An elastoplastic model of bentonite free swelling

• We propose a new elastoplastic mechanism to model bentonite free swelling.
• Plastic strains induced by microstructural effects are activated by free swelling.
• A new approach to the calculation of the microstructural void ratio is introduced.
• It is advisable to use a kinetic micro-macrostructural water exchange term.
• The proposed formulation yields satisfactory results for the analysed tests.

This article proposes a new plastification mechanism to model bentonite free swelling processes by using an elastoplastic approach. The formulation is based on an interaction function that defines the plastic macrostructural strains induced by microstructural effects. This term is defined as a function of the microstructural void ratio, and it establishes a direct connection between the destructuration of the micro- and macrostructures of the bentonite during the free swelling processes. The formulation proposed also includes a new approach to the calculation of the microstructural void ratio as well as a new method to describe the kinetic mass exchange between micro- and macrostructural water, considering that there may not be equilibrium between the two types of water. The model was used to analyse several free swelling tests and was found to yield satisfactory results.