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碎石颗粒的形状对于集料的整体剪切性能有很大的影响,而现有的研究缺乏对于不规则块体颗粒形状的定量评价指标。利用离散元软件PFC2D(Particle flow code,2D)研究,提出了不规则块体的生成方法,建立了平面双轴剪切试验条件,通过对比室内试验结果完成了对模型的验证以及细观参数的选择。通过对块体进行分割后得到的多边形相邻顶角的差值进行分析,改进了棱角度指数的概念,在此基础上分析了颗粒形状对于级配不良的碎石集料的力学性质的影响,研究结果表明:棱角度指数受划分边界数的影响较大,随着划分密度的增加,棱角度指数不断减小并趋于稳定;随着轴向应变的增加,碎石集料的剪应力呈现出明显的非线性增加,曲线的形态受颗粒形状影响较大,除球形颗粒外,其他形状颗粒集料均呈现出应变硬化的特性。在棱角度指数较低时,抗剪强度和内摩擦角缓慢增加,而当棱角度较大时,抗剪强度指标则增加较快,可以通过幂函数进行拟合。
The shape of the gravel particles has a great influence on the overall shear properties of the aggregates. However, the existing research lacks the quantitative evaluation index of the shape of the irregular block particles. Using the discrete element software PFC2D (Particle Flow Code, 2D), the method of generating irregular blocks was proposed and the plane biaxial shear test conditions were established. The verification of the model and the comparison of the mesoscopic parameters select. By analyzing the difference between the adjacent vertexes of the polygons obtained after the block is divided, the concept of the angularity index is improved. Based on the analysis, the influence of particle shape on the mechanical properties of graded aggregates with poor grading is analyzed The results show that the angularity index is greatly affected by the boundary number, and as the densification density increases, the angularity index decreases and tends to be stable. With the increase of axial strain, the shear stress of aggregate Showing a significant nonlinear increase, the shape of the curve is greatly affected by the particle shape, except for the spherical particles, the other shape of the particle aggregates showed a strain hardening characteristics. When the degree of angularity is low, the shear strength and internal friction angle slowly increase, while when the degree of angularity is large, the shear strength index increases rapidly and can be fitted by power function.