中文摘要：

尾矿的力学特性与粉粒含量有关，但目前对粉粒含量的影响机制研究较少。为了研究粉粒含量对尾矿力学性质的影响及其细观机制，通过显微观测、三轴试验和离散元模拟，研究砂粒和粉粒的显微特征，分析尾矿的临界粉粒含量，并讨论粉粒含量效应的细观力学机制。结果表明：砂粒和粉粒在粒径分布、棱角性和表面形貌方面存在差异，粒径小于30μm的颗粒具有独特的显微特征；随着粉粒含量的增加，混合尾矿逐渐由砂性尾矿过渡到粉性尾矿，临界粉粒含量在30％-50％范围；理论推导证明，粉粒的粒径和弹性模量越小，相同力作用下的土体形变越大：从介观上看，粉粒含量的增加弱化了原有的强力链，是导致粉粒含量效应的重要原因。研究结果揭示了混合尾矿的细观力学行为机制，为宏细观关联性研究提供了参考。

英文摘要：

The mechanical properties oftailings are affected by the silt content, but so far, studies related to the influence mechanism of silt content on the mechanical properties are not much. This paper presents the investigation on the effects of silt content on the mechanical property of tailings and its mesoscopic mechanism. The microscopic observation, the triaxial test and the discrete element simulation were performed to study the microscopic characteristics of sand and silt. The critical silt content is analyzed based on the results of the experiment. Finally, we proposed a mesoscopic mechanism of silt content effect. The silt and sand particles are different in size distribution, angularity and surface topography. The tiny particles（〈30 μm） have the unique microscopic features. The sandy tailing is transformed into the silty tailing with the increase of silt content, and the critical content is 30% - 50%. It is theoretically proved that the smaller of silt particle size and the elastic modulus are, the bigger the deformation of soil is. Mesoscopically, the increase of salt content weakens the original force chain, thus resulting in the silt content effect.