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针对圆形和单粒组颗粒模拟试验的缺陷,基于PFC2D的clump命令,开发了非圆形颗粒组,采用单向法、各向同法和沉积法生成不同初始组构特征的试验样品,模拟了砂土直接剪切试验过程.探讨了初始组构各向异性对砂土抗剪强度与剪胀性的影响规律,研究了剪切过程中力链的演化形式,分析了颗粒旋转以及剪切带内外颗粒长轴定向的变化特征.数值试验结果表明:颗粒初始组构的差异对抗剪强度的影响较大,对材料的剪胀性以及内摩擦角的影响较小;剪切过程应力主轴发生了偏转,颗粒接触角向主应力方向靠拢;颗粒旋转主要发生在8倍于平均颗粒半径的条带内,颗粒长轴定向也发生了偏转,偏转方向与主应力偏转方向相同,但滞后于主应力的偏转速度;初始组构的不同影响剪切带内颗粒的旋转速度.
Aimed at the defects of the circular and single-particle particle simulation experiments, based on the clump command of PFC2D, a non-circular particle group was developed. The test samples with different initial structures were generated by one-way method, isotropic method and deposition method. The process of direct shear test of sand was discussed.The influence of initial anisotropy of anisotropy on shear strength and dilatancy of sand was discussed.The evolution of force chain in shear process was studied.The particle rotation and shearing The experimental results show that the difference of the initial structure of the particles has a great influence on the shear strength and has little effect on the dilatancy of the material and the internal friction angle. The shear stress principal axis And the contact angles of the particles move closer to the principal stress. Particle rotation mainly occurs in the strip with 8 times the average particle radius. The long axis orientation of the particles also deflects, and the deflection direction is the same as that of the principal stress but lags behind The deflection speed of the principal stress; the difference of the initial structure influences the rotation speed of the particles in the shear band.