On localization in saturated porous continua

Localization in elastic-plastic saturated porous media is investigated here using a linear perturbation approach. The adopted localization criterion corresponds to unbounded growth of perturbations. The critical conditions are compared with those obtained by a classical band analysis. While for one phase materials these conditions coincide, in the present context the linear perturbation approach leads in the limit of unbounded growth to the singularity of the undrained acoustic tensor, while the band analysis leads to the singularity of the drained acoustic tensor. Some general results clarifying the hierarchy of these two conditions are established for a guile general set of constitutive equations. (C) 2000 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.