For a single soilbag filled with a cohesionless granular material analytical and numerical models based on a continuum approach are used to predict the evolution of deformation and stress under monotonic compression and plane strain conditions. Analytical models with different assumptions for the stress ratio distribution in filling material, a constant volume and a frictionless interface between the soil and the wrapping bag are studied. In order to evaluate the simplifications assumed for the analytical model numerical simulations are carried out with a micro-polar hypoplastic model for the soil behavior and an elastic-ideally plastic model for the wrapping material. Particular attention is paid to the influence of the interface behavior between the soil and the bag material on the evolution of state quantities. The special cases of a frictionless interface and an interlocked interface are investigated. Results show that the assumed interface behavior influences the evolution of the state quantities and the location of zones with intense strain localization of the granular material.