【作者】 杨建平；

【导师】 陈卫忠；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2009， 博士

【摘要】 裂隙岩体是地质工程中经常遇到的一类复杂岩体,它的变形、强度和渗透性等特征,直接关系着工程设计、施工和运营稳定性。本文从裂隙岩体的岩石、结构面及其组合状态出发,建立岩石-结构面二元岩体模型,研究裂隙岩体的宏观变形、强度和渗透参数;并将研究成果应用到锦屏电站深埋引水隧洞工程。主要研究工作如下:(1)考虑岩石基元的非均质性,假设岩石中基元的粘聚力服从三参数Weibull分布,提出岩石的损伤模型。通过试验结果和Matlab程序拟合优化得到模型中的参数;基于建立的损伤模型和拟合优化的参数,有限元计算了不同围压下试样的轴向应力-轴向应变关系,并和试验曲线进行了对比,表明该模型可以较好地模拟不同围压下岩石的峰值强度和残余强度。建立了结构面剪切-张拉损伤演化本构模型,对所建立的结构面损伤演化模型进行了数值验证,证明了数值方法的有效性。(2)基于现场裂隙分布统计规律,用Monte Carlo法生成了随机裂隙网络。研究了岩石-结构面二元岩体模型网格生成方法,编制了Fortran程序,对裂隙岩体进行网格剖分。基于岩石和结构面的弹性参数和所建立的岩石-结构面计算网格模型,研究了岩体变形模量的尺寸效应、各向异性和张量特性,得到了裂隙岩体变形模量REV尺寸和柔度矩阵。通过理论方法研究了裂隙岩体的变形模量,结果表明该方法可以评估裂隙岩体的变形模量尺寸效应和各向异性。基于岩石和结构面的本构模型及相应的模型参数以及所建立的岩石-结构面计算网格模型,研究了裂隙岩体抗压强度的尺寸效应和各向异性,得到了岩体抗剪强度参数,并和Hoek-Brown经验准则作了对比。(3)研制了低渗透介质温度-应力-渗流耦合三轴仪(T-M-PTS),通过该仪器研究了大理岩和结构面在不同温度、不同静水压力下的渗透特性。①对大理岩进行的温度-应力-渗流耦合试验得出:在弹性受压阶段,岩石未发生热应力微破裂、未进入扩容阶段时,大理岩渗透率随着静水压力增大而降低、随着温度升高而降低。②对大理岩结构面进行的温度-应力-渗流耦合试验得出:在静水压力加载阶段,裂隙渗透率随着压力的增大而降低;在卸载过程中,由于裂隙存在不可恢复变形,渗透率不能完全恢复;静水压力不变时,裂隙渗透率随着温度升高而降低。(4)利用生成的随机裂隙网络模型,基于平行板水流立方定律和试验得到的裂隙渗透参数,通过离散裂隙网络模型研究了裂隙岩体渗透系数的尺寸效应、各向异性和张量特性,得到了渗流REV尺寸下岩体等效渗透张量。(5)将研究得到的裂隙岩体宏观力学参数代入锦屏电站引水隧洞模型,通过连续介质力学方法进行有限元计算,计算结果表明参数取值和所建模型合理。更多还原

【Abstract】 Fractured rock mass is often encounted in hydropower,mining and petroleum engineering.The deformation,strength and seepage characteristics of fractured rock mass are critical to design,construction and maintenance of rock engineering.Based on a developed rock mass model considering constitutive models of both intact rock and fracture,scale effects and hydro-mechanical parameters of rock mass are studied by numerical and analytical solutions.The main achievements are as follows:(1)The constitutive models of both intact rock and fracture are developed.Considering the heterogeneity of the rock,cohesions of units throughout the rock are supposed following a three-parameter Weibull distribution,and the cohesions decrease to zero when the units failed according to Mohr-Coulomb criterion.Parameters of the damage model are obtained through triaxial test results.On the other hand,the damage evolution law of fracture is related to magnitudes of shear displacement and normal separation.In addition, the constitutive models of rock and fracture are verified by comparing numerical results with laboratory test results.(2)Scale effects of mechanical and hydraulic properties of rock mass are studied. Firstly,the Monte Carlo simulation approach is used to generate the stochastic fracture network,based on distribution functions of location,orientation,trace-length and density of field fractures.Secondly,a reasonable approach dealing with intersection and end region of fractures is proposed,and a Fortran program is developed to generate rock mass model from the stochastic fracture network.Thirdly,based on the rock mass model,scale effect and anisotropic properties of deformation modulus of rock mass are studied according to elastic anisotropic theory.Furthermore,an analytical method is suggested to study the REV and anisotropic properties of deformation modulus of fractured rock mass.Results obtained from the method show good agreement with numerical simulation results.Finally,by implementing the constitutive models of intact rock and fracture into rock mass model, scale effect and anisotropic properties of compressive strength are evaluated.Equivalent shear strength parameters obtained from numerical simulations coincide well with strength results evaluated by empirical Hoek-Brown criterion and experience analogy.(3) A new laboratory apparatus measuring low permeability of rock in Thermo-Hydro-Mechanical coupled situation is designed and manufactured.Permeabilities of intact marble and fracture are measured under different hydrostatic stresses and temperatures.Test results show that the permeability decreases as hydrostatic stress or test temperature increases. Permeability of fracture can not resume to the previous value when hydrostratic stress returns back because of irreversible deformation.(4) Based on the generated discrete fracture network model,scale effect and anisotropy of seepage properties of rock mass are studied.Equivalent permeability tensor of fractured rock mass is obtained.(5) Based on distribution functions of fractures investigated on site,equivalent compliance matrix,equivalent shear strength parameters and equivalent permeability tensor of rock mass are obtained using the methodology proposed in the previous chapters.The parameters obtained are used to analyze the stability of diversion tunnel of Jinping hydropower station.更多还原