provide excellent description for the nonlinear flow in broken granite. The nonlinear coefficient of Forchheimer equation experience positive and negative values during the loading process, which is possibly ascribed to the closure and extension of the cracks in the broken granite. The power-law function between the nonlinear coefficients of Izbash equation has been developed by relating them with confining pressures. The results may prove useful in proper understanding of fluid flow through fault zone and compressive zone under high water pressure and hydraulic gradient.
As more and more high-dam hydropower and high head pumped storage projects have been constructed in China, the rock foundation of high dam and high pressure water diversion system generally sustain high water pressure and hydraulic gradient. In this circumstance, not only nonlinear flow is prone to occur in rock seepage; but also accompany with leakage, seepage failure and water-inrush risk. This study experimentally investigated the nonlinear flow characteristics of broken granite rock in Yangjiang subjected to a wide range of confining pressures(1-30 MPa) through triaxial cell test system. The characteristics of nonlinear flow in broken granite rock have been elucidated; and its representation methods have been investigated. The results show that nonlinear flow occurs in the broken granite with the increasing hydraulic gradient, while the flow nonlinearity decreases with the increasing confining pressures. Combined with the cracked morphology of broken granite and the magnitude of the permeability, three possible causes triggering the nonlinear flow have been elucidated, i.e. inertial effect, seepage failure and solid-water interaction. Further, the Forchheimer and Izbash equations have been adopted to characterize the nonlinear flow, respectively, which both provide excellent description for the nonlinear flow in broken granite. The nonlinear coefficient of Forchheimer equation experience positive and negative values during the loading process, which is possibly ascribed to the closure and extension of the cracks in the broken granite. The power-law function between the nonlinear coefficients of Izbash equation has been developed by relating them with confining pressures. The results may prove useful in proper understanding of fluid flow through fault zone and compressive zone under high water pressure and hydraulic gradient.
引文
[1]王媛,王飞,倪小东.基于非稳定渗流随机有限元的隧洞涌水量预测[J].岩石力学与工程学报,2009,28(10):1986-1994.WANG Yuan,WANG Fei,NI Xiao-dong.Prediction of water inflow in tunnel based on stochastic finite element of unsteady seepage[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):1986-1994.
[2]BASAK P.Steady non-Darcian seepage through embankments[J].Journal of the Irrigation and Drainage Division,1976,102(4):435-443.
[3]佘诗刚,林鹏.中国岩石工程若干进展与挑战[J].岩石力学与工程学报,2014,33(3):433-457.SHE Shigang,LIN Peng.Some developments and challenging issues in rock engineering field in China[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(3):433-457.
[4]张巍,陈云长,黄立财,等.高压隧洞内水外渗三维有限元分析与渗透稳定性研究[J].水利与建筑工程学报,2015,13(5):212-217.ZHANG Wei,CHEN Yun-chang,HUANG Li-cai,et al.3D finite element analysis of seepage from a high pressure tunnel and study on its permeation stability[J].Journal of Water Resources and Architectural Engineering,2015,13(5):212-217.
[5]CHEN Y F,HONG J M,ZHENG H K,et al.Evaluation of groundwater leakage into a drainage tunnel in Jinping-I arch dam foundation in Southwestern China:A case study[J].Rock Mechanics and Rock Engineering,2016,49(3):961-979.
[6]周毅,李术才,李利平,等.隧道充填型岩溶管道渗透失稳突水机制三维流–固耦合模型试验研究[J].岩石力学与工程学报,2015,34(9):1739-1749.ZHOU Yi,LI Shu-cai,LI Li-ping,et al.3D fluid-solid coupled model test on water-inrush in tunnel due to seepage from filled karst conduit[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(9):1739-1749.
[7]BEAR J,BACHMAT Y.Introduction to modeling of transport phenomena in porous media[M].[S.l.]:Springer Science&Business Media,2012.
[8]SMEULDERS D M J,EGGELS R,Van DONGEN M E H.Dynamic permeability:reformulation of theory and new experimental and numerical data[J].Journal of Fluid Mechanics,1992,245:211-227.
[9]SPRINGER D S,LOAICIGA H A,CULLEN S J,et al.Air permeability of porous materials under controlled laboratory conditions[J].Ground Water,1998,36(4):558-565.
[10]胡大伟,周辉,潘鹏志,等.砂岩三轴循环加卸载条件下的渗透率研究[J].岩土力学,2010,31(9):2749-2754.HU Da-wei,ZHOU Hui,PAN Peng-zhi,et al.Study of permeability of sandstone in triaxial cyclic stress tests[J].Rock and Soil Mechanics,2010,31(9):2749-2754.
