Some constitutive and computational aspects of coupled hydraulic-damage problems for leakage rate predictions of concrete vessels

摘要

This contribution presents a review of the works carried out at R&DO in Nantes, in collaboration with Electricite de France. The aim is the study of sensitive structures like containment vessels of nuclear power plants, and the evaluation of their gas tightness more specifically. The objective is the computation of the leakage rate of vessels subjected to internal pressure (typically during integrity tests). It requires the evaluation of the material permeability, as a function of the moisture content in concrete and of the amount of damage. We focus mainly on the relationship between gas permeability and material damage, starting from an elastic-plastic-damage constitutive relation and analyzing the relationship with the permeability with the help of a discrete (lattice) analysis. The global solution strategy relies on chained calculations, as for large size structures, fully coupled problems remains out of reach. An example on a representative structural element is provided. This review concludes on some size effect analysis of damaged specimens, which shows that both approaches to cracking - discrete and continuous - exhibit the same effect of size on transfer properties of structural elements.