中文摘要：

各向异性颗粒材料的变形与主应力作用方向相关。为采用离散元方法分析各向异性颗粒材料的细观变形过程,首先用2个系列的物理试验验证离散元数值模拟的可靠性和有效性。所采用的物理试验为对理想椭圆形金属棒状材料进行的不同侧向压力和不同大主应力作用方向的双轴压缩试验。在此基础上,利用离散元数值模拟可获得任意加载时刻颗粒的空间分布、运动和接触特征的优点,通过综合分析多个变形阶段颗粒的位移轨迹和旋转探讨不同大主应力方向加载时剪切带的演化过程。并进而对比剪切带内外颗粒长轴定向和孔隙的不同变化特征,发现随着变形的发展,剪切带内颗粒长轴定向趋于某一固定角度,剪切带内的孔隙比亦趋于某一定值。

英文摘要：

The deformation of granular materials with inherent anisotropy is dependent on the principal stress direction relative to the bedding plane. In order to investigate the micro deformation process of anisotropic granular materials with discrete element method（DEM）,a numerical model was verified by two series of biaxial compression tests firstly. The experiments were conducted on the ideal 2D ellipse-shaped iron rods under three cell pressures and four different major principal stress directions. On this basis, the development of shear band under four different major principal stress direction loadings was studied by analyzing the particle displacement and rotation at different deformation stages. Further,the long axis orientation of particles and void ratio inside and outside shear band were investigated. It was found that, under the loading with different major principal stress directions,the long axis orientation of particles inside the shear band tends to approach the same direction,and the same tendency was also found for the void ratio inside the shear band.