A damage-plasticity model for cohesive fractures

• The effects of damage process in rock joints behavior and rock slope instability are underlined.
• A model combining plastic deformation and damage process in rock joints and cohesive cracks is proposed.
• It is shown that the model reproduces well the main features of elastic-plastic and damage behavior of cohesive fractures.
• The model has been validated by comparison to several sets of experimental data.

A model for the elastic-plastic deformation and damage process in rock joints and interfaces in quasi-brittle geomaterials is proposed. A close analysis of damage process in interfaces in quasi-brittle geomaterials, represented in cohesive crack models, shows that these models represent well also the damage process in rock joints. The commonly used non-linear elastic-plastic models of rock joints are completed by this damage process and extended to a general model for cohesive fractures which cover rock joints and cohesive cracks. This model reproduces well the main aspects of deformation and damage of cohesive fractures observed experimentally, namely, a non-linear elastic behavior before the stress peak, softening and decrease of the tensile and shear strengths with post-peak deformation, stiffness reduction after stress peak, general trends of irreversible relative displacements and existence of a residual stiffness in ultimate state under compression and shear. This model was fitted to several series of experimental results obtained on different geomaterials and a satisfying agreement between the model and experimental data was obtained.