Documents disponibles écrits par cet auteur

Deformation and cracking of seepage barriers in dams due to changes in the pore pressure regime / John D. Rice in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 16-25 Titre : Deformation and cracking of seepage barriers in dams due to changes in the pore pressure regime Type de document : texte imprimé Auteurs : John D. Rice, Auteur ; J. Michael Duncan, Auteur Article en page(s) : pp. 16-25 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Seepage  barrier  Cutoff  Seepage  Deformation  Dam  Finite  element Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A procedure is presented for analyzing postconstruction deformation of seepage barriers due to changes in the pore pressure regime after seepage barrier construction. The procedure uses the changes in pore pressures calculated by finite-element seepage analyses to calculate changes in buoyancy and seepage forces that occur as a result of seepage barrier construction. When the buoyancy and seepage forces are applied to a finite-element soil-structure interaction model, the result is an effective-stress analysis that rigorously models seepage effects. This paper discusses application of the procedure to five dams to calculate postconstruction deformation and stresses in seepage barriers. The results of the analyses indicate that deformation due to pore pressure regime changes is a likely mechanism causing cracking in rigid seepage barriers. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Deformation and cracking of seepage barriers in dams due to changes in the pore pressure regime [texte imprimé] / John D. Rice, Auteur ; J. Michael Duncan, Auteur . - pp. 16-25. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 16-25 Mots-clés : Seepage  barrier  Cutoff  Seepage  Deformation  Dam  Finite  element Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : A procedure is presented for analyzing postconstruction deformation of seepage barriers due to changes in the pore pressure regime after seepage barrier construction. The procedure uses the changes in pore pressures calculated by finite-element seepage analyses to calculate changes in buoyancy and seepage forces that occur as a result of seepage barrier construction. When the buoyancy and seepage forces are applied to a finite-element soil-structure interaction model, the result is an effective-stress analysis that rigorously models seepage effects. This paper discusses application of the procedure to five dams to calculate postconstruction deformation and stresses in seepage barriers. The results of the analyses indicate that deformation due to pore pressure regime changes is a likely mechanism causing cracking in rigid seepage barriers. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]

Findings of case histories on the long-term performance of seepage barriers in dams / John D. Rice in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 2-15 Titre : Findings of case histories on the long-term performance of seepage barriers in dams Type de document : texte imprimé Auteurs : John D. Rice, Auteur ; J. Michael Duncan, Auteur Article en page(s) : pp. 2-15 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Seepage  barrier  Cutoff  wall  Seepage  Case  history  Long-term  performance Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In a vast majority of cases, seepage barriers increase the reliability of dams. However, it is important to recognize that seepage barriers often drastically increase hydraulic gradients around the boundaries of the barrier, and through any windows or defects in the barrier. The result is increased water pressures and hydraulic gradients behind and around the barrier. These increased pressures and gradients have potential to provide the catalyst for initiation of several modes of internal erosion that were either unlikely or less likely without the seepage barrier. As a consequence, seepage barriers give rise to the potential for additional mechanisms of internal erosion and piping in the dam and the foundation. A compendium of 30 case histories of dams that have had seepage barriers in place for over 10 years has been assembled, and observations and insights garnered from these case studies were compiled. Finite-element seepage and deformation analyses have been performed to provide better understanding of the performance of seepage barriers and the mechanisms that affect their performance. This paper presents a summary of our findings from the case histories and the analyses performed. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Findings of case histories on the long-term performance of seepage barriers in dams [texte imprimé] / John D. Rice, Auteur ; J. Michael Duncan, Auteur . - pp. 2-15. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 2-15 Mots-clés : Seepage  barrier  Cutoff  wall  Seepage  Case  history  Long-term  performance Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : In a vast majority of cases, seepage barriers increase the reliability of dams. However, it is important to recognize that seepage barriers often drastically increase hydraulic gradients around the boundaries of the barrier, and through any windows or defects in the barrier. The result is increased water pressures and hydraulic gradients behind and around the barrier. These increased pressures and gradients have potential to provide the catalyst for initiation of several modes of internal erosion that were either unlikely or less likely without the seepage barrier. As a consequence, seepage barriers give rise to the potential for additional mechanisms of internal erosion and piping in the dam and the foundation. A compendium of 30 case histories of dams that have had seepage barriers in place for over 10 years has been assembled, and observations and insights garnered from these case studies were compiled. Finite-element seepage and deformation analyses have been performed to provide better understanding of the performance of seepage barriers and the mechanisms that affect their performance. This paper presents a summary of our findings from the case histories and the analyses performed. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]

