Abstract：Stochastic granule discontinuous deformation(SGDD) model is presented from mesomechanical view；random distribution model of rockfill granule is built by Monte Carlo method；and nonlinear contact algorithm is presented based on modified augmented Lagrangian algorithm. SGDD model may simulate effectively interaction of rockfill granule and tip rupture. Triaxial samples of rockfill are simulated by SGDD model；and the movement and deformation processes of rockfill granule also re-emerge. The numerical calculation results show that SGDD model can simulate the instantaneous deformation process. Scale effect of laboratory test for rockfill is also discussed. Two groups of rockfill samples，a reduced scale gradation and another real one，are simulated by SGDD model. It reveals that the real scale gradation shows less deformation and higher initial modulus of elasticity under the same axial stress and confining pressure without considering creep and humidification deformations of rockfill.
