花岗岩断裂带原状裂隙岩水力特性试验研究
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摘要
渗透系数作为含水介质渗流测评关键指标,其变异性造成裂隙岩体地下水流动及溶质运移不确定性,影响硬岩处置库高放废物迁移、扩散等关键问题评估。针对我国高放废物处置库甘肃北山预选区旧井块段花岗岩体,以中尺度控水断裂构造为研究对象,采用非标试件渗透装置捕捉原状裂隙岩显式渗流外参分析导水性差异;染色剖分裂隙岩提取隐式过流内参重构过流网络以识别优势渗径。研究结果表明:十月井断裂损伤带内存3组裂隙,其中Ⅰ组裂隙占优的原状岩渗透系数普遍高于10~(-4) cm/s量级,导水能力最强;Ⅱ组裂隙占优的原状岩渗透系数介于10~(-5)～10~(-4) cm/s量级,导水能力居中;Ⅲ组裂隙占优的原状岩渗透系数普遍低于10~(-5) cm/s量级且多介于10~(-6)～10~(-7) cm/s之间,导水能力最弱。P-Q曲线显示此类大尺寸不规则裂隙岩水流状态多表现层流型、充填型及冲蚀型特征,其中岩样4、6、10～12呈层流型特征;岩样2、7呈充填型特征;岩样1、5、8、9、13、14则呈冲蚀型特征,冲蚀、充填、层流型曲线特征岩样其导水性能逐步递增。
Hydraulic conductivity is one of the critical parameters for evaluating flow properties of water-bearing media. The variation of this parameter generally leads to uncertainties of ground water flow and solute transport in fractured rock masses, and furthermore influences justification of important issues involving migration and diffusion of high-level radioactive wastes(HLW) in hard-rock repository. In this paper, we mainly focus on the permeability of meso-scale fault zones in granitic rock mass, which belongs to Jiujing, one of the pre-selected areas for Chinese HLW repository in Gansu Beishan. We carry out fluid flow tests on the undisturbed fractured samples collected from one of these fault zones via non-standard test apparatus and obtain the variability of hydraulic conductivity. We then realize the identification of dominant flow paths by slicing the samples and extracting internal flow parameters using staining solution. The results illustrate that three sets of fractures can be identified within the fault zone(Shiyuejing fault). Hydraulic conductivities of the fractured samples with more set I fractures are mainly over 10~(-4) cm/s, while those of samples with more set II or III fractures are respectively in the range of 10~(-5)-10~(-4) cm/s and lower than 10~(-5) cm/s, mostly 10~(-6)-10~(-7) cm/s. Permeability of the three kinds of samples thus decreases successively. Three types of flow states, namely the laminar flow type(samples 4, 6, 10-12), the infilled type(samples 2, 7), and the erosive type(samples 1, 5, 8, 9, 13, 14), are indicated by the corresponding characteristics of P-Q(pressure-flux) curves. Permeability of these three types also successively drops.
Hydraulic conductivity is one of the critical parameters for evaluating flow properties of water-bearing media. The variation of this parameter generally leads to uncertainties of ground water flow and solute transport in fractured rock masses, and furthermore influences justification of important issues involving migration and diffusion of high-level radioactive wastes(HLW) in hard-rock repository. In this paper, we mainly focus on the permeability of meso-scale fault zones in granitic rock mass, which belongs to Jiujing, one of the pre-selected areas for Chinese HLW repository in Gansu Beishan. We carry out fluid flow tests on the undisturbed fractured samples collected from one of these fault zones via non-standard test apparatus and obtain the variability of hydraulic conductivity. We then realize the identification of dominant flow paths by slicing the samples and extracting internal flow parameters using staining solution. The results illustrate that three sets of fractures can be identified within the fault zone(Shiyuejing fault). Hydraulic conductivities of the fractured samples with more set I fractures are mainly over 10~(-4) cm/s, while those of samples with more set II or III fractures are respectively in the range of 10~(-5)-10~(-4) cm/s and lower than 10~(-5) cm/s, mostly 10~(-6)-10~(-7) cm/s. Permeability of the three kinds of samples thus decreases successively. Three types of flow states, namely the laminar flow type(samples 4, 6, 10-12), the infilled type(samples 2, 7), and the erosive type(samples 1, 5, 8, 9, 13, 14), are indicated by the corresponding characteristics of P-Q(pressure-flux) curves. Permeability of these three types also successively drops.
引文
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[31]付安学.高放废物处置预选区结构面导水特性试验研究[D].南京:南京大学,2013.FU An-xue.The experimental study on hydraulic conductivity characteristics of structural plane in the preselected area for Chinese high-level radioactive waste disposal[D].Nanjing:Nanjing University,2013.
