边界摩擦对二维堆积颗粒体系几何结构的影响

The Influence of boundary friction factors on geometry of two-dimensional granular systems

颗粒体系在受挤压时的受力情况和滑移通道是一个极其复杂的问题。用实验的方法研究了二维晶格堆积的颗粒体系受挤压推进过程中的力学响应和结构变化情况,观察到颗粒体系在受挤压时将出现结构的坍塌和重组行为。依据实验结果,分析了边界上压力的分布、滑移通道和重组结构与边界摩擦因素和堆积角之间的关系;用静力学理论分别讨论了处于边界和中部颗粒不同的受力机制。研究表明光滑器壁较粗糙器壁容易成为颗粒滑移的通道,这种情况下颗粒体系形成的力链不稳定,容易导致结构坍塌;边壁的摩擦不会对器壁不同高度处应力的分布产生显著影响,力链的重组才是导致不同高度处应力重新分布的主要因素。

The force situation and sliding channel are very complicated when particle system is squeezed. The mechanical response and structure changes of two-dimensional lattice pile system of granular material in the process of being pressed were experimentally investigated. The structure collapse and self-organization behavior of the particle system were observed when being squeezed. Based on the experimental results, the relationship between the horizontal pressure distribution, the sliding channel or the reorganization structure and the stacking angle as well as the boundary friction factor was discussed. According to the theory of statics, different force mechanisms about the boundary particle and the central one were analyzed. Studies have shown that compared with rough wall, smooth wall is easier to become a sliding channel for particles, so the force chain formed by the particles is unstable, which means it will easily lead to structural collapse. The friction factor on side wall wouldn＇ t have a significant impact about the stress distribution at different heights. In fact, the recombination of force chain is the main factor leading to stress redistribution at different heights.