【作者】 赵延林；

【导师】 曹平；

【作者基本信息】 中南大学 ， 岩土工程， 2009， 博士

【摘要】 渗流场中裂隙岩体的力学特性及水岩作用机理一直是岩石力学领域关注的前沿方向。渗流场的存在和改变是导致裂隙岩体工程失稳,甚至导致大规模地质灾害的重要原因之一。裂隙渗透压加剧了岩体裂隙的起裂、扩展、贯通,导致岩体渐进失稳破坏,在宏观上,这一过程也是渗流导致岩体强度劣化损伤和围岩应力场变化的过程,另一方面岩体应力的改变和岩体裂隙的损伤扩展,导致裂隙岩体渗透特性变化,将改变渗流场分布。岩体应力的损伤演化与渗流之间的耦合作用可称为裂隙岩体渗流—损伤—断裂耦合,裂隙岩体渗流—损伤—断裂耦合理论在水利水电工程、采矿工程、边坡工程、隧道工程等领域有广泛的应用前景。本文研究课题依托国家自然科学基金资助项目(50774093):水岩作用下裂隙岩体流变—损伤—断裂耦合理论及应用。研究渗透压作用下裂隙岩体断裂力学特性,采用断裂损伤力学理论研究渗流—应力共同作用下裂隙岩体的损伤变形和断裂破坏,从实验研究、理论分析和数值模拟多方面对裂隙岩体渗流—损伤—断裂之间的耦合机理进行了深入系统研究。重点研究了渗透压对裂隙岩体宏细观结构的改造作用及其宏观损伤力学响应;围绕裂隙岩体渗流—损伤—断裂耦合机理和应用研究这一课题,开展以下方面的研究工作:(1)研究渗流—应力作用下岩石裂纹的压剪起裂、翼形裂纹扩展、贯通规律;首次建立了渗流—应力作用下的压剪翼形裂纹模型并对模型进行有限元数值验证;建立了渗流—压剪应力作用下岩石多裂纹体的损伤断裂力学模型和裂纹贯通的破坏准则,从理论上揭示了岩体水力致裂裂缝扩展行为规律。(2)类岩材料多裂纹体断裂破坏实验与岩石断裂韧度测试。用白水泥砂浆作为相似材料,采用预埋抽条法制作不同空间展布的类岩石裂隙模型试样,对单轴加载下裂隙扩展、贯通方式及强度损伤随裂隙空间展布和裂隙数量变化规律进行了探索;对多系列岩石试件断裂韧度进行双扭实验测试,发现岩石断裂度与杨氏模量存在线性关系。(3)采用细观力学方法研究渗流—应力共同作用下裂隙岩体的损伤变形,综合岩体初始损伤和损伤演化特性,建立了裂隙岩体渗流—损伤—断裂耦合本构模型及裂隙岩体渗透张量演化方程;研制了含水裂隙岩体峰前应力—应变的细观损伤力学的计算程序WFRD~2D。(4)从岩体结构力学出发,在建立孔隙—裂隙岩体介质的流固耦合精细模型的基础上,提出了基于双重介质裂隙岩体渗流—损伤—断裂耦合的数学模型,该模型中渗流场对损伤场的耦合效应不仅体现在水力梯度以体积力或面力形式作用在应力计算单元上,还体现在渗透压对裂隙岩体刚度矩阵的削弱上。损伤应力场对渗流场的耦合作用体现在岩体和裂隙的渗透系数是应力、翼形裂纹扩展长度和裂隙张开度的函数上,该耦合模型中主干裂隙渗流采用离散介质渗流模型;断续裂隙网络渗流采用拟连续介质渗流模型。(5)研制了双重介质渗流—损伤—断裂耦合模型的有限元程序DSDFC.for。提出离散裂隙介质在进行应力分析时采用空间节理单元,在进行渗流分析时采用平面四节点等参单元或三角形单元的离散方法:保证了不同介质之间的水量交换和两类模型接触处结点水头,位移相等。(6)在FLAC~3D现有计算模块的基础上,通过FISH研制裂隙岩体渗流—损伤—断裂耦合计算程序(扩展FLAC~3D模型)。开发的计算程序具有强大数值功能,包含了损伤力学计算模块、渗流计算模块及双场耦合分析模块。(7)将裂隙岩体渗流—损伤—断裂耦合模型应用于水库蓄水裂隙岸坡的稳定性分析和不衬砌压力隧洞工程中,分析不同蓄水时期,裂隙岸坡渗流场分布、损伤场的演化,探讨了水库蓄水过程中岸坡山体变形机制。耦合分析认为:山体变形是增量渗透力和增量浮托力共同作用于岸坡的结果;对蓄水相对高程较大的裂隙岸坡而言,库水位上升,裂隙渗透水压增加导致岩体裂纹起裂扩展,岩体损伤区增大且向岸坡深部扩展。高渗透压诱发岸坡不利断层带损伤区扩展,甚至贯通可能是导致岸坡失稳的重要原因。研究了不衬砌水工压力隧洞在运行期间的水力劈裂情况、渗流场分布和内水外渗情况,首次提出陡倾地表下不衬砌压力隧洞与裂纹几何特性、力学特性和岩石断裂韧度高度相关的水力劈裂系数的概念。(8)高压预注水致裂软化煤层的工业实验和数值研究。潞安矿务局王庄煤矿3#煤层4309工作面煤层进行高压预注水致裂软化煤层的工业实验,提出了该煤层注水软化顶煤方案。注水方案的实施使王庄矿中硬煤综放面顶煤放出率提高17%,粉尘浓度降低56%,产量提高45%,创造了显著经济效益。采用渗流—损伤—断裂耦合理论从渗流力学和岩石力学的角度对煤层注水过程中煤体的润湿过程、煤岩的变形及煤岩损伤区等进行了系统的数值研究;得出高渗透水压作用下煤岩裂隙结构的断裂损伤演化是高压预注水软化煤层的基本力学原理。更多还原

【Abstract】 The mechanical properties of fractured rock masses in the seepage field and mechanism of water-rock interaction have become one of front direction concerned with rock mechanics field.The exist and change of seepage field is one of important reasons for the instability of rock masses engineering,even leads to large-scale geological disasters.With aggravating the branch cracks seeding,propagation and coalescence,seepage pressure in fractures leads to progressive failure of rock engineering.In the macro level,this process is also the process that seepage lead to the damage of rock mass strength,on the other hand,the change of rock mass stress field and the damage propagation of rock fractures cause the change of seepage properties and accordingly change seepage field distribution.Coupling effect of damage evolution of rock mass stress and seepage can be called coupling of seepage-damage-fracture in fractured rock masses.Coupling theory of seepage-damage-fracture in fractured rock masses has a good prospect of engineering application in the field of hydropower engineering,mining engineering slope engineering and tunnel engineering.The studied title is come from National Science Foundation Project （grant number:50774093）:Coupling theory of rheology-damage -fracture in fractured rock masses and application under water-rock interaction.Using fracture and