We study the internal dynamical processes taking place in a granular packing
below yield stress. At all packing fractions and down to vanishingly low
applied shear, a logarithmic creep is evidenced. The experiments are analyzed
under the scope of a visco-elastic model introducing an internal "fluidity"
variable. For all experiments, the creep dynamics can be rescaled onto a unique
curve which displays jamming at the random-close-packing limit. At each packing
fraction, a stress value is evidenced, corresponding to the onset of internal
granular reorganisation leading to a slowing down the creep dynamics before the
final yield
