离散颗粒层被横向推移过程中的力学行为研究

研究发现,颗粒物质层被匀速推移挤压过程中,所需推移力先以线性规律增加,在某一确定点后,则会以指数规律增加.而颗粒物质是由众多离散颗粒组成的软凝聚态物质,其宏观上反映的是离散颗粒的个体性质和凝聚态物质的集体效应.颗粒与颗粒之间以及颗粒与边界之间的细观尺度接触力链的构成以及演变规律将会直接影响各种宏观受力情况,其摩擦力与挤压力便是力链的主要构成形式.围绕着定量描述细观力链特征,从而揭示力的变化规律这一目标,采用计算机模拟的方法,依照球形颗粒Hertz法向接触理论和Mindlin-Deresiewicz切向接触理论,对重力作用下不同数目的三维等径球体颗粒层的推移情况进行了离散元仿真模拟,量化分析了推移力变化规律、各摩擦力变化规律以及力链分布规律,发现摩擦力与挤压力在颗粒堆积的不同阶段对力链的构成起到了不同的主次作用,使得力链发生强弱演变,从而发现了推移颗粒物质层时推移力的变化规律及原因.这些结果有利于从力链角度揭示颗粒内部和颗粒与各边界之间的受力情况.

Study on mechanical behavior of the transverse processing on a granular matter layer

When the granular matter is being pushed a certain point can be found, before arriving at which the force increases linearly, and after that it increases exponentially. The granular matter is a large assemblage of solid grains, which are fundamentally different from any other type of matters, such as solid blue and liquids; they have different physical properties. The meso-scale of force chain bridges single particles and granular matter, and leads to unique properties and behaviours of granular matters, thus acts as the key issue in the study of granular matter. In this work, we first find the variation of different forces by simulation. 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, and then point out that the change of force chain is the key to the granular dynamics. The force distribution and the force chain length distribution are calculated and analyzed to show the change rule and the origin of the drag force.
Keywords： granular matter force chain discrete element method