Experimental Stick-Slip Behaviour In
Triaxial Test on Granular Matter
Abstract: This paper is concerned
with the quasi-static rheology of packings of glass spheres of diameter d
(d=0.2mm, 0.7mm or 3mm). Stick-slip behaviour is observed on small spheres, i.e
d=0.2mm & 0.7mm ; one observes also in this case a weakening of the
rheology as the rate of deformation increases, and the larger the rate the
larger the weakening; this generates macroscopic instabilities and stick-slip. Statistics
of stick-slip events have been determined, which show that the larger the
sample the more regular (i.e. "periodic") the sick-slip, the faster
the strain rate the less periodic the events. One concludes that this
stick-slip is generated at the macroscopic level and comes from the macroscopic
rhelogical law. However when sample is small, local fluctuations perturb the
macroscopic events and trigger them erratically.
Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn
poudres & grains 12 (7), 115-121 (octobre 2001)