断续裂隙岩体各向异性流变特性及微细观时效破裂机理

Rock masses with intermittent joints are widespread in the engineering, and development of joints often lead to instability and destruction of the dam, slope and underground cavern of engineering rock masses. Due to the existence of fissures, hard rock under high in-situ stresses often shows time-dependent characteristics. Rock masses with intermittent cracks in underground projects are taken as the research object, the rheological deformation characteristics, long-term strength and microscopic rupture mechanism will be studied by means of rheological tests, microscopic experiment, theoretical analysis and numerical simulation. Intermittent joints with spatial distribution will be prefabricated in specimens of real rock and rock-like materials, and rheological tests will be performed on aotumatic triaxial rheological machine. The rheological properties and fracture mechanism will be studied under various conditions(different fissure spacings, different fissure lengths, different lengths of the rock bridge, different fissure inclinations). Influence rules of the different confining pressures, fracture distribution patterns and stress paths on the creep deformation and long-term strength will be analyzed. The anisotropic rules of rheological parameters will be investigated. Based on the triaxial rheological tests of intermittent fractured hard rock under complex stress paths, the nonlinear rheological model which reflects the rheological characteristics and time-dependent damage rupture criteria will be established by theories of rheological mechanics, damage mechanics and visco-elasto-plastic mechanics. Microscopic tests of the fractured rock by scanning electron microscopy will be taken to reveal the structure rheological evolution. By secondary development of PFC, the rheological numerical model of the rock masses with intermittent cracks will be built up, and microscopic numerical simulation of multi-factors and multi-conditions will be taken to reveal the time-dependent deformation and rupture evolution of intermittent cracked rock masses. This work will provide theory and applied basic research for the evaluation to long-term stability of rock engineering.

断续节理裂隙岩体在工程中广泛存在，节理裂隙的发育常常导致大坝、边坡和地下硐室等工程岩体的失稳与破坏。拟以地下工程裂隙岩体为研究对象，运用室内流变试验、理论分析和数值模拟等方法，研究断续裂隙岩体的各向异性流变特性及流变破裂机制。在真实岩石和类岩石材料的试块中预制出空间分布的断续裂隙，采用全自动三轴流变仪，对预制裂隙岩体在加卸载条件下进行流变试验。研究多工况（不同裂隙间距、裂隙长度、岩桥长度、裂隙倾角）的断续裂隙岩体流变力学特性与破裂机理，探讨断续裂隙空间分布形态对流变变形和长期强度的影响，分析流变力学参数的各向异性规律。基于试验结果，采用流变力学、损伤力学、黏弹塑性力学理论，建立岩石非线性各向异性流变力学模型。对离散元PFC进行二次开发，建立断续裂隙岩体流变特性的数值模型，并进行多因素多工况的细观数值模拟，揭示断续裂隙岩体的流变破裂演化规律；为岩石工程的长期稳定性评价提供理论依据和应用基础。

断续裂隙在工程岩体中广泛存在，极大程度的影响大坝、边坡和地下硐室等工程岩体的失稳与破坏。以往的研究中，对于多断续裂隙岩体的力学性质研究多集中于其瞬时力学性质的研究，而对其时效力学行为和渐近性破坏规律尚缺少合理的力学模型及数值模拟解释。.以地下工程裂隙岩体为研究对象，运用室内流变试验、现场剪切流变试验分析、理论模型建立和数值模拟等方法，研究了断续裂隙岩体的流变特性及流变破裂机制。主要成果如下：.1、在类岩石材料的试块中预制出空间分布的断续裂隙，采用全自动三轴流变仪，对预制裂隙岩体在加载条件下进行了瞬时压缩试验和流变试验。通过正交设计试验研究了裂隙间距、裂隙长度、岩桥长度、裂隙倾角对峰值强度、弹性模量等参数的影响规律：各因素对试样峰值强度影响的主次顺序依次是裂隙倾角、裂隙长度、岩桥长度和裂隙间距；进行了断续裂隙岩体单轴压缩蠕变试验，获得了多裂隙岩体渐近性破坏的试验数据，得到了断续裂隙扩展贯通导致试样整体破坏的时效破坏规律。.2、从细观角度，采用颗粒流程序PFC2D计算分析了不同裂隙分布形式的裂隙扩展贯通规律。建立断续裂隙岩体流变特性的离散元数值模型，并进行多因素多工况的细观数值模拟，探讨了断续裂隙岩体的流变破裂演化规律。同时，基于有限差分程序FLAC3D，提出一个基于损伤的渐近性破坏模型，并对该模型进行了二次开发嵌入到FLAC3D中，较好的模拟了多裂隙岩体的蠕变破裂特征和裂隙演化规律。.3、从宏观角度，基于蠕变试验的变形特征，建立了一个新的非线性黏弹塑性流变模型，提出用屈服接近度作为三维蠕变分段函数的判别标准，该模型可以很好地描述岩石的衰减蠕变、等速蠕变特别是加速蠕变的三阶段蠕变变形特性。结合裂隙岩体的现场剪切蠕变试验，辨识了相应的蠕变力学模型，并进行了参数反演，分析了现场岩体的蠕变力学行为，为工程岩体的长期稳定性评价提供了基础。.基于项目研究成果发表期刊论文8篇，其中SCI检索论文2篇（International Journal of Rock Mechanics and Mining Sciences, Rock Mechanics and Rock Engineering），EI检索论文6篇，申请发明专利12项，已授权发明专利6项，按计划完成了既定研究内容和任务，达到了预期研究目标。