  We investigate experimentally the dynamics of an intruder dragged by a
constant force in an assembly of horizontally vibrated grains close to jamming.
At moderate packing fractions, the intruder moves rapidly as soon as the force
is applied. Above some threshold value of the packing fraction which increases
with the applied force, the intruder exhibits an intermittent creep motion with
strong fluctuations reminiscent of a crackling noise signal. These fluctuations
behave in a critical manner at the jamming transition unveilled in a previous
study. The transition separates a regime where the intruder motion is dominated
by local free volume rearrangements from a regime where the instantaneous
displacement field is strongly heterogeneous and resemble the force chains
patterns observed in dense granular packings.
