Model of water transfer in concrete and rock based on a single state variable to consider simultaneous positive pressure and drying boundary conditions

During their service life, concrete structures may be subjected to positive pressure and drying boundary conditions simultaneously. This phenomenon is likely to occur in civil engineering structures, such as tunnels for nuclear waste storage, dams, and piles, where the simultaneous phenomena of drying and saturation must be considered because of their strong effects on the short-and long-term behavior of the structure. The water transport model proposed in this paper predicts the mass transfer and water field in the material. It provides a continuous description of saturated and unsaturated media using liquid pressure as the only state variable and also considers the effects of temperature variations. A formulation for water transfer with a single state variable is presented, followed by an illustration of its numerical implementation and a procedure for the calibration of parameters. The model is compared with experimental and numerical results to validate its efficiency. For this purpose, several applications dealing with drying and saturation phenomena are used. The results obtained show the potential of the proposed water transfer model to evaluate the water transport in the material under study at different temperatures by simulating a mock-up of nuclear power plant wall. It is finally used to predict the re-saturation of an underground nuclear waste disposal structure.