The effect of the intermediate principal stress (b quantifies its relative magnitude) on macroscale and microscale shear responses of binary granular mixtures with different fines contents (FCs) was investigated using the discrete element method. Mixtures were made up of coarse particles with real gravel shapes and fine particles with sphere shapes. True triaxial compression tests were conducted on their dense specimens. The shapes of coarse particles play an important role in the peak and critical friction angles and the peak dilatancy angles of binary granular mixtures. For mixtures with different FCs and an identical b, there is a linear relationship between the peak friction angle (or peak dilatancy angle) and the change in the void ratio. An acceptable equation was proposed to predict the peak dilatancy angle of a mixture. When b = 0.2 and 0.4, the coaxiality of strain increments and stresses is affected by the FC. A previous study classified mixtures as “underfilled”, “interactive-underfilled”, “interactive-overfilled” and “overfilled” based on the percentage contributions of coarse–coarse, coarse–fine and fine–fine contacts to the shear strength. This study shows that the b value has little effect on the classification of mixtures at the peak and critical states. Furthermore, it was observed that there is a linear relationship between the relative peak dilatancy angle and the difference between the partial coordination numbers based on the “subsphere–subsphere” approach at the peak and critical states.

使用离散元方法研究了中间主应力（b量化了其相对大小）对具有不同细粉含量（FCs）的二元颗粒混合物的宏观和微观剪切响应的影响。混合物由具有真实砾石形状的粗颗粒和具有球形形状的细颗粒组成。对它们的致密样品进行了真正的三轴压缩试验。粗颗粒的形状在二元颗粒混合物的峰和临界摩擦角以及峰膨胀角中起着重要作用。对于具有不同FC和相同b的混合物，峰值摩擦角（或峰值剪胀角）与空隙率的变化之间存在线性关系。提出了一个可接受的方程式来预测混合物的峰值膨胀角。当b  = 0.2和0.4时，应变的同轴度和应力会受到FC的影响。之前的研究根据粗，粗，粗，细和细密接触对剪切强度的贡献百分比将混合物分类为“欠填充”，“交互式欠填充”，“交互式过量填充”和“过量填充”。这项研究表明，b值对峰值和临界状态下的混合物分类几乎没有影响。此外，观察到相对峰膨胀角与基于峰和临界状态下的“亚球-亚球”方法的部分配位数之间的差之间存在线性关系。