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PROCEEDINGS OF THE FIFTEENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: J. Kruis, Y. Tsompanakis and B.H.V. Topping
Coupling Cracking and Permeability to Assess the Leakage Rate of Concrete Structures
F. Dufour, M.E. El Dandachy, M. Briffaut and S. dal Pont
University Grenoble Alpes and CNRS, Grenoble, France
F. Dufour, M.E. El Dandachy, M. Briffaut, S. dal Pont, "Coupling Cracking and Permeability to Assess the Leakage Rate of Concrete Structures", in J. Kruis, Y. Tsompanakis, B.H.V. Topping, (Editors), "Proceedings of the Fifteenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 22, 2015. doi:10.4203/ccp.108.22
Keywords: cracking, damage, leakage, structural permeability, experiments, modelling, finite element.
Both the durability analysis of concrete structures submitted to an aggressive environment and the serviceability analysis of concrete structures with a tightness role (for instance, gas reservoirs or confinement vessels for nuclear power plants) necessitate the development of the modelling of transfer properties linked to the mechanical state of the material.
To this end, an original experimental research programme was conducted on a concrete disk loaded in a splitting test. During the loading, a gas permeability analysis is performed. This test is further used as a benchmark test to qualify the performance of two numerical approaches.
Since one is mostly interested in the evolution of structural permeability due to cracking, the first issue is to model both the crack initiation and propagation accurate enough. In this paper a stress based non local damage model is chosen for its capacity to model both crack initiation and propagation. The comparison with the experimental mechanical response is very good.
From the damage field, there are two ways to assess leakage rate. The most straightforward is to use a coupling relationship between damage and permeability at the material scale. The damage field directly provides a permeability field used for a diffusion problem based on Darcy's law. The second approach is to estimate the crack properties from the damage continuum model. The flow rate is estimated along the crack path, using the modified Poiseuille's law.
Both approaches are compared with the experimental results showing that the continuous approach is more suited to model the initial permeability increases during microcracking whereas the discrete approach performs much better at failure and along unloading branches.
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