Particle breakage during shearing of a carbonate sand

Abstract

A series of ring shear tests was conducted to investigate the development of particle breakage with shear strain for a carbonate sand. It was found that at very large displacements the soil reached a stable grading, but that the final grading was dependent on both the applied normal stress and the initial grading. The particle breakage caused a volumetric compression, which again ceased only when the stable grading had been attained, emphasising that critical states as observed at much smaller strains in triaxial tests are not rigorously defined. Despite the severe degradation of the soil particles the mobilised angle of shearing resistance was found not to change significantly.Nous avons mené une série d'essais de cisaillement annulaire afin d'enquêter sur le développement des cassures de particules avec une déformation de cisaillement pour un sable carbonate. Nous avons trouvé qu'avec de très importants déplacements, le sol parvenait à une granulométrie stable mais que la granulométrie finale dépendait de la contrainte normale appliquée et de la granulométrie initiale. La cassure des particules provoque une compression volumétrique qui, encore une fois, ne cesse que lorsque la stabilité granulométrique est atteinte, soulignant le fait que les états critiques tels que ceux qui sont observés avec des déformations bien plus petites dans les essais triaxiaux ne sont pas rigoureusement définis. Nous avons trouvé que malgré la dégradation sévère des particules de sol, l'angle mobilisé de résistance au cisaillement ne changeait pas de manière significative.

Bonded-cell model for particle fracture

“…Both single-particle crushing and fragmentation process of an assembly of particles subjected to shearing or compaction have been subject to experimental investigations in civil engineering and particle technology [10][11][12][13][14][15][16][17][18][19][20][21][22]. The compressive strength of a single particle, its variability, and size dependence are essential for understanding the collective response of a granular material to applied loading.…”

Breakage of an artificial crushable material under loading

“…A number of recent detailed studies have considered the relationship between particle crushing and soil mechanical behaviour ( [1,[3][4][5]4,7,9,23,25,28,36]). From the point of view of constitutive modelling, the question to be addressed is how microscopic degradation phenomena, such as grain crushing, affect the macroscopic properties of a granular aggregate, ideally deducing macroscopic constitutive equations from micromechanical consideration of some underlying microscopic process [25].…”

Discussion: Shear strength of cohesionless soils at low stress

“…It may be concluded that particle breakage continues to very large strains (7500%), far beyond those reached in the direct shear tests reported in the paper (16-25%). Coop et al (2004) concluded that at very large strains a constant grading should be reached, but that constant grading is dependent not only on the normal stress applied but also on the uniformity and absolute particle size of the initial grading (Fig. 15).…”