[32]纪成亮,李晓昭,王驹,等.裂隙岩体渗透系数确定方法研究[J].工程地质学报,2010,18(2):235-240.JI Cheng-liang,LI Xiao-zhao,WANG Ju,et al.Discrete fracture network model for hydraulic conductivity of fractured rock mass[J].Journal of Engineering Geology,2010,18(2):235-240.
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[2]LIU J,ELSWORTH D,BRADY B H.Linking stress-dependent effective porosity and hydraulic conductivity fields to RMR[J].International Journal of Rock Mechanics and Mining Sciences,1999,36(5):581-589.
[3]ZHAO Z,JING L,NERETNIEKS I,et al.Numerical modeling of stress effects on solute transport in fractured rocks[J].Computers and Geotechnics,2011,38(2):113-126.
[4]刘日成,蒋宇静,李树忱,等.交叉裂隙水力学开度的计算及非线性水力特性研究[J].岩土力学,2015,36(6):1581-1590.LIU Ri-cheng,JIANG Yu-jing,LI Shu-chen,et al.Study of nonlinear hydraulic characteristics and hydraulic aperture calculation of crossed fracture[J].Rock and Soil Mechanics,2015,36(6):1581-1590.
[5]PRUESS K,BODVARSSON G S,STEFANSSON V,et al.The Krafla geothermal field,Iceland:4.history match and prediction of individual well performance[J].Water Resources Research,1984,20(11):1561-1584.
[6]GUO L,LI X Z,ZHOU Y Y,et al.Generation and verification of three-dimensional network of fractured rock masses stochastic discontinuities based on digitalization[J].Environment Earth Sciences,2015,73(11):7075-7088.
[7]PETERS R R,KLAVETTER E A.A continuum model for water movement in an unsaturated fractured rock mass[J].Water Resources Research,1988,24(3):416-430.
[8]PRUESS K,WANG J S Y,TSANG Y W.On thermohydrologic conditions near high-level nuclear wastes emplaced in partially saturated fractured tuff:2.effective continuum approximation[J].Water Resources Research,1990,26(6):1249-1261.
[9]KHANG N D,WATANABE K,SAEGUSA H.Fracture step structure:geometrical characterization and effects on fluid flow and breakthrough curve[J].Engineering Geology,2004,75(1):107-127.
[10]MERRIEN S V,KORINI T,THORAVAL A.Use of an integrated discrete fracture network code for stochastic stability analyses of fractured rock masses[J].Rock Mechanics and Rock Engineering,2012,45(2):159-181.
[11]郭亮,李晓昭,周扬一,等.随机与确定耦合的裂隙岩体结构面三维网络模拟[J].岩土力学,2016,37(9):2636-2644.GUO Liang,LI Xiao-zhao,ZHOU Yang-yi,et al.Three-dimensional network simulation of fractured rock mass discontinuities based on stochastic-deterministic coupling[J].Rock and Soil Mechanics,2016,37(9):2636-2644.
[12]刘日成,蒋宇静,李博,等.岩体裂隙网络等效渗透系数方向性的数值计算[J].岩土力学,2014,35(8):2394-2400.LIU Ri-cheng,JIANG Yu-jing,LI Bo,et al.Numerical calculation of directivity of equivalent permeability of fractured rock masses network[J].Rock and Soil Mechanics,2014,35(8):2394-2400.
[13]MAZUREK M,BOSSART P,ELIASSON T.Classification and characterization of water-conducting features at?sp?:Results of investigations on the outcrop scale[R].Stockholm:[s.n.],1996.
[14]RHEN I,FORSMARK T.?sp?hard rock laboratory.High-permeability features[R].Stockholm:[s.n.],2000.
[15]BOSSART P,HERMANSON J,MAZUREK M.Analysis of fracture networks based on the integration of structural and hydrogeological observations on different scales[R].Stockholm:[s.n.],2001.
[16]耿克勤,陈凤翔,刘光廷,等.岩体裂隙渗流水力特性的实验研究[J].清华大学学报,1996,36(1):102-106.GENG Ke-qin,CHEN Feng-xiang,LIU Guang-ting,et al.Experimental research of hydraulic properties of seepage flow in fracture[J].Journal of Tsinghua University,1996,36(1):102-106.
[17]LOUIS C.Rock hydraulics in rock mechanics[M].New York:Springer-New Verlag,1974.
[18]刘日成,蒋宇静,李博,等.岩体裂隙网络非线性渗流特性研究[J].岩土力学,2016,37(10):2817-2824.LIU Ri-cheng,JIANG Yu-jing,LI Bo,et al.Nonlinear seepage behaviors of fluid in fracture networks[J].Rock and Soil Mechanics,2016,37(10):2817-2824.
