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Strength of weakly cemented sands from drained multistage triaxial tests / M. S. Ravi Sharma in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1202-1210 Titre : Strength of weakly cemented sands from drained multistage triaxial tests Type de document : texte imprimé Auteurs : M. S. Ravi Sharma, Auteur ; Christopher D. P. Baxter, Auteur ; Kathryn Moran, Auteur Année de publication : 2012 Article en page(s) : pp. 1202-1210 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Portland  cement  Silts  Sand  Volume  change  Shear  strength  Triaxial  tests  Wave  velocity Résumé : Characterizing the strength of weakly cemented and sensitive soils in the laboratory is difficult because of the difficulty in obtaining high-quality replicate samples necessary for defining the failure envelope. Multistage triaxial tests have long been used to reduce the variability caused by testing multiple samples; however, traditional criteria used for transitioning from one loading stage to another often lead to destructuring or failure in sensitive or structured soils. The objective of this paper is to present a methodology for conducting multistage drained triaxial tests on weakly cemented sands and estimating the resulting shear strength parameters. Both multistage and single-stage drained triaxial tests were performed on artificially cemented samples of a silty sand at two levels of densities and cementation. The use of dεv/dεa = 0 as a termination criterion to move on to the next stage of loading and εv = 0 as the failure criterion for the final stage of the shear resulted in an average error of 6% and 5% in c′ and φ′, respectively, for the stress range considered in this study when compared with parameters obtained from the single-stage drained triaxial tests. Continuous shear wave velocity (Vs) measurements during shear showed that destructuring of the cemented samples did not occur by using the proposed termination criterion. The proposed method has the potential to be a cost-effective alternative to the testing of multiple samples for the characterization of the strength of weakly cemented and sensitive soils. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1202_s1?isAuthorized=no [article] Strength of weakly cemented sands from drained multistage triaxial tests [texte imprimé] / M. S. Ravi Sharma, Auteur ; Christopher D. P. Baxter, Auteur ; Kathryn Moran, Auteur . - 2012 . - pp. 1202-1210. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1202-1210 Mots-clés : Portland  cement  Silts  Sand  Volume  change  Shear  strength  Triaxial  tests  Wave  velocity Résumé : Characterizing the strength of weakly cemented and sensitive soils in the laboratory is difficult because of the difficulty in obtaining high-quality replicate samples necessary for defining the failure envelope. Multistage triaxial tests have long been used to reduce the variability caused by testing multiple samples; however, traditional criteria used for transitioning from one loading stage to another often lead to destructuring or failure in sensitive or structured soils. The objective of this paper is to present a methodology for conducting multistage drained triaxial tests on weakly cemented sands and estimating the resulting shear strength parameters. Both multistage and single-stage drained triaxial tests were performed on artificially cemented samples of a silty sand at two levels of densities and cementation. The use of dεv/dεa = 0 as a termination criterion to move on to the next stage of loading and εv = 0 as the failure criterion for the final stage of the shear resulted in an average error of 6% and 5% in c′ and φ′, respectively, for the stress range considered in this study when compared with parameters obtained from the single-stage drained triaxial tests. Continuous shear wave velocity (Vs) measurements during shear showed that destructuring of the cemented samples did not occur by using the proposed termination criterion. The proposed method has the potential to be a cost-effective alternative to the testing of multiple samples for the characterization of the strength of weakly cemented and sensitive soils. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1202_s1?isAuthorized=no

Use of A = 0 as a failure criterion for weakly cemented soils / Christopher D. P. Baxter in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 161-170 Titre : Use of A = 0 as a failure criterion for weakly cemented soils Type de document : texte imprimé Auteurs : Christopher D. P. Baxter, Auteur ; M. S. Ravi Sharma, Auteur ; Kathryn Moran, Auteur Année de publication : 2011 Article en page(s) : pp. 161-170 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Portland  cement  Silts  Sand  Shear  strength  Dilatancy  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is considerable uncertainty in the determination of effective stress strength parameters of cemented soils from undrained triaxial tests. Large negative excess pore pressures are generated at relatively large strains (typically 4–5% for cemented silty sand) in isotropically consolidated undrained (CIU) tests, which results in gas coming out of solution during shear and significant variability in the measured peak deviator stress. In this study, different failure criteria for weakly cemented sands were evaluated based on the results of CIU and isotropically consolidated drained triaxial compression tests conducted on samples of artificially cemented sand. The use of math = 0 as a failure criterion eliminates the variability between the undrained tests and also ensures that the mobilized failure strength is not based on the highly variable negative excess pore pressures. In addition, the resulting strains to failure are comparable to the strains to failure for the drained tests. Mohr-Coulomb strength parameters thus estimated from the undrained tests are generally lower than strength parameters obtained from drained tests, and the difference between the failure envelopes from undrained tests increases as the level of cementation increases. This divergence is attributed to differences in the stiffness of the cemented soil under the different loading conditions. The stiffness under undrained loading conditions decreases with increasing cementation due to an increase in the generation of positive excess pore pressure at low strains. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p161_s1?isAuthorized=no [article] Use of A = 0 as a failure criterion for weakly cemented soils [texte imprimé] / Christopher D. P. Baxter, Auteur ; M. S. Ravi Sharma, Auteur ; Kathryn Moran, Auteur . - 2011 . - pp. 161-170. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 2 (Fevrier 2011) . - pp. 161-170 Mots-clés : Portland  cement  Silts  Sand  Shear  strength  Dilatancy  Stiffness Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : There is considerable uncertainty in the determination of effective stress strength parameters of cemented soils from undrained triaxial tests. Large negative excess pore pressures are generated at relatively large strains (typically 4–5% for cemented silty sand) in isotropically consolidated undrained (CIU) tests, which results in gas coming out of solution during shear and significant variability in the measured peak deviator stress. In this study, different failure criteria for weakly cemented sands were evaluated based on the results of CIU and isotropically consolidated drained triaxial compression tests conducted on samples of artificially cemented sand. The use of math = 0 as a failure criterion eliminates the variability between the undrained tests and also ensures that the mobilized failure strength is not based on the highly variable negative excess pore pressures. In addition, the resulting strains to failure are comparable to the strains to failure for the drained tests. Mohr-Coulomb strength parameters thus estimated from the undrained tests are generally lower than strength parameters obtained from drained tests, and the difference between the failure envelopes from undrained tests increases as the level of cementation increases. This divergence is attributed to differences in the stiffness of the cemented soil under the different loading conditions. The stiffness under undrained loading conditions decreases with increasing cementation due to an increase in the generation of positive excess pore pressure at low strains. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i2/p161_s1?isAuthorized=no