Particle damage observed in ring shear tests on sands

Abstract

In this paper, particle damage of three test sands with different mineralogical compositions is studied using stress–displacement response measured in ring shear tests, particle-size distributions of the original sand prior to shear and from the shear band after shear, and by examining particle shape changes determined by scanning electron microscope. Particle damage during shearing produced a wider particle-size distribution, and damage typically continued until the normal stress was small (about 28 kPa) in constant volume ring shear tests and the internal stresses were distributed among sufficient particle contacts such that damage practically ceased. The dominant damage mechanism (typically either particle abrasion and shearing-off asperities or particle splitting) depended strongly on the soil response (i.e., contraction or dilation), particle hardness, and particle-size distribution, but both mechanisms produced particles that were more angular and rougher than the original sand particles. The magnitude of particle damage observed in the ring shear tests was influenced by the consolidation normal stress, shear displacement, particle mineralogy, particle-size distribution, drainage conditions, and soil fabric (in constant volume tests). Lastly, the influence of particle damage on engineering properties including hydraulic conductivity, liquefaction resistance, stress–strain response, friction angle, and critical state are briefly discussed.

Altered marine tephra deposits as potential slope failure planes?

“…The strength of volcanic ash is related to particle roughness and angularity as previously observed in common sands (Mair et al 2002;Sadrekarimi and Olson 2010). Strengthening due to roughness and angularity is partly expressed in the apparent cohesion and friction angle (Fig.…”

Stress-strain behavior of sand at high strain rates

“…Structural weaknesses in larger grains due to possible presence of more flaws and anomalies in individual grains can lead to more crushing in coarse grains compared to finer grains [54e56]. Recent studies suggest that crushing in coarse angular grains under shear consists of shearing-off of asperities, whereas finer grains fracture along their natural cleavage planes [52]. Moreover, stress concentration on individual grains plays an important role in damage and grain fracture, and has been studied by several authors [54,56].…”

Influence of mannitol concentration on the physicochemical, mechanical and pharmaceutical properties of lyophilised mannitol

“…From Figure 3, it can be seen that LM particles produced steeper decreases in sizes as a function of the increase in sonication time as compared to CM. Due to their increased angularity (Figure 1, SM-2), LM particles could have increased damage caused because of stress (Sadrekarimi and Olson, 2010). Therefore, in comparison to CM, LMs demonstrated considerably higher relative degrees of breakage (RDB), with the RDB increasing with decreasing mannitol concentration (Figure 3).…”