考虑颗粒棱角影响的直剪试验的离散元模拟

为了研究颗粒棱角对颗粒材料力学行为的影响，建立了具有不同棱角度的对称多面体颗粒，采用了一种简单并适合任意颗粒形状的接触本构模型，对三维离散元开源程序YADE进行了修改，研究了颗粒棱角度在模拟直剪试验中的影响以及接触力各向异性在剪切过程中的演化规律。研究结果表明，颗粒棱角度越小，颗粒间相互咬合自锁的作用越小，颗粒受剪更易转动，致使颗粒体系的剪切强度和剪胀性下降；竖向加载力越大，颗粒棱角度的影响越明显；法向接触力的各向异性在剪切过程中表现为先增后减最后趋向稳定的趋势；法向接触力的各向异性变化程度随颗粒棱角度的增大而增大。

DEM simulation of direct shear tests considering particle angularity effect

Particle shape has a significant effect on the microscopic and macroscopic mechanical behavior of granular assemblies. This paper focuses on effects of particle angularity on the mechanical behavior of granular materials and evolution of the contact force anisotropy during direct shear tests. To this end, a discrete polyhedral element model with a general contact force law for arbitrarily shaped bodies is carried out. Particle angularity is defined in terms of the sphericity and the number of vertexes of a polyhedron. Four groups of assemblies with different particle angularities consist of non-cohesive mono-sized reasonably symmetric polyhedral particles. Direct shear tests are simulated using a modified version of the open source DEM code YADE. The results show that: the granular assembly has increasing shear strength and dilatation as particle angularity increases; the effect of angularity on the shear strength and dilative behavior of assemblies is more significant as the vertical loading is larger; the anisotropy of normal contact force increases at the start, then decreasing to remain a relatively stable value during shearing; and a larger change of the anisotropy of normal contact force after shearing is corresponding to a larger angularity.