Usually, fundamental studies concerning the behavior of granular media under vibrations are performed on monodisperse spherical particles located in a 2D container. In this work, polydisperse sand particles are placed in a 3D cylindrical container with a protocol allowing reproducible reference packings. These packings are then submitted to vertical mechanical vibrations. First of all a phenomenological study has been made for describing the shape of the sand packing under vibration as a function of both the adimensional acceleration, and the frequency for a container of given size. Then the dependence of the packing behavior on the diameter and the height of sand have been analyzed. Results show that whatever the frequency and the acceleration used an increase of the diameter and an increase of the height of initial sand packing in the container reduce the expansion.