静态堆积颗粒中的力链分布

颗粒物质是由众多离散颗粒组成的软凝聚态物质，涉及多个物理层次结构和机制，是多尺度问题. 首先阐述了颗粒物质多尺度力学的研究框架，指出颗粒间接触力链构成的细观尺度是核心，颗粒物质显示出的独特静态堆积特性和动态流变特性都与细观尺度力链的复杂演变规律直接相关. 围绕着定量描述力链特征这一目标，采用严格的球形颗粒Hertz法向接触理论和Mindlin-Deresiewicz切向接触理论，对重力作用下12000个球心共面的二维等径颗粒静态堆积进行了离散动力学模拟，对力链分布特征、接触力规律等做了量化分析，考察了颗粒 关键词： 颗粒物质 力链 离散模型 多尺度力学

Force distribution in static granular matter in two dimensions

Granular matter is a large assemblage of individual solids, which is fundamentally different from any other type of matters, such as solid and liquid. The intrinsic nature of granular matter is of multi-scale, inclusive of microscale of particle size, mesoscale of force chain and macroscale of the bulk of granular matter. The mesoscale of force chain bridges single particle and granular matter, and leads to unique properties and behaviours of granular matters, and thus acts as the key issue in the study of granular matter. In this work, we firstly propose a multiscale methodology for granular matter dynamics, and point out that the characteristics of force chain is the key to the granular dynamics. We then propose a discrete element model based on rigorous Hertzian contact law and Mindlin-Deresiewicz contact theory for normal and tangential contact forces, respectively. The static packing of 12000 sand grains under the action of gravity in two dimensions is simultaed, and the force chain pattern and stress distribution are obtained. The force distribution, force chain length distribution and the angle distribution are calculated and analyzed. Friction coefficient of particle is found to be a very sensitive factor affecting properties of granular matter, and thus its influence on the above parameters is studied as well.