Pub Date : 2007-08-01DOI: 10.1080/17747120.2007.9692970
D. Kondo, H. Welemane, F. Cormery
ABSTRACT In this paper, we present some basic elements of macroscopic modelling of damage. We then recall the general approach of continuum damage based on the thermodynamics of irreversible processes and its application to isotropic damage modelling. The study of damage-induced anisotropy is treated by considering a second order tensorial damage variable. Finally, we present an original macroscopic approach through which is addressed the question of unilateral effects due to the microcracks closure.
{"title":"Basic concepts and models in continuum damage mechanics","authors":"D. Kondo, H. Welemane, F. Cormery","doi":"10.1080/17747120.2007.9692970","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692970","url":null,"abstract":"ABSTRACT In this paper, we present some basic elements of macroscopic modelling of damage. We then recall the general approach of continuum damage based on the thermodynamics of irreversible processes and its application to isotropic damage modelling. The study of damage-induced anisotropy is treated by considering a second order tensorial damage variable. Finally, we present an original macroscopic approach through which is addressed the question of unilateral effects due to the microcracks closure.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116512220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-08-01DOI: 10.1080/17747120.2007.9692971
L. Dormieux, D. Kondo
ABSTRACT This paper proposes a brief overview of the micromechanics approach to the modelling of crack-induced damage. To begin with, the main lines of the micromechanics reasoning are presented and applied to cracked media. We then introduce the so-called dilute and Mori-Tanaka homogenization schemes which are herein implemented in the context of a solid matrix weakened by opened or closed cracks. The above modelling is extended to the situation of fluid-filled cracks, yielding a micromechanics theory of poroelastic damage. Finally, the combination of the previous findings with a standard thermodynamics argument allows to deal with the essential question of damage evolution which is regarded here as the consequence of cracks propagation.
{"title":"Micromechanics of damage propagation in fluid-saturated cracked media","authors":"L. Dormieux, D. Kondo","doi":"10.1080/17747120.2007.9692971","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692971","url":null,"abstract":"ABSTRACT This paper proposes a brief overview of the micromechanics approach to the modelling of crack-induced damage. To begin with, the main lines of the micromechanics reasoning are presented and applied to cracked media. We then introduce the so-called dilute and Mori-Tanaka homogenization schemes which are herein implemented in the context of a solid matrix weakened by opened or closed cracks. The above modelling is extended to the situation of fluid-filled cracks, yielding a micromechanics theory of poroelastic damage. Finally, the combination of the previous findings with a standard thermodynamics argument allows to deal with the essential question of damage evolution which is regarded here as the consequence of cracks propagation.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134600454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-08-01DOI: 10.1080/17747120.2007.9692977
A. Simone
ABSTRACT This paper illustrates the advantages of a continuous-discontinuous failure description. Examples using standard strain-hardening plasticity, strain-softening gradient-enhanced damage and viscoplastic damage show that a better approximation of failure processes can be achieved by using numerical techniques in which a discontinuity is naturally endowed in the model itself and is activated at some stage during localization (by using a cohesive discontinuity) or after the localization process has been completed (by using a traction-free discontinuity). Failure can then be realistically described as progressive material degradation which develops into a discrete crack for which a discontinuity in the displacement field is a suitable representation.
{"title":"Continuous-discontinuous modeling of failure","authors":"A. Simone","doi":"10.1080/17747120.2007.9692977","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692977","url":null,"abstract":"ABSTRACT This paper illustrates the advantages of a continuous-discontinuous failure description. Examples using standard strain-hardening plasticity, strain-softening gradient-enhanced damage and viscoplastic damage show that a better approximation of failure processes can be achieved by using numerical techniques in which a discontinuity is naturally endowed in the model itself and is activated at some stage during localization (by using a cohesive discontinuity) or after the localization process has been completed (by using a traction-free discontinuity). Failure can then be realistically described as progressive material degradation which develops into a discrete crack for which a discontinuity in the displacement field is a suitable representation.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131222356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692953
L. Dormieux
ABSTRACT Homogenization has been widely used in order to provide a micromechanics interpretation of the phenomenological transport laws in porous media. We herein first recall some basic features of the double scale expansion technique in periodic media, successively applied to the derivation of Darcy's law and the modelling of the coupling between advection and diffusion. We then focus on the permeability of a disordered cracked material. Using the concept of equivalent permeability for a flat plane crack, the implementation of a self-consistent homogenization scheme allows to determine a percolation threshold of the crack network.
