In this paper a theoretical and numerical study of impulsive loads over a granular medium free surface has been developed. We will model a real case, as a high deformable solid impacting a less deformable surface, and consequently subject to micro and macro medium failure. Developing a macroscopic approach we resolve the macro-stress in the homogenized two-dimensional medium and subsequently apply a representative volume element (RVE) analysis modeling to the micro-scale. The problem is developed by energetic approach on an elasto-plastic element using an energy functional containing bulk and surface contributions. Finally, a numerical application is presented.