damage mechanism theory,the paper has researched the fracture mechanic property of fractured rock masses,and damage deformation of fractured rock masses under the action of seepage-stress.The paper has systematic studied seepage-damage-fracture coupling mechanism with the method of experimental study, theoretical analysis and numerical simulation,the research has focused on the subject of transformation effect of micro-macro analysis structure of fractured rock masses and macroscopic damage mechanical response of fractured rock masses under the action of seepage pressure.Around coupling theory of seepage-damage-fracture in fractured rock masses and application,the paper has carried out the research work involving several aspects as follows:（1）Study the rules of compression shear fracture of rock cracks,the wing cracks propagation and the rock bridge coalescence.The.wing cracks model subjected to compression-shear stress under the action of seepage-stress has been established firstly and the FEM numerical validation is aslo demonstrated.The damage fracture mechanics model and the fracture failure criterion of rock multi-crack body has been established.theoretically,the crack propagation subjected to rock mass hydraulic fracture has been revealed.（2）The macro-mechanical experiments on regular cracks body in rock-like materials and the test on rock fracture toughness have been made.Using white cement as the similar materials,the rock-like specimens in which the cracks were arranged in different echelon design through pre-installed steel slice were produced,the research on the models of fracture propagation and coalescence,as well as the law of strength variation with the cracks collocation and crack numbers under uniaxial loading were summarized systematically.The fracture toughness of multi-series rock specimens were measured by using the double torsional method,The results showed that there was a linear relation between rock fracture toughness and young modulus.（3）Using micromechanics theory,the paper has studied the laws of damage deformation of fractured rock masses subjected to the action of seepage-stress.Synthetically considering initial damage and damage evolution of rock mass,the constitutive model of seepage-damage-fracture coupling in fractured rock masses and permeability tensor evolution equation have been established,the meso-damage mechanics calculation program WFRD^2D for the stress-strain behavior of water-bearing fractured rock masses at the pre-peak has been developed.（4）From the aspect of rocks structure mechanics.based on the fluid-solid coupling model of fine pore-fissure rock media,the dual mida model for seepage-damage-fracture coupling in fractured rock masses has been put forworded.The coupling effect of seepage field on damage field not only is embodied by the fact that hydraulic gradient acts on stress calculation unit as body force or face force,but also the fact that the seepage pressure weakens element stiffness matrix.The coupling effect of damage field on seepage field is embodied by the fact that the permeability coefficients of the rocks and fractures depend on the stress,the wing cracks length.In coupling model,the discrete hydromechanical model is used to simulate fracture seepage,the equivalent-continuum model of seepage is used to simulate fracture network seepage in rock masses.