{"title":"Application des méthodes d'homogénéisation au transport dans les milieux poreux","authors":"L. Dormieux","doi":"10.1080/17747120.2007.9692953","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692953","url":null,"abstract":"ABSTRACT Homogenization has been widely used in order to provide a micromechanics interpretation of the phenomenological transport laws in porous media. We herein first recall some basic features of the double scale expansion technique in periodic media, successively applied to the derivation of Darcy's law and the modelling of the coupling between advection and diffusion. We then focus on the permeability of a disordered cracked material. Using the concept of equivalent permeability for a flat plane crack, the implementation of a self-consistent homogenization scheme allows to determine a percolation threshold of the crack network.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129860281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692952
P. Lebon
ABSTRACT To prevent the dissemination of radionuclides at different timescales, a deep geological repository is assigned a number of safety functions, which complement each other to optimise the system's overall performance. Transfer properties have been studied for each confinment barriers in agreement with the environmental context of a disposal. Measurement methodologies have to cope with very low permeabilities and diffusivities. Uncertainties on the data have been dramatically reduced. R&D axes aim at understanding processes at a microscopic scale to better assess how they are modified with time and how the different barriers interact with each others.
{"title":"Propriétés de transfert des géomatériaux pour le stockage des déchets radioactifs en formation géologique","authors":"P. Lebon","doi":"10.1080/17747120.2007.9692952","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692952","url":null,"abstract":"ABSTRACT To prevent the dissemination of radionuclides at different timescales, a deep geological repository is assigned a number of safety functions, which complement each other to optimise the system's overall performance. Transfer properties have been studied for each confinment barriers in agreement with the environmental context of a disposal. Measurement methodologies have to cope with very low permeabilities and diffusivities. Uncertainties on the data have been dramatically reduced. R&D axes aim at understanding processes at a microscopic scale to better assess how they are modified with time and how the different barriers interact with each others.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123204028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692958
A. Aït-Mokhtar, O. Millet, O. Amiri
ABSTRACT A macroscopic modelling of the chloride transport through saturated cement-based materials is carried out by using the periodic homogenization technique. The dimensional analysis of Nernst-Planck equation leads to dimensionless parameters characterizing the problem. Given the electrical field applied in the experimental validation, the asymptotic expansion of Nernst-Planck equation leads to a macroscopic model only involving migration. From this analysis, a classical experimental procedure allows obtaining the homogenized diffusion coefficient.
{"title":"Electrodiffusion in porous media","authors":"A. Aït-Mokhtar, O. Millet, O. Amiri","doi":"10.1080/17747120.2007.9692958","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692958","url":null,"abstract":"ABSTRACT A macroscopic modelling of the chloride transport through saturated cement-based materials is carried out by using the periodic homogenization technique. The dimensional analysis of Nernst-Planck equation leads to dimensionless parameters characterizing the problem. Given the electrical field applied in the experimental validation, the asymptotic expansion of Nernst-Planck equation leads to a macroscopic model only involving migration. From this analysis, a classical experimental procedure allows obtaining the homogenized diffusion coefficient.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121180692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692964
L. Stefan, F. Benboudjema, F. Robert, Micheline Moranville
ABSTRACT In this paper, we present a study on the drying of cement-based materials. Monitoring the weight loss of a concrete specimen in a controlled relative humidity room could be a way to determine the water permeability of concrete. However, we show that this method depends in a great extent to the used models. Two models for the desorption isotherm are used in order to show that the choice of the model has a great impact on the identified water permeability. Moreover, numerical simulations taking into account damage are performed in order to understand the effect of cracking on the identified water permeability.
{"title":"Séchage et retrait","authors":"L. Stefan, F. Benboudjema, F. Robert, Micheline Moranville","doi":"10.1080/17747120.2007.9692964","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692964","url":null,"abstract":"ABSTRACT In this paper, we present a study on the drying of cement-based materials. Monitoring the weight loss of a concrete specimen in a controlled relative humidity room could be a way to determine the water permeability of concrete. However, we show that this method depends in a great extent to the used models. Two models for the desorption isotherm are used in order to show that the choice of the model has a great impact on the identified water permeability. Moreover, numerical simulations taking into account damage are performed in order to understand the effect of cracking on the identified water permeability.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123887944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692963
Marta Choinska, Abdelhafid Khelidj, F. Dufour, G. Pijaudier-Cabot
ABSTRACT The objective of this study is to investigate damage-temperature-permeability interactions in structural concrete. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading and temperature up to 150°C. The results emphasize that at stress levels lower than 80–85% of the peak stress, the variation of permeability is small and it is slightly influenced by the stress. As the load exceeds 80–85% of the peak stress and approaches the peak, microcracking increases rapidly, causing an important increase of the permeability. In the post-peak phase the increase of permeability is much larger due to significant macrocrack width growth. The increase of permeability with the applied mechanical load seems to be greater with temperature, inducing the further alteration of concrete and dilation of the porous structure of the material. Finally, the obtained results reveal that the effects of damage and temperature may be decoupled for the estimation of the concrete permeability.