[11]王伟,徐卫亚,王如宾,等.低渗透岩石三轴压缩过程中的渗透性研究[J].岩石力学与工程学报,2015,34(1):40-47.WANG Wei,XU Wei-ya,WANG Ru-bin,et al.Permeability of dense rock under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(1):40-47.
[12]WEN Z,HUANG G H,ZHAN H B.Non-Darcian flow in a single confined vertical fracture toward a well[J].Journal of Hydrology,2006,330(3):698-708.
[13]李毅.岩石裂隙的非饱和渗透特性及其演化规律研究[J].岩土力学,2016,37(8):2254-2262.LI Yi.Unsaturated hydraulic properties of rock fractures and their variation law[J].Rock and Soil Mechanics,2016,37(8):2254-2262.
[14]王媛,顾智刚,倪小东,等.光滑裂隙高流速非达西渗流运动规律的试验研究[J].岩石力学与工程学报,2010,29(7):1404-1408.WANG Yuan,GU Zhi-gang,NI Xiao-dong,et al.Experimental study of Non-Darcy water flow through a single smooth fracture[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1404-1408.
[15]刘建军,刘先贵,胡雅衽.低渗透岩石非线性渗流规律研究[J].岩石力学与工程学报,2003,22(4):556-561.LIU Jian-jun,LIU Xian-gui,HU Ya-ren.Study on nonlinear seepage of rock of low permeability[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(4):556-561.
[16]孙明贵,黄先伍,李天珍,等.石灰岩应力-应变全过程的非Darcy流渗透特性[J].岩石力学与工程学报,2006,25(3):484-491.SUN Ming-gui,HUANG Xian-wu,LI Tian-zhen,et al.Seepage properties of non-Darcy flow in complete failure process of limestone[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(3):484-491.
[17]MA D,MIAO X X,CHEN Z Q,et al.Experimental investigation of seepage properties of fractured rocks under different confining pressures[J].Rock Mechanics and Rock Engineering,2013,46(5):1135-1144.
[18]胡大伟,周辉,谢守益,等.峰后大理岩非线性渗流特征及机制研究[J].岩石力学与工程学报,2009,28(3):451-458.HU Da-wei,ZHOU Hui,XIE Shou-yi,et al.Research on character and mechacism of nonlinear seepage in post-peak marble[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(3):451-458.
[19]李顺才.破碎岩体非Darcy渗流的非线性动力学研究[博士学位论文D].徐州:中国矿业大学,2006.LI Shun-cai.Nonlinear dynamical study on non-Darcy flow in broken rock[Ph.D.Thesis D].Xuzhou:China University of Mining and Technology,2006.
[20]李天珍,马林,张连英.泥岩非Darcy流渗透特性指标正负号探讨[J].采矿与安全工程学报,2007,24(4):481-485.LI Tian-zhen,MA Lin,ZHANG Lian-ying.Discussion about positive or negative sign of permeability indexes in non-Darcy flow of mudstone[J].Journal of Mining&Safety Engineering,2007,24(4):481-485.
[21]缪协兴,陈占清,茅献彪,等.峰后岩石非Darcy渗流的分岔行为研究[J].力学学报,2003,35(6):660-667.MIAO Xie-xing,CHEN Zhan-qing,MAO Xian-biao,et al.The bifurcation of non-Darcy flow in post-failure rock[J].Acta Mechanica Sinica,2003,35(6):660-667.
[22]ZHOU J Q,HU S H,FANG S,et al.Nonlinear flow behavior at low Reynolds numbers through rough-walled fractures subjected to normal compressive loading[J].International Journal of Rock Mechanics and Mining Sciences,2015,80:202-218.
[23]CHEN Y F,ZHOU J Q,HU S H,et al.Evaluation of Forchheimer equation coefficients for non-Darcy flow in deformable rough-walled fractures[J].Journal of Hydrology,2015,529:993-1006.
[24]LIU H H,LAI B T,CHEN J H.Unconventional spontaneous imbibition into shale matrix:Theory and a methodology to determine relevant parameters[J].Transport in Porous Media,2016,111(1):41-57.
[25]李健,黄冠华,文章,等.两种不同粒径石英砂中非达西流动的实验研究[J].水利学报,2008,39(6):726-732.LI Jian,HUANG Guan-hua,WEN Zhang,et al.Experimental study on non-Darcian flow in two kinds of media with different diameters[J].Journal of Hydraulic Engineering,2008,39(6):726-732.
[26]许凯,雷学文,孟庆山,等.非达西渗流惯性系数研究[J].岩石力学与工程学报,2012,31(1):164-170.XU Kai,LIE Xue-wen,MENG Qing-shan,et al.Study of inertial coefficient of non-Darcy seepage flow[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(1):164-170.
