Finite element simulation of consolidation processes and bentonite swelling in the framework of unsaturated porous media

摘要

Clays and bentonites receive increasing attention as technical buffer materials in geological and engineered barriers in order to isolate waste. The analysis of these systems requires a correct understanding of the material behavior and an appropriate numerical technique as well. A coupled hydro-mechanical finite element strategy is presented where the problem is formulated in the context of unsaturated porous media considering a gaseous, a liquid and a solid phase. For the fluid flow the permeability-saturation function by van Genuchten is assumed. The constitutive equation for the bentonite swelling is based on experiments. We use the material model by Studer et al. and Boergesson et al. for swelling effects which gives a dependency of saturation, moisture swelling and resulting permeability changes. In our code RockFlow/RockMech this moisture swelling model and a coupled hydro-mechanical strategy are implemented in order to simulate saturation dependent deformations influencing the stress and the flow field as well. The results of the hydro-mechanical modelling are compared with experiments by Liakopoulos and data from the VEGAS-GMT experiment.