Un modèle rhéologique pour les argiles gonflantes

Abstract

After remembering the physico-chemical mechanism of saturated clay in isothermal conditions, we propose an elastoplastic model for expansive clays. The formulation considers in normally consolidated states, an irreversible strain of micro structure due to macro-pores compaction. The irreversible macroscopic strains result from the deformation of micro structures are described with associative plastic law. In the overconsolidated states, the repulsive stresses provoke an irreversible dilatancy of macro-pores. The macroscopic swelling of the last phenomenon is formulated by the second plastic mechanism with the combined isotropic and kinematics hardening. The rheological model schematises the normally consolidated states by mechanical hardening and the over consolidated states by « physico-chemical » hardening. The model is able to describe the fundamental characteristic of saturated expansive clays, especially the hysteresis loop in odometer tests and the existence of the volume change in triaxial tests at over-consolidated states. The model needs eight parameters that must be identified by means of the odometer and triaxial tests. Finally, this paper shows the predictions of model for the different tests with the experiments performed on Boom clay. The comparison between experimental results and model confirm the behaviour of the expensive clays.

Clay Mineral Type and Content Control Properties of Fine-Grained CO2 Caprocks—Laboratory Insights from Strongly Swelling and Non-Swelling Clay–Quartz Mixtures

“…As Figure 7 demonstrates, the majority of published kaolinite compaction curves document 17-25% total porosity at 50 MPa effective vertical stress [23,26,[55][56][57][58][59][60][61][62][63]. The coarser kaolinite grains were more susceptible to compaction (more compressible) than the finer kaolinites.…”