（5）Finite element program DSDFC.FOR for the dual mida model for seepage-damage-fracture coupling in fractured rock masses has been developed,the 3D jointed elements are used to simulate discrete jointed rock mass during the stress analysis of discontinuities and 2D isoparametric elements are used to simulate discontinuities during seepage analysis of discontinuities,So the different media can exchange water,and water head,displacement of nodes which are in the interface between two models are equal.（6）Baesd on FLAC^3D existing computation modules,the programs of seepage-damage-fracture coupling(extended FLAC^3D model) in fractured rock masses has been developed.The developed calculation program has powerful numerical calculation function,including damage mechanics calculation module,seepage calculation module and double-field coupled calculation module.（7） The theory of seepage-damage-fracture coupling was applied to the fractured rock bank slope during the rising of water level in reservoir and unlined pressure tunnels.The laws of the distribution of the seepage field and damage field evolution in the fractured rock bank slope are obtained during the impoundment process of the reservoir.A preliminary study on deformation of bank slope during the rising of water level in reservoir also is made.Coupling Analysis holds that deformation of bank slope is due to the interaction of increment seepage force and increment uplift force.For the fractured bank slope with the hight relative elevation of water storage,the increase of seepage pressure in fractures lead to damage zone growth with starting-crack and fracture propagation occuring.High seepage pressure leads to damage zone growth in unfavorable fault zone and even transfixion may be the important reasons which result in bank slope instability.the paper also has studied the hydraulic splitting state,the distribution of the seepage field and the inner water leaking in unlined pressure tunnels.The hydraulic splitting safety factor of pressure tunnel under inclined ground is proposed firstly.The hydraulic splitting safety factor is in high correlation with geometric characteristics and mechanical characteristics of rock cracks and rock fracture toughness.（8） Industrial experiment on pressure water injection into coal to fracturing and weakening top coal and numerical study of the progress of coal seam water infusion were developed.Industrial experiment of pressure water injection into coal on the working face 4309 of fully mechanized sublevel caving mining in Lu’an Wangzhuang Mine were developed.The plan of weakening top coal by using water pre-infusion were put forward.The implementation of weakening top coal by using water pre-infusion made the coal face recovery impove 17%,dust concentration decrease 56%,production increase 45%,increased economical benefits of enterprise.The theory of seepage-damage-fracture coupling was applied to pressure water injection into coal,the laws of the coal seam water infusion course,coal mass deformation and damage field evolution in coal rock have systematic studyied form the aspects of seepage mechanics and rock mechanics.The mechanical principle in pressure water injection into coal to fracturing and weakening top coal lies in fracture damage evolution of fissure structure of coal rock subjected to high seepage pressure.更多还原