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Discrete-element method (DEM) simulations of three-dimensional (3D) assemblies of ellipsoid particles were used to evaluate the critical state (CS) for both drained and undrained (constant volume) conditions. A series of conventional triaxial cyclic liquefaction tests with symmetrical cyclic deviatoric stress () with initial were simulated to develop a relationship between the cyclic stress ratio () and the number of cycles required for initial liquefaction (), where is the mean effective normal stress at the end of consolidation. Both cyclic mobility and instability type behaviors were observed depending on the initial void ratio () and . The micromechanics quantities, i.e., the coordination number (), von Mises fabric (), fabric anisotropy intensity (), and stress-strain behavior, suggested that cyclic mobility and instability may depend on the phase transformation and instability state, respectively. The cyclic resistance ratio …