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Evolution of particle morphology and mode of fracture during the oedometric compression of sand
Géotechnique ( IF 5.8 ) Pub Date : 2020-12-14 , DOI: 10.1680/jgeot.18.p.300
Dawa Seo 1 , Changbum Sohn 1 , Mehmet B. Cil 2 , Giuseppe Buscarnera 1
Affiliation  

This work uses synchrotron X-ray tomography to quantify the role of the particle shape on the interaction between collective comminution and individual grain fracture. Two sands (subrounded Ottawa and subangular Q-ROK#2) were compressed beyond their comminution pressure and imaged at the microscale. An algorithm was developed to track the sequence of breakage events stemming from compression, as well as the evolving morphology of the resulting fragments. The results show that the degree of grain shape evolution depends on the initial morphology of the particles, with subrounded particles exhibiting the most severe shape alterations. However, it was found that at high compressive stress all morphological indices approach similar values. Such a tendency is achieved when crushing involves primarily the finer grain fractions – that is, when cushioning hinders the rupture of larger particles. A quantitative assessment of the mode of particle failure also revealed that in both sands comminution (i.e. the pervasive fragmentation of individual particles) was not achieved abruptly, but was rather attained by way of successive stages of splitting and chipping. These findings suggest that in crushable granular solids the initial grain shape plays a key role during the first stages of compression leading to yielding, but its influence tends to vanish at higher pressures, when cushioning mitigates the impact of initial morphological differences and hinders further major breakage.

中文翻译:

砂土定形压缩过程中颗粒形态和断裂模式的演变

这项工作使用同步加速器 X 射线断层扫描来量化颗粒形状对集体粉碎和单个晶粒断裂之间相互作用的作用。两个沙子(近圆形的渥太华和亚角 Q-ROK#2)被压缩到超过它们的粉碎压力并在微尺度上成像。开发了一种算法来跟踪由压缩引起的断裂事件的序列,以及所得碎片的演变形态。结果表明,颗粒形状演变的程度取决于颗粒的初始形态,亚圆形颗粒表现出最严重的形状变化。然而,发现在高压缩应力下所有形态指数接近相似值。当粉碎主要涉及更细的颗粒部分时,就会出现这种趋势 - 即,当缓冲阻碍较大颗粒的破裂时。颗粒失效模式的定量评估还表明,在两种砂中,粉碎(即单个颗粒的普遍破碎)不是突然实现的,而是通过连续的分裂和碎裂阶段实现的。这些发现表明,在可压碎的颗粒固体中,初始颗粒形状在导致屈服的压缩的第一阶段起着关键作用,但它的影响在更高的压力下往往会消失,因为缓冲减轻了初始形态差异的影响并阻止了进一步的重大破碎. 单个颗粒的普遍破碎)不是突然实现的,而是通过分裂和碎裂的连续阶段实现的。这些发现表明,在可压碎的颗粒固体中,初始颗粒形状在导致屈服的压缩的第一阶段起着关键作用,但它的影响在更高的压力下往往会消失,因为缓冲减轻了初始形态差异的影响并阻止了进一步的重大破碎. 单个颗粒的普遍破碎)不是突然实现的,而是通过分裂和碎裂的连续阶段实现的。这些发现表明,在可压碎的颗粒固体中,初始颗粒形状在导致屈服的压缩的第一阶段起着关键作用,但它的影响在更高的压力下往往会消失,因为缓冲减轻了初始形态差异的影响并阻止了进一步的重大破碎.
更新日期:2020-12-14
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