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Comparison between models of rock discontinuity strength and deformation / D. A. F. Oliveira in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 6 (Juin 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 6 (Juin 2010) . - pp. 864-874 Titre : Comparison between models of rock discontinuity strength and deformation Type de document : texte imprimé Auteurs : D. A. F. Oliveira, Auteur ; B. Indraratna, Auteur Année de publication : 2010 Article en page(s) : pp. 864-874 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Rock  joint  models  Soil-infill  Shear-displacement  behavior  Numerical  modeling  Tunneling Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : One important component in the design of tunnels in urban areas is a correct assessment of the interaction between the underground excavation with other structures in the vicinity. In this sense a correct stress-strain response by the model representing the rock mass behavior is essential. The shear and normal displacement of rock discontinuities and their shear and normal stiffness control the distribution of stress and displacement within a discontinuous rock mass. In conditions where an equivalent continuum based approach is not applicable, the joint material model should be able to describe important mechanisms such as asperity sliding and shearing, post-peak behavior, asperity deformation, and the effect of soft infilling. The distinct element code UDEC was used to simulate the direct shear tests on a natural joint profile, and the prediction of two existing models of discontinuity strength and deformation were then compared with a new soil-infilled joint model and with experimental data for clean and soil-infilled rock joints. A numerical modeling of a cavern excavated in a jointed medium is also presented to illustrate the response of different models. The proposed soil-infilled joint model described more comprehensively the occurrence of dilation and compression with lateral displacements and also better represented the double peak shearing in relation to the adopted squeezing mechanism that could not be captured by the two existing models. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i6/p864_s1?isAuthorized=no [article] Comparison between models of rock discontinuity strength and deformation [texte imprimé] / D. A. F. Oliveira, Auteur ; B. Indraratna, Auteur . - 2010 . - pp. 864-874. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 6 (Juin 2010) . - pp. 864-874 Mots-clés : Rock  joint  models  Soil-infill  Shear-displacement  behavior  Numerical  modeling  Tunneling Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : One important component in the design of tunnels in urban areas is a correct assessment of the interaction between the underground excavation with other structures in the vicinity. In this sense a correct stress-strain response by the model representing the rock mass behavior is essential. The shear and normal displacement of rock discontinuities and their shear and normal stiffness control the distribution of stress and displacement within a discontinuous rock mass. In conditions where an equivalent continuum based approach is not applicable, the joint material model should be able to describe important mechanisms such as asperity sliding and shearing, post-peak behavior, asperity deformation, and the effect of soft infilling. The distinct element code UDEC was used to simulate the direct shear tests on a natural joint profile, and the prediction of two existing models of discontinuity strength and deformation were then compared with a new soil-infilled joint model and with experimental data for clean and soil-infilled rock joints. A numerical modeling of a cavern excavated in a jointed medium is also presented to illustrate the response of different models. The proposed soil-infilled joint model described more comprehensively the occurrence of dilation and compression with lateral displacements and also better represented the double peak shearing in relation to the adopted squeezing mechanism that could not be captured by the two existing models. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i6/p864_s1?isAuthorized=no

A shear-displacement criterion for soil-infilled rock discontinuities / B. Indraratna in Géotechnique, Vol. 60 N° 8 (Août 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 8 (Août 2010) . - pp. 623–633 Titre : A shear-displacement criterion for soil-infilled rock discontinuities Type de document : texte imprimé Auteurs : B. Indraratna, Auteur ; D. A. F. Oliveira, Auteur ; E. T. Brown, Auteur Année de publication : 2011 Article en page(s) : pp. 623–633 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shear  strength  Clays  Laboratory  tests  Rocks/rock  mechanics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An infilled rock joint is likely to be the weakest plane in a rock mass. The most pronounced effect of the presence of infill material is the reduction in friction of the discontinuity boundaries (i.e. rock to rock contact of the joint walls). The thicker the infill, the smaller the shear strength of the rock joint. Once the infill reaches a critical thickness, the joint walls (rock) play no significant role in the overall shear strength. Several models have been proposed to predict the peak shear strength of infilled joints under both constant normal load and constant normal stiffness boundary conditions, taking into account the ratio of infill thickness (t) to the height of the joint wall asperity (a), that is the t/a ratio. Models based on the constant normal stiffness condition provide a much more accurate representation of the infilled joint behaviour in the field, but only a limited number of studies have focused on the more realistic constant normal stiffness stress–strain behaviour. This paper presents a critical review of some of the earlier studies and the most recent advancement of a shear-strength model developed at University of Wollongong, Australia, supplemented with laboratory data for model validation. The effect of different factors on the shear behaviour such as the t/a ratio, infill friction angle, joint wall roughness, joint stiffness and type of infill are presented. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.094 [article] A shear-displacement criterion for soil-infilled rock discontinuities [texte imprimé] / B. Indraratna, Auteur ; D. A. F. Oliveira, Auteur ; E. T. Brown, Auteur . - 2011 . - pp. 623–633. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 8 (Août 2010) . - pp. 623–633 Mots-clés : Shear  strength  Clays  Laboratory  tests  Rocks/rock  mechanics Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An infilled rock joint is likely to be the weakest plane in a rock mass. The most pronounced effect of the presence of infill material is the reduction in friction of the discontinuity boundaries (i.e. rock to rock contact of the joint walls). The thicker the infill, the smaller the shear strength of the rock joint. Once the infill reaches a critical thickness, the joint walls (rock) play no significant role in the overall shear strength. Several models have been proposed to predict the peak shear strength of infilled joints under both constant normal load and constant normal stiffness boundary conditions, taking into account the ratio of infill thickness (t) to the height of the joint wall asperity (a), that is the t/a ratio. Models based on the constant normal stiffness condition provide a much more accurate representation of the infilled joint behaviour in the field, but only a limited number of studies have focused on the more realistic constant normal stiffness stress–strain behaviour. This paper presents a critical review of some of the earlier studies and the most recent advancement of a shear-strength model developed at University of Wollongong, Australia, supplemented with laboratory data for model validation. The effect of different factors on the shear behaviour such as the t/a ratio, infill friction angle, joint wall roughness, joint stiffness and type of infill are presented. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.094