We propose, in this paper, a model for predicting the rheological response of both vibrated and sheared 3D granular suspensions in stationary and nonstationary conditions. The major assumption of this model is the inherent bimodal behavior of chain forces in granular packings. The model is set up from a kinetic equation describing the dynamic exchange between a population of strongly correlated caged particles and a population of slightly correlated free particles. To compare the predictions of the model to experimental results, the kinetic equation is transformed into a differential constitutive equation, relating stress to strain, by including the effect of the interstitial fluid on the suspension. With only four adjustable parameters intrinsic to the system (i.e., independent of the type of rheological test used), the model is in very close agreement with experiments. Despite the fact that our approach remains at a mean-field level, it is able to predict and describe several rheological behaviors, in stationary, nonstationary conditions, linear and nonlinear regimes, including Newtonian and frictional Coulombian regimes, as well as elastic Hookean and viscoelastic Maxwellian behaviors. It then appears that this two-state approach allows capturing both the viscoelastic behavior of dry granular materials and granular suspensions. Vibrated dense suspensions and granular media are thus unified under a common framework.