[27]孟如真,胡少华,陈益峰,等.高渗压条件下基于非达西流的裂隙岩体渗透特性研究[J].岩石力学与工程学报,2014,33(9):1756-1764.MENG Ru-zhen,HU Shao-hua,CHEN Yi-feng,et al.Permeability of non-Darcy flow in fractured rock mass under high seepage pressure[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(9):1756-1764.
[28]CHEN Y F,HU S H,HU R,et al.Estimating hydraulic conductivity of fractured rocks from high-pressure packer tests with an Izbash’s law-based empirical model[J].Water Resources Research,2015,51(4):2096-2118.
[29]CHEN Y F,LIU M M,HU S H,et al.Non-Darcy’s law-based analytical models for data interpretation of high-pressure packer tests in fractured rocks[J].Engineering Geology,2015,199:91-106.
[30]IZBASH S V,LELEEVA N M.Aspects of turbulent seepage flow in a fill[J].Power Technology and Engineering,1971,5(5):462-465.
[31]YAMADA H,NAKAMURA F,WATANABE Y,et al.Measuring hydraulic permeability in a streambed using the packer test[J].Hydrological Processes,2005,19(13):2507-2524.
[2]BASAK P.Steady non-Darcian seepage through embankments[J].Journal of the Irrigation and Drainage Division,1976,102(4):435-443.
[3]佘诗刚,林鹏.中国岩石工程若干进展与挑战[J].岩石力学与工程学报,2014,33(3):433-457.SHE Shigang,LIN Peng.Some developments and challenging issues in rock engineering field in China[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(3):433-457.
[4]张巍,陈云长,黄立财,等.高压隧洞内水外渗三维有限元分析与渗透稳定性研究[J].水利与建筑工程学报,2015,13(5):212-217.ZHANG Wei,CHEN Yun-chang,HUANG Li-cai,et al.3D finite element analysis of seepage from a high pressure tunnel and study on its permeation stability[J].Journal of Water Resources and Architectural Engineering,2015,13(5):212-217.
[5]CHEN Y F,HONG J M,ZHENG H K,et al.Evaluation of groundwater leakage into a drainage tunnel in Jinping-I arch dam foundation in Southwestern China:A case study[J].Rock Mechanics and Rock Engineering,2016,49(3):961-979.
[6]周毅,李术才,李利平,等.隧道充填型岩溶管道渗透失稳突水机制三维流–固耦合模型试验研究[J].岩石力学与工程学报,2015,34(9):1739-1749.ZHOU Yi,LI Shu-cai,LI Li-ping,et al.3D fluid-solid coupled model test on water-inrush in tunnel due to seepage from filled karst conduit[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(9):1739-1749.
[7]BEAR J,BACHMAT Y.Introduction to modeling of transport phenomena in porous media[M].[S.l.]:Springer Science&Business Media,2012.
[8]SMEULDERS D M J,EGGELS R,Van DONGEN M E H.Dynamic permeability:reformulation of theory and new experimental and numerical data[J].Journal of Fluid Mechanics,1992,245:211-227.
[9]SPRINGER D S,LOAICIGA H A,CULLEN S J,et al.Air permeability of porous materials under controlled laboratory conditions[J].Ground Water,1998,36(4):558-565.
[10]胡大伟,周辉,潘鹏志,等.砂岩三轴循环加卸载条件下的渗透率研究[J].岩土力学,2010,31(9):2749-2754.HU Da-wei,ZHOU Hui,PAN Peng-zhi,et al.Study of permeability of sandstone in triaxial cyclic stress tests[J].Rock and Soil Mechanics,2010,31(9):2749-2754.
[11]王伟,徐卫亚,王如宾,等.低渗透岩石三轴压缩过程中的渗透性研究[J].岩石力学与工程学报,2015,34(1):40-47.WANG Wei,XU Wei-ya,WANG Ru-bin,et al.Permeability of dense rock under triaxial compression[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(1):40-47.
[12]WEN Z,HUANG G H,ZHAN H B.Non-Darcian flow in a single confined vertical fracture toward a well[J].Journal of Hydrology,2006,330(3):698-708.
[13]李毅.岩石裂隙的非饱和渗透特性及其演化规律研究[J].岩土力学,2016,37(8):2254-2262.LI Yi.Unsaturated hydraulic properties of rock fractures and their variation law[J].Rock and Soil Mechanics,2016,37(8):2254-2262.
[14]王媛,顾智刚,倪小东,等.光滑裂隙高流速非达西渗流运动规律的试验研究[J].岩石力学与工程学报,2010,29(7):1404-1408.WANG Yuan,GU Zhi-gang,NI Xiao-dong,et al.Experimental study of Non-Darcy water flow through a single smooth fracture[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1404-1408.
