ABSTRACT
Several reasons explain the considerable difficulties encountered in the theoretical study of the behaviour of materials stored in silos, during both filling and discharge. First of all, the rheology of ensiled materials is very complex, very poorly understood, and affected by many parameters. For example, the response of a granular material to a given loading depends on the intensity of the applied stresses, their orientation and direction, the rate of loading, and even the stress history. It also varies with the density of the material and with the arrangement of the particles. In addition, the strains are very often concentrated in narrow shear bands, which are difficult to model. Again, the problem of silos is most often three-dimensional, which makes the numerical calculations longer and more difficult. Finally, inertial phenomena cannot be neglected because of the relatively high displacement speeds that can occur in silos.
