Influences des param\`etres microm\'ecaniques dans la simulation num\'erique discr\`ete des mat\'eriaux granulaires : assemblage, d\'eformation quasi-statique, \'ecoulements

We review the influence of micromechanical parameters on the macroscopic mechanical behaviour of granular materials, as numerically simulated in discrete element approaches, both in quasistatic conditions an din dense flow. We insist in particular on the role of suitably defined dimensionless numbers apt to provide a classification of rheological regimes of quite general validity.