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Uplift performance of anchor plates embedded in cement-stabilized backfill / Nilo Cesar Consoli in Journal of geotechnical and geoenvironmental engineering, Vol. 139 N° 3 (Mars 2013) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 511-517 Titre : Uplift performance of anchor plates embedded in cement-stabilized backfill Type de document : texte imprimé Auteurs : Nilo Cesar Consoli, Auteur ; Cesar Alberto Ruver, Auteur ; Fernando Schnaid, Auteur Année de publication : 2013 Article en page(s) : pp. 511-517 Note générale : geotechnique Langues : Anglais (eng) Mots-clés : uplifting;  cement;  in  situ  tests;  pullout;  backfills;  plates;  arches Résumé : A series of pullout tests is presented in this paper and is used to identify the kinematics of failure and the uplift response of circular anchor plates embedded in sand-cement stabilized layers at distinct normalized embedment depths (H/D), where H is the thickness of the treated layer and D is the diameter of the anchor plates. Experimental results show that the uplift capacity of anchor plates embedded in sand backfill layers increases considerably after mixing 3% cement with the backfill material. Distinct failure mechanisms observed for anchor plates embedded in both sand and cement-stabilized backfills are shown to be a function of H/D. The addition of cement to the sand backfill leads to an increase in uplift capacity of 9 times for an H/D ratio of 1.0 and of 13 times for an H/D ratio of 2.0. For sand backfill with H/D=1.0, the failure surface had a truncated cone shape with a vertical inclination of 22°, whereas for H/D of 1.5 and 2.0, radial cracking was observed, and final failure surfaces had inclinations of 26 and 30°, respectively. Pullout of anchor plates in cement-stabilized backfills at H/D ratios ranging from 1.0 to 2.0 exhibit two distinct characteristics: (a) a linear elastic deformation response at small pullout displacements and (b) a later stage where radial fracturing of the stabilized backfill leads to hardening just prior to failure. Radial cracks starting at the top of the layer near the center of the anchor plates start to propagate only at about 90% of the final uplift failure load, irrespective of H/D. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000785 [article] Uplift performance of anchor plates embedded in cement-stabilized backfill [texte imprimé] / Nilo Cesar Consoli, Auteur ; Cesar Alberto Ruver, Auteur ; Fernando Schnaid, Auteur . - 2013 . - pp. 511-517. geotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 139 N° 3 (Mars 2013) . - pp. 511-517 Mots-clés : uplifting;  cement;  in  situ  tests;  pullout;  backfills;  plates;  arches Résumé : A series of pullout tests is presented in this paper and is used to identify the kinematics of failure and the uplift response of circular anchor plates embedded in sand-cement stabilized layers at distinct normalized embedment depths (H/D), where H is the thickness of the treated layer and D is the diameter of the anchor plates. Experimental results show that the uplift capacity of anchor plates embedded in sand backfill layers increases considerably after mixing 3% cement with the backfill material. Distinct failure mechanisms observed for anchor plates embedded in both sand and cement-stabilized backfills are shown to be a function of H/D. The addition of cement to the sand backfill leads to an increase in uplift capacity of 9 times for an H/D ratio of 1.0 and of 13 times for an H/D ratio of 2.0. For sand backfill with H/D=1.0, the failure surface had a truncated cone shape with a vertical inclination of 22°, whereas for H/D of 1.5 and 2.0, radial cracking was observed, and final failure surfaces had inclinations of 26 and 30°, respectively. Pullout of anchor plates in cement-stabilized backfills at H/D ratios ranging from 1.0 to 2.0 exhibit two distinct characteristics: (a) a linear elastic deformation response at small pullout displacements and (b) a later stage where radial fracturing of the stabilized backfill leads to hardening just prior to failure. Radial cracks starting at the top of the layer near the center of the anchor plates start to propagate only at about 90% of the final uplift failure load, irrespective of H/D. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000785

