  Any infinite sequence of substitutions with the same matrix of the Pisot type
defines a symbolic dynamical system which is minimal. We prove that, to any
such sequence, we can associate a compact set (Rauzy fractal) by projection of
the stepped line associated with an element of the symbolic system on the
contracting space of the matrix. We show that this Rauzy fractal depends
continuously on the sequence of substitutions, and investigate some of its
properties; in some cases, this construction gives a geometric model for the
symbolic dynamical system.
