An elasto-plastic damage model for argillaceous geomaterials

The aim of this paper is to present a new elastoplastic damage model for unsaturated porous media. The proposed model within the context of poromechanics is intended for constitutive modelling of geomaterials which show two (irreversible) dissipative aspects involving plastic flow and damage. Independent stress state variables, namely net stress and suction, are adopted as stress variables of the model. Barcelona Basic Model is extended to a non-isothermal formulation and is coupled to a damage formulation using damage dependent yield surface and damaged stress variables. The stress state variables are transformed into the damaged state through the definition of effective damaged suction and effective damaged net stress in the framework of Continuum Damage Mechanics (CDM). Damage effects on intrinsic permeability and transfer laws are also taken into consideration. The model has been implemented in Θ-STOCK Code and predictive capabilities of the model have been evaluated against experimental results from the literature. The model is validated by comparing the numerical results with experimental results of argillites and results of an elastodamage model. The proposed model is also shown to give satisfactory simulation results which match the experimental data from a heating test on bentonite samples.