Modeling the behavior of compacted bentonites under low porosity conditions

This article proposes an approach to ensure consistency between constitutive formulations used in double-porosity models when the macrostructural void ratio, e_M, is very small. These formulations model processes of different physical natures and therefore are usually presented independently, in which case an additive decomposition is assumed, and they calculate the total strain of the system as the sum of the strains caused by each process. This independence means that when e_M is reduced, the contributions considered are not always consistent. To solve this problem, soil stiffness in the proposed approach is increased when e_M is reduced, and at the same time the effect on strain by macrostructural processes not linked to changes in stress is reduced. To simulate the flow, it is assumed that there is always a minimum operating value of e_M that controls mass transport. This approach was applied to a practical case, and confirmed that when the effect of the stress state on microstructure behavior was taken into account, the conceptual framework initially proposed for non-negligible e_M values was satisfactorily extended.