  We present a numerical implementation of an active inclusion in a granular
material submitted to a biaxial test. We discuss the dependence of the response
to this perturbation on two parameters: the intra-granular friction coefficient
on one hand, the degree of the loading on the other hand. We compare the
numerical results to theoretical predictions taking into account the change of
volume of the inclusion as well as the anisotropy of the elastic matrix.
