Quasistatic response of loose cohesive granular materials
Résumé
DEM-simulated model cohesive assemblies of spherical grains of diameter d , with contact tensile strength F 0 , once prepared in loose states, are quasistatically subjected to growing isotropic pressure P , and then to triaxial compression, maintaining lateral stresses σ 2 = σ 3 = P while increasing axial stress σ 1 = P + q and strain є 1 . Reduced pressure P * = d 2 P/ F 0 varies from 0.1 (cohesion dominated case, for which systems typically equilibrate with solid fraction Ф ≃ 0.35), to large values for which the cohesionless behavior is retrieved. In triaxial compression, while the moderate strain response (є 1 ~ 0.1) is influenced by initial coordination numbers and mesoscale heterogeneities, the approach to the critical state, as both q (deviator) and Ф steadily increase, gets slower for smaller P * . Critical ratio q /P strongly increases for decreasing P * , as roughly predicted in an “effective stress” scheme. Anomalously small elastic moduli are observed in the gel-like structures. While extensive geometric rearrangements take place, no shear banding is observed. Loose cohesive granular assemblies are thus capable of large quasistatic stable plastic strains and ductile rupture.
Domaines
Sciences de l'ingénieur [physics]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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