基于离散元模拟的二元颗粒柱坍塌特性研究

常见的地质灾害如滑坡、泥石流、岩崩等通常都涉及不同形状的颗粒物质运动,这些形状不同的颗粒又多具有不同的尺寸和含量。基于典型的颗粒柱坍塌试验,首先根据试验方法确定了离散元模拟所需的各项参数,然后采用随机多面体方法生成了可控制长细比的大颗粒,利用离散元法就不同大颗粒含量下形态变化对二元颗粒柱坍塌特性的影响开展研究,研究结果表明:(1)利用离散元法可以较好地重现室内试验中小球和多面体组成的二元颗粒系统的颗粒柱坍塌过程;(2)在不同长细比的不规则大颗粒和小球组成的二元颗粒柱系统中,当大颗粒含量高于临界含量值20%时,二元颗粒柱坍塌持续的时间随非球形大颗粒长细比的增加而增加;(3)在不同长细比的不规则大颗粒和小球组成的二元颗粒柱中,当大颗粒含量高于临界含量值20%时,在相同百分比的大颗粒含量下,大颗粒长细比的增加会提高大颗粒平均配位数以及降低颗粒的运动能力,大颗粒间形成更强的互锁作用,降低了颗粒柱的整体流动性,使其最终堆积高度更高、最大跑出距离更短以及更小的归一化动能峰值。(4)在不同长细比的不规则大颗粒和小球组成的二元颗粒柱中,小颗粒可以较为明显降低大颗粒间摩擦及互锁作用,增加流动性,降低大骨料形态对坍塌过程的影响。

Research on collapse characteristics of binary particle column based on discrete element simulation

Common geological disasters such as landslides, mudslides, rock slides, etc. usually involve the movement of particles of different shapes, and most of these particles have different sizes and contents. Based on a typical particle column collapse test, the parameters required for the discrete element simulation were first determined according to the test method, and then the random polyhedron method was used to generate large particles with a controllable slenderness ratio. After that, the discrete element method was used to determine the contents of different large particles. The effect of morphological changes on the collapse characteristics of the binary particle column was then studied. The results of the study showed that:(1) The discrete element method could better reproduce the collapse process of the binary particle system composed of small spheres and polyhedrons in laboratory experiments;(2) In a binary particle column system composed of irregular large particles and small balls with different slenderness ratios, when the content of large particles was higher than the critical content of 20%, the duration of the collapse of the binary particle column varied with the non-spherical large particles;(3) In a binary particle column composed of irregular large particles and small balls with different slenderness ratios, when the content of large particles was higher than the critical content value of 20%, under the same percentage of large particle content, the increase of the slenderness ratio of the large particles increased the average coordination number of the large particles and reduced the movement ability of the particles. A stronger interlocking effect was formed between the large particles, which reduced the overall fluidity of the particle column and made the column finally pile up to a higher height, a shorter maximum distance and a smaller normalized kinetic energy peak;(4) In the binary particle column composed of irregular large particles and small balls with different slenderness ratios, small particles could significantly reduce the friction and interlocking effect between large particles, increase fluidity, and reduce the impact of large aggregate shape on the collapse process.