We discuss the application of a recently developed theory of multiphase mixtures to fluid‐saturated granular materials. The theory includes the incompressibility of each phase, but unlike other theories of the type, does not require pressure equilibrium between the phases. We do a theoretical study of the motion of this material in a viscometric simple shearing apparatus. It is shown that simple shearing generally does not occur. Typically, in the vicinity of a boundary, if the solid volume fraction is low, a layer of high shear rate occurs, while if the solid volume fraction is high, a ‘‘locking’’ phenomenon occurs. Otherwise, there is a tendency for particles to accumulate in regions of low shear rate.