DAMAGE MODEL FOR FAILURE ANALYSIS WITH A VIEW TO HYDROMECHANICAL PROBLEMS

In some cases, the evaluation of the leaking rate through a concrete structure is a crucial step. For nuclear power plants for example, the hydraulic integrity of the containment building is a point of concern for energy producers like EDF in France. The sealing of the barrier between the inner nuclear part and the outer environmental one has indeed to be ensured even in cases of strong accidents. To estimate the durability of the structure in time (ageing process), the effect of a mechanical load on the transport properties, and especially on the hydraulic conductivity, has thus to be investigated. The main question is to quantify the evolution of the permeability with load and to determine which mechanical properties affect it. From a combined mechanical – hydraulic discrete approach, based on lattice models, it is shown how, for pre – peak situations, the value of the damage is the most appropriate variable to quantify the evolution of permeability. It also proves, for unloaded specimens, the independence of the law on the material properties of concrete, proposing a theoretical explanation to some former experimental observations (Picandet et al. [1]). From this study, the description of the damage evolution during loading becomes a crucial point.