Snow avalanches are a major hazard in mountainous areas and have a significant impact on infrastructures, economy and tourism of such regions. Obtaining a thorough understanding on the pressure exerted by avalanches on infrastructures is crucial for the development of design criteria so that they can withstand avalanche impact. Avalanches are characterized by two main pressure regimes depending on flow dynamics and snow properties: in the inertial regime the pressure is proportional to velocity, while in the gravitational regime it is proportional to flow depth. Today, the knowledge on avalanche impact relies mostly on empirical equations and it is not clear yet how to describe the coefficients of proportionality, namely the drag coefficient and the amplification factor in the inertial and gravitational regimes, respectively. In order to investigate the origin of these coefficients, we developed a Discrete Element Model (DEM) capable of resolving the three-dimensional avalanche flow field around a generic infrastructure.