Modèle d'endommagement avec refermeture de la porosité pour le calcul des ouvrages souterrains

A damage model is proposed to model ground loss of confinement around an underground excavation and apply it to the convergence-confinement method. The constitutive law is based, on the one hand on a continuous evolution of a damage scalar variable and, on the other hand, on a progressive closure of porosity with the volumetric deformation. This law makes it possible to directly couple the stiffness with the hydrostatic pressure around the cavity in dry grounds, as often observed in situ. Identification of parameters is carried out by the means of triaxial tests. An application with the convergence-confinenment method hypothesis is finally proposed for a deep tunnel bored in sandstone.