Voids/cement ratio controlling tensile strength of cement-treated soils / Nilo Cesar Consoli in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 11 (Novembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1126-1131 Titre : Voids/cement ratio controlling tensile strength of cement-treated soils Type de document : texte imprimé Auteurs : Nilo Cesar Consoli, Auteur ; António Viana Da Fonseca, Auteur Année de publication : 2012 Article en page(s) : pp. 1126-1131 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Cemented  soil  Porosity  Tensile  strength  Compacted  soils  Voids/cement  ratio Résumé : The improvement of locally available soils with cement can provide great advantages, including avoiding the need to borrow volumes of appropriate material and disposing of the local soil in deposits. This research aims to quantify the influence of the amount of cement, the porosity, and the voids/cement ratio in the assessment of splitting tensile strength (qt), also known as indirect diametrical tensile (IDT) strength, of three distinct soils from Brazil and Portugal. From Brazil, clayey sand derived from Botucatu sandstone and uniform Osorio sand were considered; from Portugal, silty sand derived from weathered Porto granite was studied. A number of splitting tensile strength tests were carried out. The results show that qt increased with the amount of cement (C) and decreases in porosity (η) for the three soil-cement mixtures. A power function was well-adapted to fit both qt-C and qt-η. Finally, the tensile strength was plotted against the porosity/volumetric cement content relationship (η/Civ), in which volumetric cement content is adjusted by a different exponent depending on the soil (0.21 for Porto silty sand-cement mixtures, 0.28 for Botucatu clayey sand-cement mixtures, and 1.0 for Osorio sand-cement mixtures). These plots show unique correlations for each soil-cement mixture, indicating that the index property is a good parameter in the evaluation of the splitting tensile strength of the soils studied. As a consequence, for each of the three soil-cement mixtures studied, a target qt value could be obtained by both porosity reduction and cement increase. This experimental framework will enable a good definition of the mechanical parameters used in the design of foundations and subgrades of railways platforms, whose system failure mechanisms usually start under tensile stresses at the base of the improved layer, and in the execution quality control of such earthworks. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i11/p1126_s1?isAuthorized=no [article] Voids/cement ratio controlling tensile strength of cement-treated soils [texte imprimé] / Nilo Cesar Consoli, Auteur ; António Viana Da Fonseca, Auteur . - 2012 . - pp. 1126-1131. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 11 (Novembre 2011) . - pp. 1126-1131 Mots-clés : Cemented  soil  Porosity  Tensile  strength  Compacted  soils  Voids/cement  ratio Résumé : The improvement of locally available soils with cement can provide great advantages, including avoiding the need to borrow volumes of appropriate material and disposing of the local soil in deposits. This research aims to quantify the influence of the amount of cement, the porosity, and the voids/cement ratio in the assessment of splitting tensile strength (qt), also known as indirect diametrical tensile (IDT) strength, of three distinct soils from Brazil and Portugal. From Brazil, clayey sand derived from Botucatu sandstone and uniform Osorio sand were considered; from Portugal, silty sand derived from weathered Porto granite was studied. A number of splitting tensile strength tests were carried out. The results show that qt increased with the amount of cement (C) and decreases in porosity (η) for the three soil-cement mixtures. A power function was well-adapted to fit both qt-C and qt-η. Finally, the tensile strength was plotted against the porosity/volumetric cement content relationship (η/Civ), in which volumetric cement content is adjusted by a different exponent depending on the soil (0.21 for Porto silty sand-cement mixtures, 0.28 for Botucatu clayey sand-cement mixtures, and 1.0 for Osorio sand-cement mixtures). These plots show unique correlations for each soil-cement mixture, indicating that the index property is a good parameter in the evaluation of the splitting tensile strength of the soils studied. As a consequence, for each of the three soil-cement mixtures studied, a target qt value could be obtained by both porosity reduction and cement increase. This experimental framework will enable a good definition of the mechanical parameters used in the design of foundations and subgrades of railways platforms, whose system failure mechanisms usually start under tensile stresses at the base of the improved layer, and in the execution quality control of such earthworks. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i11/p1126_s1?isAuthorized=no