SUMMARYThe formulation of the poroelastoplastic constitutive equations at large strains of a fully saturated material is performed focusing on the usually ignored influence of large strain plasticity on the poroelastic properties. A micromechanics approach allows to take into account the evolution of the microstructure geometry which in turn induces a coupling between elasticity and plasticity. Such a coupling results in an additional term in the macroscopic Cauchy stress rate equation derived from inclusion-based estimates that leads to a modified Jaumann derivative. The pressure rate equation is also analysed. The finite element discretization of finite poroplasticity is then presented taking into account the elasticity-plasticity coupling. Application to the consolidation situation shows that the coupling may lead to non-negligible effects.

SUMMARYThe paper deals with the modeling of some aspects, such as the formulation of constitutive equations for sediment material or finite element approach for basin analysis, related to mechanical compaction in sedimentary basins. In addition to compaction due to gravity forces and pore-pressure dissipation, particular emphasis is given to the study of deformation induced by tectonic sequences. The numerical model relies upon the implementation of a comprehensive constitutive model for the sediment material formulated within the framework of finite poroplasticity. The theoretical model accounts for both hydromechanical and elasticityplasticity coupling due to the effects of irreversible large strains. From the numerical viewpoint, a finite element procedure specifically devised for dealing with sedimentary basins as open systems allows to simulate within a two-dimensional setting the process of sediment accretion or erosion.Several basin simulations are presented.The main objective is to analyze the behavior of a sedimentary basin during the different phases of its life cycle: accretion phase, pore-pressure dissipation phase and compressive/extensional tectonic motions.

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