Investigating the Dynamic Instabilities of Model Granular Materials in Isotropic Consolidation and Triaxial Drained Compression

Abstract

This paper reports the dynamic instabilities of model granular materials under isotropic consolidation and triaxial drained axisymmetric compression. Loose and fully saturated samples of mono sized glass beads exhibit in isotropic drained compression a series of local collapses under undetermined stress and even liquefaction in some rare cases. Stick-slip phenomenon occurs in drained compression, and even rare liquefaction happens for the first slip. These dynamic instabilities (collapse, liquefaction and stick-slip) of loose granular assembly can share the same physical driving mechanisms with strong links to geometrical features, i.e. the collapse of the structural metastable honeycombed macropores or the propagation of the local failures of the force chains; even if the unambiguous identification of the triggering mechanisms is still unknown. The experimental data eliminates the excess pore fluid as the primary cause.