Reliability-based underseepage analysis in levees using a response surface–monte carlo simulation method / John D. Rice in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 7 (Juillet 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 821–830 Titre : Reliability-based underseepage analysis in levees using a response surface–monte carlo simulation method Type de document : texte imprimé Auteurs : John D. Rice, Auteur ; Lourdes Polanco, Auteur Année de publication : 2012 Article en page(s) : pp. 821–830 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Levee  Seepage  Reliability  Piping  Heave Résumé : Present methods for assessing the potential for unsatisfactory levee performance because of underseepage consist of deterministic seepage analyses and simplified reliability methods. Deterministic methods consist of calculating factors of safety based on the ratio of the critical gradients of the soil and hydraulic exit gradients without taking into account high levels of uncertainty in soil properties and subsurface geometry that are inherent to many levee analyses. The most common simplified reliability approaches currently being used to analyze levees against underseepage apply the first-order second-moment Taylor series method, using the U.S. Army Corps of Engineers blanket theory equations as the performance functions. In many cases, these methods do not realistically reflect the geometry of the levee’s foundation soils and the uncertainty associated with their performance. This study proposes a new application for the response surface method that allows modeling the initiation of erosion process with more accurate failure mechanisms and more complex subsurface geometry. The response surface–Monte Carlo (RSMC) simulation method uses finite-element analyses to develop a series of equations that define the relationship between the variables and the factor of safety (F). Using these equations, probability density functions (PDF) for variables, and the computer program @Risk, a Monte Carlo simulation is performed to calculate the conditional probability of unsatisfactory performance because of underseepage for a given river flood level. Two examples are presented to illustrate the proposed procedure. Multiple regression analyses are performed to assess the relative effect that changes in the input variables have on the F for the various analyses. The results suggest that uncertainty in the levee geometry has the greatest effect on the variation of the F for the cases studied. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000650 [article] Reliability-based underseepage analysis in levees using a response surface–monte carlo simulation method [texte imprimé] / John D. Rice, Auteur ; Lourdes Polanco, Auteur . - 2012 . - pp. 821–830. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 7 (Juillet 2012) . - pp. 821–830 Mots-clés : Levee  Seepage  Reliability  Piping  Heave Résumé : Present methods for assessing the potential for unsatisfactory levee performance because of underseepage consist of deterministic seepage analyses and simplified reliability methods. Deterministic methods consist of calculating factors of safety based on the ratio of the critical gradients of the soil and hydraulic exit gradients without taking into account high levels of uncertainty in soil properties and subsurface geometry that are inherent to many levee analyses. The most common simplified reliability approaches currently being used to analyze levees against underseepage apply the first-order second-moment Taylor series method, using the U.S. Army Corps of Engineers blanket theory equations as the performance functions. In many cases, these methods do not realistically reflect the geometry of the levee’s foundation soils and the uncertainty associated with their performance. This study proposes a new application for the response surface method that allows modeling the initiation of erosion process with more accurate failure mechanisms and more complex subsurface geometry. The response surface–Monte Carlo (RSMC) simulation method uses finite-element analyses to develop a series of equations that define the relationship between the variables and the factor of safety (F). Using these equations, probability density functions (PDF) for variables, and the computer program @Risk, a Monte Carlo simulation is performed to calculate the conditional probability of unsatisfactory performance because of underseepage for a given river flood level. Two examples are presented to illustrate the proposed procedure. Multiple regression analyses are performed to assess the relative effect that changes in the input variables have on the F for the various analyses. The results suggest that uncertainty in the levee geometry has the greatest effect on the variation of the F for the cases studied. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000650