散粒土自然堆积的宏细观特征与形成机制

利用离散元数值方法模拟由不同形状颗粒形成散粒堆积体的过程,并通过分析堆积体的宏细观力学特征来揭示其形成机制。研究发现,颗粒形状愈规则,自然休止角愈小。细观上,颗粒接触法向量、法向接触力和切向接触力的各向异性分布强度都随颗粒形状变得规则而降低;接触法向量各向异性主方向与竖直方向的角度差■同自然休止角a之和近乎为一个常数,法向接触力和切向接触力的各向异性主方向与竖直方向的角度差■和■可近似表达为与自然休止角?正相关的线性函数。最后,建立了堆积体内部拱效应的优势发挥方位同颗粒接触法向量、法向接触力和切向接触力各向异性主方向的关系。

Macro- and micro-properties and formation mechanisms of granular piles

A DEM study is carried out to simulate the construction of granular piles by considering various particle shapes. The underlying mechanisms are analyzed through the examination of the macro and micro-characteristics of granular piles. It is found that angle of repose decreases as particle shape evolves towards a regular pattern. Microscopically, the anisotropy magnitudes of contact orientation vectors, contact normal and tangential force vectors decrease as particle shape evolves from an irregular one to a regular one. The summation of the angle difference Δ?_n between the principal anisotropy direction of contact orientation vectors and the vertical direction, with the angle of repose α, is almost a constant, and the angel differences Δ?_f and Δ?_t for the principal anisotropy directions of contact normal and tangential forces are revealed to be a linear function of angle of repose α. In addition, a relationship is also established between the direction where the most intense arching effect occurs and the principal anisotropy directions of contact orientation vectors, contact normal and tangential force vectors.