Static and dynamic features of granular material failure due to upward pulling of a buried sphere by a slowly increasing force
Static and dynamic features of granular material failure due to upward pulling of a buried sphere by a slowly increasing force
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由于缓慢增加的力向上拉动埋藏球体导致颗粒材料失效的静态和动态特征
DOI：
10.1039/d0sm01914c
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发表时间：
2021
期刊：
影响因子：
3.4
通讯作者：
Socolar, Joshua E.
中科院分区：
文献类型：
--
作者：
Jalali, Payman;Zhao, Yuchen;Socolar, Joshua E.
一个球形入侵者嵌入在一个有限的颗粒柱提取通过拉它向上的一个附加字符串。随着弦的张力逐渐增加，在一定的拉力下发生故障事件，导致入侵者快速向上加速。使用渥太华砂和玻璃珠，对不同填充高度和柱直径的临界力和失效事件的动力学进行了实验研究。对于渥太华砂，我们发现破坏力可以用描述在一个圆锥体中颗粒材料重量的模型来拟合，该圆锥体的顶点在侵入体的底部，顶角为72°。模型和实验之间的协议是好的高度小于柱（管）直径，但测量值偏离模型的高度更大。我们还报告了玻璃珠的实验，揭示了意想不到的效果，相对较小的比例管直径的晶粒尺寸。动态的入侵者在故障事件的研究，使用高速视频分析。对于足够大的管直径，颗粒曳力在拉出过程中单调衰减。在窄列，单调衰减的阻力失败后，观察到低的高度，而第二个峰值可以看到在足够深和窄列，表明存在不同的机制失败。在小位移范围内，所有管径的标准化阻力都随侵入位移的增大而减小。
A spherical intruder embedded in a confined granular column is extracted by pulling it upward by an attached string. As the tension of the string gradually increases, a failure event occurs at a certain pulling force, leading to rapid upward acceleration of the intruder. The threshold force and the dynamics of the failure event are experimentally investigated for different filling heights and column diameters, using Ottawa sand and glass beads. For the Ottawa sand, we find that the failure force can be fit by a model describing the weight of the granular material in a cone with the vertex at the bottom of the intruder and a vertex angle of 72°. The agreement between the model and experiments is good for heights less than the column (tube) diameter, but measured values deviate from the model for larger heights. We also report on experiments with glass beads that reveal unexpected effects for relatively small ratios of tube diameters to grain size. The dynamics of the intruder during the failure event is studied using high-speed video analysis. The granular drag force monotonically decays during the pullout for sufficiently large tube diameters. In narrow columns, a monotonic decay of drag force after failure is observed for low heights, whereas a secondary peak can be seen in sufficiently deep and narrow columns, indicating the existence of different mechanisms of failure. The normalized drag force declines with intruder displacement closely for all tube diameters within small displacements.