We report on the quasistatic behaviour of model granular materials, as probed by DEM simulations of isotropic compression and triaxial compression tests, focussing on the macroscopic behaviour dependence on control parameters expressed in dimensionless forms that combine contact laws with test conditions, and on the influence of the initial state. A discussion of the microscopic origins of strain, which in some situations of small strains and stable contact networks are due to contact deflections, and in other cases results from the continuous breaking and repairing of networks under varying loads provides a useful classification of rheological regimes. Some guidelines for parameter choices in numerical simulations, and for some homogenization approaches, are inferre
