A cohesive damage–friction interface model accounting for water pressure on crack propagation

Aim of the work is the study of crack propagation in concrete constructions, such as dams, taking into account the water pressure effects and the damage–friction evolution with unilateral contact. With this aim, an interface model, based on the cohesive fracture, is developed. In particular, a damage–friction model based on a new multiscale approach is proposed for the interface, which is able to simulate crack propagation in mode I, mode II, and mixed mode. The criteria for crack initiation and propagation and the closure and reopening of the crack are considered for the interface. The friction and the dilatancy are characterized by a decreasing rate of friction and dilatancy angles, respectively, with the possibility of the dilatancy recovering during cyclic loading. The water pressure effect is taken into account by considering a further static pressure acting on the real crack and in the process zone. The value of this pressure is set as a function of the crack opening displacement and it varies from a prescribed initial pressure to the external water pressure. A numerical procedure is developed in order to integrate the evolutive laws governing the interface model. The interface model is implemented in finite element codes; some numerical simulations and a comparison with experimental data are performed in order to validate the proposed model and to investigate the influence of the water pressure effects on the crack propagation. Finally, the mechanical response of a concrete dam is studied.