  We show that Zhang's sandpile model (N,[a,b]) on N sites and with uniform
additions on [a,b] has a unique stationary measure for all 0 <= a < b <= 1.
This generalizes earlier results where this was shown in some special cases.
  We define the infinite volume Zhang's sandpile model in dimension d >= 1, in
which topplings occur according to a Markov toppling process, and we study the
stabilizability of initial configurations chosen according to some measure \mu.
We show that for a stationary ergodic measure \mu with density \rho, for all
\rho < 1/2, \mu is stabilizable; for all \rho >= 1, \mu is not stabilizable;
for 1/2 <= \rho < 1, when \rho is near to 1/2 or 1, both possibilities can
occur.
