中文摘要：

基于二维颗粒流软件,采用2种不同算法生成clump和cluster模型,研究细观参数和结构（结晶颗粒大小形状分布、预制微裂纹）对宏观力学特性的影响,量化宏细观参数对应关系,探讨微裂纹发展演化规律及试件破坏的细观机制。研究表明：（1）2种模型生成算法各有优势,圆形区域标记法模型力学特性随细观参数变化规律性较好,波动较小,搜索算法能较好地控制结晶级配组成;（2）单轴抗压强度UCS、抗拉强度TS与clump半径、无黏结比例（随机分布微裂纹）呈指数函数变化,与黏结强度比呈幂次函数关系;弹性模量、泊松比与上述三细观参数均呈线性变化,且二者变化趋势相反;UCS/TS比值随clump半径、黏结强度比、cluster黏结强度比值n、无黏结比例的增加而增大,且黏结强度比对其影响最大;张拉裂纹比例受黏结强度比影响最大,clump半径影响次之;（3）单轴压缩下试件以张拉破坏为主,张拉裂纹优势导向主要沿轴向扩展,剪切裂纹则主要沿与轴向夹角20°~40°扩展,巴西劈裂试样张拉破坏裂纹均贯穿试件中心。clump与cluster模型微裂纹扩展演化过程及破坏模式差异较大,相比cluster模型,clump模型剪切裂纹比例相对较大,裂纹破碎带更宽,破裂面粗糙不平整。

英文摘要：

Clump and cluster models based on two-dimensional particle flow code（PFC2D） were constructed through two different algorithms to explore the effects of micro parameters and microstructure（crystal grain size and distribution,pre-existing cracks） on the macro mechanical properties of specimen and to quantify the relationships between them. Meanwhile,the development of micro cracks and the mechanism of micro failure were studied. It was revealed that two algorithms had their own advantages. Macro mechanical properties of marked circular region algorithm changed with the variation of micro parameters nicely. The composition of crystalline gradation was better controlled by the searching algorithm. The uniaxial compressive strength（UCS） and the tensile strength（TS） are in exponential relationship with the clump radius and un-bonded ratio（random pre-existing cracks） and are in power relationship with the bond strength ratio. The elastic modulus and Poisson？s ratio are in linear relationship with the clump radius,bond strength ratio and un-bonded ratio. With the increase of the clump radius,bond strength ratio,bond strength ratio n of cluster and un-bonded ratio,the ratio of uniaxial compressive strength to tensile strength which is mostly affected by bond strength ratio increases a lot. The ratio of tensile cracks is mostly affected by the bond strength ratio,followed by the clump radius. Under the uniaxial compression,the failure of specimen is dominated by the tensile cracks which mainly extend along the axial direction. However,the angle between the dominant orientation of shear cracks and axis is 20 degree to 40 degree. Brazil test failure is dominated by tensile cracks across the center of specimen. The evolution of micro cracks and failure modes are different for cluster and clump models. Compared with the cluster model,the shear crack ratio of clump model is bigger and crack crushing zone is wider. Moreover,the fracture surface is more rough and uneven.