It is well known that frictional materials, as for instance granular solid materials like soil or concrete, exhibit a strong tendency towards localization. When localization occurs deformations concentrate in small bands of finite width, so-called shear bands. Concerning the numerical treatment of these phenomena, e. g. in the framework of the finite element method, it is well known that one obtains an ill-posed problem, where both the direction of the shear band and the shear band width itself strongly depend on the discretization, especially, on the mesh size and orientation. To overcome this unphysical behaviour, different regularization strategies have been applied. In the present contribution two natural regularization mechanisms for porous materials are concerned, namely, (1) the introduction of micropolar rotations of the skeleton grains in the sense of the Cosserat brothers and (2) the inclusion of the pore-fluid viscosity in the saturated case.     «

It is well known that frictional materials, as for instance granular solid materials like soil or concrete, exhibit a strong tendency towards localization. When localization occurs deformations concentrate in small bands of finite width, so-called shear bands. Concerning the numerical treatment of these phenomena, e. g. in the framework of the finite element method, it is well known that one obtains an ill-posed problem, where both the direction of the shear band and the shear band width itself...     »