A thermodynamically consistent framework for saturated viscoplastic rock-materials subject to damage

The aim of this study is to build a thermodynamically consistent theoretical framework to model viscoplasticity and damage in saturated geomaterials. The induced anisotropic damage is represented by a second-order tensor. The key point of the model formulation is the definition of a “double effective stress”, stemming from the concept of “damaged effective stress” (used in Continuum Damage Mechanics to couple damage and viscoplasticity in solids), and from the concept of “hydro-mechanical effective stress” (used in poromechanics to account for solid–fluid interactions). The dissipation potential is expressed as a function of the “double effective stress”, which makes it possible to couple creep, fluid flow and damage in a consistent framework.