  Experiments with one-dimensional arrays of Josephson junctions in the regime
of dominating charging energy show that the Coulomb blockade is lifted at the
threshold voltage, which is proportional to the array's length and depends
strongly on the Josephson energy. We explain this behavior as de-pinning of the
Cooper-pair-charge-density by the applied voltage. We assume strong charge
disorder and argue that physics around the de-pinning point is governed by a
disordered sine-Gordon-like model. This allows us to employ the well-known
theory of charge density wave de-pinning. Our model is in good agreement with
the experimental data.
