title: Evidence of mechanically activated processes in slow granular flows.
abstract: We study how a shear band in a granular medium dramatically changes the mechanical behavior of the material further in the non sheared region. To this end, we carry out a microrheology experiment, where a constant force F is applied to a small rod immersed outside the shear band. In the absence of a shear band, a critical force F(c) is necessary to move the intruder. When a shear band exists, the intruder moves even for a force F less than the critical force F(c). We systematically study how the creep velocity V(creep) of the rod varies with F(c) - F and with the distance to the shear band, and show that the behavior can be described by an Eyring-like activated process.
authors.affiliation: IUSTI, CNRS UMR 6595, Université Aix Marseille, 5 rue Enrico Fermi, 13465 Marseille Cedex 13, France.
authors.forename: K A
authors.initials: KA
authors.lastname: Reddy
authors.forename: Y
authors.initials: Y
authors.lastname: Forterre
authors.forename: O
authors.initials: O
authors.lastname: Pouliquen