  When submitted to a constant mechanical load, many amorphous solids display
power law creep followed by fluidization. A fundamental understanding of these
processes is still far from being achieved. Here, we characterize creep and
fluidization on the basis of a mesoscopic viscoplastic model that includes
thermally activated yielding events and a broad distribution of energy
barriers, which may be lowered under the effect of a local deformation. We
relate the creep exponent observed before fluidization to the width of barrier
distribution and to the specific form of stress redistribution following
yielding events. We show that Andrade creep is accompanied by local
strain-hardening driven by stress redistribution and find that the fluidization
depends exponentially on the applied stress. The simulation results are
interpreted in the light of a mean-field analysis, and should help in
rationalizing the creep phenomenology of amorphous solids.
