Investigating the hydromechanical behaviour of bentonite pellets by swelling pressure tests and discrete element modelling

Benjamin Darde (1) , Jean-Noël Roux (1) , Jean-Michel Pereira (1) , Patrick Dangla (1) , Jean Talandier (2) , Minh Ngoc Vu (2) , Anh Minh A.M. Tang (1)

1 NAVIER UMR 8205 - Laboratoire Navier
2 ANDRA - Agence Nationale pour la Gestion des Déchets Radioactifs

Bentonite pellet mixtures are candidate material for the sealing of galleries in radioactive waste disposals. The hydromechanical behaviour of assemblies of bentonite pellets is investigated upon partial hydration through (1) suction-controlled swelling pressure tests in the laboratory and (2) discrete element method simulations. The combination of these experimental and numerical approaches highlights that, before the mixture homogenization, the swelling pressure develops in two phases. The first phase is characterized by an increase in contact forces between pellets. The second phase is characterized by plasticity at contacts between pellets and is controlled by the progressive decrease in pellet strength and stiffness upon hydration. In addition, numerical results highlight that the swelling pressure measured in the laboratory can be influenced by the sample preparation, the cell size, and the diameter of the pressure sensor.

Mots clés: Expansive soils; Pellets; Swelling pressure; DEM simulations

Domaines: Sciences de l'ingénieur [physics]; Génie civil; Géotechnique

Benjamin Darde, Jean-Noël Roux, Jean-Michel Pereira, Patrick Dangla, Jean Talandier, et al.. Investigating the hydromechanical behaviour of bentonite pellets by swelling pressure tests and discrete element modelling. Acta Geotechnica, 2021, 16 (2), pp.507-524. ⟨10.1007/s11440-020-01040-5⟩. ⟨hal-03053589⟩