(1. Faculty of Civil Engineering and Mechanics，Kunming University of Science and Technology，Kunming，Yunnan 650500，China；2. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：To study the seepage and dissolution coupling mechanisms of rough rock fractures，the pricewise linear method is adopted to generate the fracture surface and the fractal dimension is utilized to characterize the roughness. A lattice Boltzmann model，applying the double distribution function to respectively simulate the evolutions of velocity field and concentration field and assuming that the dissolution at the fracture surface satisfies the first-order dynamic reaction model，is proposed to simulate the coupling mechanism considering the effect of surface reaction. The validity of the proposed model is verified by two classical examples，and the effects of the fractal dimension，Pe number and Da number on the seepage and dissolution coupling mechanism of rough fractures are discussed. The results show that the larger the fractal dimension is，the slower the solute transport is，which results in a slower dissolution rate at the fracture surface. The dissolution occurs preferentially at the raised position of fractures，which makes the surface smooth gradually. When the Pe number is larger，the seepage velocity is relatively higher，which promotes the solute transport and the dissolution reaction，causes the surface geometry flattening and increases the permeability. The larger the Da number is，the faster the dissolution rate at the entrance is，which leads to more undissolved parts accumulated at the end of the fracture when the porosity is the same and affects the permeability of the fracture.
[1] 田智威，谭云亮. 含喉部裂隙介质CO2反应迁移的格子Boltzmann模拟研究[J]. 岩土力学，2017，38(3)：663–671.(TIAN Zhiwei，TAN Yunliang. Lattice Boltzmann simulation of CO2 reactive transport in throat fractured media[J]. Rock and Soil Mechanics，2017，38(3)：663–671.(in Chinese))
[2] KANG Q，ZHANG D，CHEN S，et al. Lattice Boltzmann simulation of chemical dissolution in porous media[J]. Physical Review E，2002，65(3)：036318.
[3] CUBILLAS P，KÖHLER S，PRIETO M，et al. How do mineral coating affect dissolution rates? An experimental study of coupled CaCO3 dissolution-CdCO3 precipitation[J]. Geochimica Et Cosmochimica Acta，2008，69(23)：5 459–5 476.
[4] 霍吉祥，宋汉周，杜京浓，等. 表面反应和扩散迁移联合控制的粗糙单裂隙渗流—溶解耦合模型[J]. 岩石力学与工程学报，2015，34(5)：1 013–1 021.(HUO Jixiang，SONG Hanzhou，DU Jingnong，et al. Coupled fluid flow and chemical dissolution model based on surface reaction and mass transfer control in a rough fracture[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(5)：1 013–1 021.(in Chinese))
[5] 盛金昌，徐孝臣，姚德生，等. 流固化学耦合作用下裂隙岩体渗透特性研究进展[J] 岩土工程学报，2011，33(7)：996–1 006. (SHENG Jinchang，XU Xiaochen，YAO Desheng，et al. Advances in permeability evolution in fractured rocks during hydro-mechanical- chemical processes[J]. Chinese Journal of Geotechnical Engineering，2011，33(7)：996–1 006.(in Chinese))
[6] 周 辉，汤艳春，胡大伟，等. 岩盐裂隙渗流-溶解耦合模型及试验研究[J]. 岩石力学与工程学报，2006，25(5)：946–950.(ZHOU Hui，TANG Yanchun，HU Dawei，et al. Study on coupled penetrating-dissolving model and experiment for salt rock cracks[J]. Chinese Journal of Rock Mechanics and Engineering，2006，25(5)：946–950.(in Chinese))
[7] 冯夏庭，丁梧秀. 应力–水流–化学耦合下岩石破裂全过程的细观力学试验[J]. 岩石力学与工程学报，2005，24(9)：1 465–1 473. (FENG Xiating，DING Wuxiu. Meso-mechanical experiment of microfracturing process of rock under coupled mechanical- hydrological- chemical environment[J]. Chinese Journal of Rock Mechanics and Engineering，2005，24(9)：1 465–1 473.(in Chinese))
[8] 盛金昌，李凤滨，姚德生，等. 渗流–应力–化学耦合下岩石裂隙渗流特性试验研究[J]. 岩石力学与工程学报，2012，31(5)：1 016–1 025.(SHENG Jinchang，LI Fengbin，YAO Desheng，et al. Experimental study of seepage properties in rocks fracture under coupled hydro-mechano-chemical process[J]. Chinese Journal of Rock Mechanics and Engineering，2012，31(5)：1 016–1 025.(in Chinese))
[9] DETWILER R L，GLASS R J，BOURCIER W L，et al. Experimental observations of fracture dissolution：The role of Peclet number on evolving aperture variability[J]. Geophysical Research Letters，2003，30(12)：1 648.
