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主要关注了颗粒材料前期所受的应力历史对其后期宏观力学响应的影响。该应力历史由一段等比例加载应力路径以及卸载垂直方向应力至与水平方向围压相同的卸载段描述。具体工作为:基于PFC2D双轴压缩数值实验,调查了应力历史对颗粒样本的强度、变形特征、细观参量如组构的影响,得出颗粒样本的偏应力-应变、体积应变曲线及其发生破坏时的名义应变云图。数值结果表明:高低围压下样本分别发生剪切破坏和弥散破坏,高围压下弹性阶段的刚度受应力历史影响较大,而低围压下样本在刚进入塑性至应力峰值点阶段的弹塑性刚度变化较为明显。随着应力历史中等比例加载系数的增大,剪胀加快,变形局部化范围有所不同;另一方面,颗粒形状的不规则性会增强颗粒材料的各向异性,导致样本强度更高。
Mainly concerned with the pre-stress of the granular material history of its macroscopic mechanical response. This stress history is described by an equal-proportionally loaded stress path and by unloading the vertical stress to the same unloading section as the horizontal confining pressure. The concrete work is as follows: Based on the numerical experiment of PFC2D biaxial compression, the influence of stress history on the strength, deformation characteristics and mesoscopic parameters such as structure of granular samples is investigated. The deviatoric stress-strain, volumetric strain curves and their occurrence Disruptive nominal strain cloud. The numerical results show that shear deformation and dispersion failure occur in the samples under the high and low confining pressure respectively. The stiffness of the elastic phase under high confining pressure is greatly affected by the stress history. However, in the case of low confining pressure, Plastic stiffness changes more obvious. With the increasing of the middle-scale loading coefficient of stress history, the dilatancy accelerates and the localization range of the deformation is different. On the other hand, the irregularity of the particle shape enhances the anisotropy of the granular material, resulting in higher sample strength.