  Using numerical simulations, we examine the dynamics of active matter
run-and-tumble disks moving in a disordered array of obstacles. As a function
of increasing active disk density and activity, we find a transition from a
completely clogged state to a continuous flowing phase, and in the large
activity limit, we observe an intermittent state where the motion occurs in
avalanches that are power law distributed in size with an exponent of $\beta =
1.46$. In contrast, in the thermal or low activity limit we find bursts of
motion that are not broadly distributed in size. We argue that in the highly
active regime, the system reaches a self-jamming state due to the
activity-induced self-clustering, and that the intermittent dynamics is similar
to that found in the yielding of amorphous solids. Our results show that
activity is another route by which particulate systems can be tuned to a
nonequilibrium critical state.
