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基于PFC2D非圆颗粒单元的二次开发,对砂土直剪力学过程进行了非圆颗粒仿真模拟,分析了数值试样的应力–剪胀关系并与实际砂土进行对比,探讨了颗粒位移与颗粒旋转特征及其与剪切带演化的内在关联,研究了主应力与主应变增量的非共轴效应,揭示了细观组构各向异性的演化规律及其与宏观剪切强度之间的宏细观关联。研究结果表明,数值试验能够较好的模拟实际砂土的应力–剪胀关系和剪切过程主应力与主应变增量的非共轴效应;剪切带的演化与颗粒位移和颗粒旋转密切相关,颗粒形状影响剪切带的厚度;试样宏观的剪切强度主要受控于粒间法向接触力的分布及其各向异性演化;整个加荷过程中,剪切带内大主应力的偏转方向与法向接触力各向异性的主方向保持了良好的一致性。
Based on the secondary development of PFC2D non-circular particle units, the non-circular particle simulation of sand-soil direct shear mechanics was carried out. The stress-dilatancy relationship of numerical samples was analyzed and compared with the actual sand. The effects of particle displacement and Particle rotation and its correlation with shear band evolution, the non-coaxial effect between principal stress and principal strain increment was studied, the evolution law of the anisotropy of the meso-structure and the relationship between the anisotropy and the macroscopic shear strength Macroscopic association. The results show that the numerical experiment can well simulate the stress-dilatancy relationship of the actual sand and the non-coaxial effect of the principal stress and the main strain increment in the shear process. The evolution of the shear band is closely related to the particle displacement and the particle rotation , The particle shape affects the thickness of the shear zone. The macroscopic shear strength of the sample is mainly controlled by the distribution and anisotropic evolution of the normal interfacial contact force. During the whole loading process, the major principal stress in the shear zone The main directions of deflection direction and the anisotropy of normal contact force maintain good consistency.