[10] 张贵金，徐卫亚，赖 苗. 溶蚀岩体的溶渗作用及岩溶坝区的渗透性研究[J]. 岩土力学，2003，24(5)：795–799.(ZHANG Guijin，XU Weiya，LAI Miao. Leaching of solution rock and permeability study under karst-engineering geological condition[J]. Rock and Soil Mechanics，2003，24(5)：795–799.(in Chinese))
[11] 王锦国，周志芳，陈松峰. 观音岩水电站坝址区右岸岩体溶蚀发育机制研究[J]. 工程地质学报，2011，19(3)：409–416.(WANG Jinguo，ZHOU Zhifang，CHEN Songfeng. Corrosion mechanism of rock mass at dam site left bank of Guanyinyan hydropower station [J]. Journal of Engineering Geology，2011，19(3)：409–416.(in Chinese))
[12] 梁卫国，赵阳升. 岩盐水压致裂连通溶解的数学模型[J]. 太原理工大学学报，2002，33(4)：361–363.(LIANG Weiguo，ZHAO Yangsheng. Mathematical model of hydraulic fracture connection and solution mining in salt deposit[J]. Journal of Taiyuan University of Science and Technology，2002，33(4)：361–363.(in Chinese))
[13] LIU J，SHENG J，POLAK A，et al. A fully-coupled hydrological- mechanical-chemical model for fracture sealing and preferential open[J]. International Journal of Rock Mechanical and Mining Sciences，2006，43(1)：23–36.
[14] 速宝玉，张文捷，盛金昌，等. 渗流–化学溶解耦合作用下岩石单裂隙渗透特性研究[J]. 岩土力学，2010，31(11)：3 361–3 366. (SU Baoyu，ZHANG Wenjie，SHENG Jinchang，et al. Study of permeability in single fracture under effects of coupled fluid flow and chemical dissolution[J]. Rock and Soil Mechanics，2010，31(11)：3 361–3 366.(in Chinese))
[15] 孙旭曙，王科峰，柴军瑞，等. 岩体裂隙网络矿物溶解–沉淀–迁移数值模拟[J]. 水文地质工程地质，2011，38(6)：84–89.(SUN Xushu，WANG Kefeng，CHAI Junrui，et al. Numerical simulation of mineral dissolution-precipitation-transportation in a fracture network of rock-mass[J]. Hydrogeology and Engineering Geology，2011，38(6)：84–89.(in Chinese))
[16] DETWILER R L，RAJARAM H. Predicting dissolution patterns in variable aperture fractures：Evaluation of an enhanced depth- averaged computational model[J]. Water Resources Research，2007，43：W04403.
[17] 谭云亮，尹延春，滕桂荣，等. 基于Lattice Boltzmann方法的瓦斯渗流模拟研究[J]. 煤炭学报，2014，39(8)：1 446–1 454.(TAN Yunliang，YIN Yanchun，TENG Guirong，et al. Simulation research of gas seepage based on Lattice Boltzmann method[J]. Journal of China Coal Society，2014，39(8)：1 446–1 454.(in Chinese))
[18] 王 刚，黄 娜，蒋宇静，等. 考虑分形特征的节理面渗流计算模型[J]. 岩石力学与工程学报，2014，33(增2)：3 397–3 405. (WANG Gang，HUANG Na，JIANG Yujing，et al. Seepage calculation model for rough joint surface considering fractal characteristics[J]. Chinese Journal of Rock Mechanics and Engineering，2014，33(Supp.2)：3 397–3 405.(in Chinese))
[19] KANG Q，LICHTNER P C，ZHANG D. An improved lattice Boltzmann model for multcomponent reactive transport in porous media at the pore scale[J]. Water Resources Research，2007，43(12)：2 578–2 584.
[20] CHEN L，KANG Q，VISWANATHAN H S，et al. Pore-scale study of dissolution-induced changes in hydrologic properties of rocks with binary minerals[J]. Water Resources Research，2014，50(12)：9 343–9 365.
[21] 张 婷，施保昌，柴振华. 多孔介质内溶解与沉淀过程的格子Boltzmann方法模拟[J]. 物理学报，2015，64(15)：154701.(ZHANG Ting，SHI Baochang，CHAI Zhenhua. Lattice Boltzmann simulation of dissolution and precipitation in porous media[J]. Acta Phys. Sin，2015，64(15)：154701.(in Chinese))
[22] QIAN Y H，D?HUMIERES D，LALLEMAND P. Lattice BGK Models for Navier-Stokes Equation[J]. Europhysics Letters，1992，17(6)：479–484.
[23] ZHANG T，SHI B，GUO Z，et al. General bounce-back scheme for concentration boundary condition in the lattice Boltzmann method[J]. Physical Review E，2012，85(2)：016701.
[24] GUO Z L，ZHENG C G，SHI B C. Non-equilibrium extrapolation method for velocity and pressure boundary conditions in the lattice Boltzmann method[J]. Chinese Physics，2002，11(4)：366–374.
[25] LEE Y H，CARR J R，BARR D J，et al. The fractal dimension as a measure of the roughness of rock discontinuity profiles[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1990，27(6)：453–464.
[26] SAUTY J P. An analysis of hydrodispersive transfer in aquifers[J]. Water Resources Research，1980，16(1)：145–158.
2019, Vol. 38 