[19]申林方,冯夏庭,潘鹏志,等.单裂隙花岗岩在应力-渗流-化学耦合作用下的试验研究[J].岩石力学与工程学报,2010,29(7):1379-1388.SHEN Lin-fang,FENG Xia-ting,PAN Peng-zhi,et al.Experimental research on mechano-hydro-chemical coupling of granite with single fracture[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(7):1379-1388.
[20]徐礼华,谢妮.岩石剪切裂隙渗流特性试验与理论研究[J].岩石力学与工程学报,2009,28(11):2249-2257.XU Li-hua,XIE Ni.Test and theoretical research on permeability characteristics of shear fracture in rock mass[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(11):2249-2257.
[21]杨金保,冯夏庭,潘鹏志.考虑应力历史的岩石单裂隙渗流特性试验研究[J].岩土力学,2013,34(6):1629-1635.YANG Jin-bao,FENG Xia-ting,PAN Peng-zhi.Experimental study of permeability characteristics of single rock fracture considering stress history[J].Rock and Soil Mechanics,2013,34(6):1629-1635.
[22]CHRISTOPHER A K,WILLIAM C L.A control volume model of solute transport in a single fracture[J].Water Resources Research,1995,31(2):313-322.
[23]王媛.单裂隙面渗流与应力的耦合特性[J].岩石力学与工程学报,2002,21(1):83-87.WANG Yuan.Coupling characteristic of stress and fluid flow within a single fracture[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(1):83-87.
[24]常宗旭,赵阳升,胡耀青,等.三维应力作用下单一裂隙渗流规律的理论与试验研究[J].岩石力学与工程学报,2004,23(4):620-624.CHANG Zong-xu,ZHAO Yang-sheng,HU Yao-qing,et al.Theoretic and experimental studies on seepage law of single fracture under 3D stresses[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(4):620-624.
[25]速宝玉,詹美礼,张祝添.充填裂隙渗流特性实验研究[J].岩土力学,1994,15(4):46-51.SU Bao-yu,ZHAN Mei-li,ZHANG Zhu-tian.Experimental research of seepage characteristic for filled fracture[J].Rock and Soil Mechanics,1994,15(4):46-51.
[26]王甘林,刘卫群,陶煜.充填泥沙裂隙岩石渗流特性的实验研究[J].力学与实践,2010,32(4):14-18.WANG Gan-lin,LIU Wei-qun,TAO Yu.Experimental study of permeability in fractured sandstone with sediment particles[J].Mechanics and Practice,2010,32(4):14-18.
[27]郭亮,李晓昭,王益壮,等.岩体结构均质区划分法的适用性研究[J].岩土力学,2013,34(10):2928-2937.GUO Liang,LI Xiao-zhao,WANG Yi-zhuang,et al.Applicability research on structural homogeneity delineation of rock masses[J].Rock and Soil Mechanics,2013,34(10):2928-2937.
[28]孙蓉琳,梁杏,靳孟贵.裂隙岩体渗透系数确定方法综述[J].水文地质工程地质,2006,33(6):120-123.SUN Rong-lin,LIANG Xing,JIN Meng-gui.Review on determination of hydraulic conductivity of fractured rocks[J].Hydrogeology and Engineering Geology,2006,33(6):120-123.
[29]周志芳,杨建,杨建宏.确定缓倾结构面渗透性参数的现场试验法[J].工程地质学报,1999,7(4):375-379.ZHOU Zhi-fang,YANG Jian,YANG Jian-hong.A field test method for determining permeability parameters of gently dipping structural face in rock mass[J].Journal of Engineering Geology,1999,7(4):375-379.
[30]张世殊,梁杏.平硐声波孔渗水试验确定岩体渗透系数[J].水电站设计,2002,18(1):80-82.ZHANG Shi-shu,LIANG Xing.Adit sonic wave hole seepage test to determine rock permeability coefficient[J].Hydropower Station Design,2002,18(1):80-82.
[31]付安学.高放废物处置预选区结构面导水特性试验研究[D].南京:南京大学,2013.FU An-xue.The experimental study on hydraulic conductivity characteristics of structural plane in the preselected area for Chinese high-level radioactive waste disposal[D].Nanjing:Nanjing University,2013.
[32]纪成亮,李晓昭,王驹,等.裂隙岩体渗透系数确定方法研究[J].工程地质学报,2010,18(2):235-240.JI Cheng-liang,LI Xiao-zhao,WANG Ju,et al.Discrete fracture network model for hydraulic conductivity of fractured rock mass[J].Journal of Engineering Geology,2010,18(2):235-240.
[33]ROMM E S.Flow characteristics of fractured rocks[M].Moscow:Nedra,1966.
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