{"title":"Etude expérimentale de l'interaction endommagement-température-état de contrainte-perméabilité du béton","authors":"Marta Choinska, Abdelhafid Khelidj, F. Dufour, G. Pijaudier-Cabot","doi":"10.1080/17747120.2007.9692963","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692963","url":null,"abstract":"ABSTRACT The objective of this study is to investigate damage-temperature-permeability interactions in structural concrete. The tests are performed on hollow cylindrical concrete specimens, subjected to compressive loading and temperature up to 150°C. The results emphasize that at stress levels lower than 80–85% of the peak stress, the variation of permeability is small and it is slightly influenced by the stress. As the load exceeds 80–85% of the peak stress and approaches the peak, microcracking increases rapidly, causing an important increase of the permeability. In the post-peak phase the increase of permeability is much larger due to significant macrocrack width growth. The increase of permeability with the applied mechanical load seems to be greater with temperature, inducing the further alteration of concrete and dilation of the porous structure of the material. Finally, the obtained results reveal that the effects of damage and temperature may be decoupled for the estimation of the concrete permeability.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126294864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692959
Christophe Baux, Y. Mélinge, C. Lanos, Khanh-Son Nguyen
ABSTRACT High temperature thermal transfer in hydrated minerals (such as gypsum, cement…) is studied and modelled. Exposed to fire, the studied materials are subject to phases transitions correlated with a high dehydration latent heat. The development of an electric furnace allowing the realisation of unidirectional high thermal transfer. The results of these trials are collected and merge in a database of experimental results. Concurrently, a thermal transfer model is built. Thermal analyses such as DTA/TG are used to determine the degradation kinetics of hydrated minerals. The degradation kinetics is modelled with a classical solid state kinetic law based on the chemical reaction rate. This law is used to balance the dehydration latent heat introduced in the heat equation. The developed model is then based on an implicit scheme and uses the finite difference method. Modelled and experimental results are presented herein.
{"title":"Modélisation du comportement thermique haute température de matériaux minéraux","authors":"Christophe Baux, Y. Mélinge, C. Lanos, Khanh-Son Nguyen","doi":"10.1080/17747120.2007.9692959","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692959","url":null,"abstract":"ABSTRACT High temperature thermal transfer in hydrated minerals (such as gypsum, cement…) is studied and modelled. Exposed to fire, the studied materials are subject to phases transitions correlated with a high dehydration latent heat. The development of an electric furnace allowing the realisation of unidirectional high thermal transfer. The results of these trials are collected and merge in a database of experimental results. Concurrently, a thermal transfer model is built. Thermal analyses such as DTA/TG are used to determine the degradation kinetics of hydrated minerals. The degradation kinetics is modelled with a classical solid state kinetic law based on the chemical reaction rate. This law is used to balance the dehydration latent heat introduced in the heat equation. The developed model is then based on an implicit scheme and uses the finite difference method. Modelled and experimental results are presented herein.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116790389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-06-01DOI: 10.1080/17747120.2007.9692960
J. Sercombe, R. Vidal, C. Galle, F. Adenot
ABSTRACT This paper presents an experimental study of gas diffusion through cement pastes (CEM I and CEM V). First, the impact of Relative Humidity (RH) on gas diffusion is investigated by performing tests on samples pre-conditioned in specific atmospheric conditions (dry, 55%, 70%, 82%, 93% and 100% RH) by means of saline solutions. The results obtained with hydrogen show the important evolution of gas diffusion coefficients with the water saturation. Second, diffusion tests at different total pressures and with different gas mixtures (hydrogen—nitrogen and xenon—nitrogen) are performed to study the nature of gas diffusion in cementitious materials. Results demonstrate that gas diffusion in the tested cement pastes is controlled by Knudsen diffusion rather than by ordinary diffusion.
{"title":"Diffusion des gaz dans les ciments","authors":"J. Sercombe, R. Vidal, C. Galle, F. Adenot","doi":"10.1080/17747120.2007.9692960","DOIUrl":"https://doi.org/10.1080/17747120.2007.9692960","url":null,"abstract":"ABSTRACT This paper presents an experimental study of gas diffusion through cement pastes (CEM I and CEM V). First, the impact of Relative Humidity (RH) on gas diffusion is investigated by performing tests on samples pre-conditioned in specific atmospheric conditions (dry, 55%, 70%, 82%, 93% and 100% RH) by means of saline solutions. The results obtained with hydrogen show the important evolution of gas diffusion coefficients with the water saturation. Second, diffusion tests at different total pressures and with different gas mixtures (hydrogen—nitrogen and xenon—nitrogen) are performed to study the nature of gas diffusion in cementitious materials. Results demonstrate that gas diffusion in the tested cement pastes is controlled by Knudsen diffusion rather than by ordinary diffusion.","PeriodicalId":368904,"journal":{"name":"Revue Européenne de Génie Civil","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121209092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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