[15]刘建军,刘先贵,胡雅衽.低渗透岩石非线性渗流规律研究[J].岩石力学与工程学报,2003,22(4):556-561.LIU Jian-jun,LIU Xian-gui,HU Ya-ren.Study on nonlinear seepage of rock of low permeability[J].Chinese Journal of Rock Mechanics and Engineering,2003,22(4):556-561.
[16]孙明贵,黄先伍,李天珍,等.石灰岩应力-应变全过程的非Darcy流渗透特性[J].岩石力学与工程学报,2006,25(3):484-491.SUN Ming-gui,HUANG Xian-wu,LI Tian-zhen,et al.Seepage properties of non-Darcy flow in complete failure process of limestone[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(3):484-491.
[17]MA D,MIAO X X,CHEN Z Q,et al.Experimental investigation of seepage properties of fractured rocks under different confining pressures[J].Rock Mechanics and Rock Engineering,2013,46(5):1135-1144.
[18]胡大伟,周辉,谢守益,等.峰后大理岩非线性渗流特征及机制研究[J].岩石力学与工程学报,2009,28(3):451-458.HU Da-wei,ZHOU Hui,XIE Shou-yi,et al.Research on character and mechacism of nonlinear seepage in post-peak marble[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(3):451-458.
[19]李顺才.破碎岩体非Darcy渗流的非线性动力学研究[博士学位论文D].徐州:中国矿业大学,2006.LI Shun-cai.Nonlinear dynamical study on non-Darcy flow in broken rock[Ph.D.Thesis D].Xuzhou:China University of Mining and Technology,2006.
[20]李天珍,马林,张连英.泥岩非Darcy流渗透特性指标正负号探讨[J].采矿与安全工程学报,2007,24(4):481-485.LI Tian-zhen,MA Lin,ZHANG Lian-ying.Discussion about positive or negative sign of permeability indexes in non-Darcy flow of mudstone[J].Journal of Mining&Safety Engineering,2007,24(4):481-485.
[21]缪协兴,陈占清,茅献彪,等.峰后岩石非Darcy渗流的分岔行为研究[J].力学学报,2003,35(6):660-667.MIAO Xie-xing,CHEN Zhan-qing,MAO Xian-biao,et al.The bifurcation of non-Darcy flow in post-failure rock[J].Acta Mechanica Sinica,2003,35(6):660-667.
[22]ZHOU J Q,HU S H,FANG S,et al.Nonlinear flow behavior at low Reynolds numbers through rough-walled fractures subjected to normal compressive loading[J].International Journal of Rock Mechanics and Mining Sciences,2015,80:202-218.
[23]CHEN Y F,ZHOU J Q,HU S H,et al.Evaluation of Forchheimer equation coefficients for non-Darcy flow in deformable rough-walled fractures[J].Journal of Hydrology,2015,529:993-1006.
[24]LIU H H,LAI B T,CHEN J H.Unconventional spontaneous imbibition into shale matrix:Theory and a methodology to determine relevant parameters[J].Transport in Porous Media,2016,111(1):41-57.
[25]李健,黄冠华,文章,等.两种不同粒径石英砂中非达西流动的实验研究[J].水利学报,2008,39(6):726-732.LI Jian,HUANG Guan-hua,WEN Zhang,et al.Experimental study on non-Darcian flow in two kinds of media with different diameters[J].Journal of Hydraulic Engineering,2008,39(6):726-732.
[26]许凯,雷学文,孟庆山,等.非达西渗流惯性系数研究[J].岩石力学与工程学报,2012,31(1):164-170.XU Kai,LIE Xue-wen,MENG Qing-shan,et al.Study of inertial coefficient of non-Darcy seepage flow[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(1):164-170.
[27]孟如真,胡少华,陈益峰,等.高渗压条件下基于非达西流的裂隙岩体渗透特性研究[J].岩石力学与工程学报,2014,33(9):1756-1764.MENG Ru-zhen,HU Shao-hua,CHEN Yi-feng,et al.Permeability of non-Darcy flow in fractured rock mass under high seepage pressure[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(9):1756-1764.
[28]CHEN Y F,HU S H,HU R,et al.Estimating hydraulic conductivity of fractured rocks from high-pressure packer tests with an Izbash’s law-based empirical model[J].Water Resources Research,2015,51(4):2096-2118.
[29]CHEN Y F,LIU M M,HU S H,et al.Non-Darcy’s law-based analytical models for data interpretation of high-pressure packer tests in fractured rocks[J].Engineering Geology,2015,199:91-106.
[30]IZBASH S V,LELEEVA N M.Aspects of turbulent seepage flow in a fill[J].Power Technology and Engineering,1971,5(5):462-465.
[31]YAMADA H,NAKAMURA F,WATANABE Y,et al.Measuring hydraulic permeability in a streambed using the packer test[J].Hydrological Processes,2005,19(13):2507-2524.