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Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper examines the constitutive behaviour of unsaturated mixtures of compacted sand-bentonite material. Two different techniques have been used to modify soil suction in laboratory specimens to examine the influence of suction on the behaviour of compacted materials. The two methods generated inherent differences in material fabric and therefore in stress-strain behaviour. The difference in microstructure generated by these two preparation techniques created different properties for the two series of specimens. This paper compares the behaviour of the two series of specimens and relates the observed mechanical behaviour to the initial soil fabric created by the two different preparation techniques. Specimens of similar compacted material were taken from two full-scale in-ground experiments conducted at Atomic Energy of Canada Limited's Underground Research Laboratory at Lac du Bonnet, Manitoba and sheared using the same triaxial equipment. The results are compared to the results of shearing laboratory compacted specimens. The research program demonstrates the need to understand the initial volume and suction states of plastic clays in order to predict the change in mechanical behaviour following a change in water content.Key words: constitutive relationships, unsaturation, laboratory tests, expansive soils, clays, shear strength.Cet article examine la loi de comportement de mélanges non saturés d'un matériau formé de sable-bentonite. Deux techniques différentes ont été utilisées pour modifier la succion du sol dans des spécimens en laboratoire afin d'examiner l'influence de la succion sur le comportement des matériaux compactés. Les deux méthodes ont généré des différences inhérentes dans la fabrique du matériau, et en conséquence, dans le comportement contrainte- déformation. La différence dans la microstructure générée par ces deux techniques de préparation ont créé de façon inhérente des propriétés différentes pour les deux séries de spécimens. Cet article compare le comportement des deux séries de spécimens et met en relation le comportement mécanique observé avec la fabrique initiale du sol créée par les deux différentes techniques de préparation. Des spécimens de matériaux compactés similaires ont été prélevés de deux expériences à grande échelle réalisées sur le terrain au laboratoire de recherche souterraine de l'AECL, et ont été cisaillés au moyen du même équipement triaxial. Les résultats sont comparés à ceux obtenus sur des spécimens compactés et cisaillés en laboratoire. Les résultats du programme de recherche démontrent le besoin de comprendre les états initiaux de volume et de contraintes dans les argiles plastiques pour prédire le changement dans le comportement mécanique à la suite d'un changement dans la teneur en eau.Mots clés : lois de comportement, non saturation, essais en laboratoire, sols gonflants, argiles, résistance au cisaillement.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A linear logarithm–logarithm model for the fall cone penetration depth versus water content relationship (flow curve) has been developed based on the results of an experimental study using the British fall cone apparatus. The fall cone flow curve is expressed by a simple equation with parameters m and c, which represent the slope of the flow curve and the water content at a penetration depth of 1 mm, respectively. For a soil, the flow curve can be determined by applying a linear regression analysis to at least four data points with penetration depths approximately evenly distributed between 25 and 3 mm. It is shown in this paper that both the liquid limit and the plastic limit determined from the linear logarithm–logarithm flow curve are in close agreement with those determined from conventional methods. A one-point method for determination of the liquid limit is developed from the model and is verified by applying statistical analysis to a large volume of experimental data.Key words: fall cone, laboratory tests, consistency limits, clays.Un modèle linéaire log–log pour la relation entre la profondeur de pénétration du cône tombant et la teneur en eau (courbe d'écoulement) a été développé en partant des résultats d'une étude expérimentale utilisant l'appareil britannique du cône tombant. La courbe d'écoulement du cône tombant est exprimée par une simple équation avec les paramètres m et c, qui représentent respectivement la pente de la courbe d'écoulement et la teneur en eau à la profondeur de pénétration de 1 mm. Pour un sol donné, la courbe d'écoulement peut être déterminée en appliquant une analyse de régression linéaire comprenant au moins quatre points correspondant à des profondeurs de pénétration distribuées à peu près uniformément entre 25 mm et 3 mm. Il est montré dans cet article que tant la limite de liquidité que la limite de plasticité déterminées par la courbe d'écoulement log–log linéaire se situent très près des valeurs déterminées par les méthodes conventionnelles. Une méthode à point unique a été développée en partant du modèle pour déterminer la limite de liquidité et a été vérifiée an appliquant une analyse statistique sur un grand volume de données expérimentales.Mots clés : cône tombant, essais de laboratoire, limites de consistance, argiles.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

This paper presents a novel analysis for the interpretation of pressuremeter tests in clay. No prior knowledge of the constitutive properties of the material is required. Shear, radial, and tangential stresses are determined at various distances from the probe and for different levels of cavity strain. Total and effective stress paths followed by material elements within the deformed soil are represented on shear stress – normal stress diagrams. The analysis is applied to the interpretation of pressuremeter tests carried out in both the field and the laboratory.Key words: pressuremeter tests, clays, novel analysis, stress–strain curves, stress distributions, stress paths.Cet article présente une nouvelle méthode d'interprétation d'essais pressiométriques dans l'argile. Aucune connaissance préalable des propriétés constitutives du matériau n'est requise. Les contraintes de cisaillement, radiales et tangentielles sont déterminées à diverses distances de la sonde et pour différents niveaux de déformation. Les cheminements de contraintes totales et effectives suivis par des éléments de sol sont représentés sur des graphiques de type Mohr–Coulomb. L'analyse proposée est appliquée à l'interprétation d'essais pressiométriques effectués in situ et au laboratoire.Mots clés : essais pressiométriques, argiles, nouvelle méthode, courbes contrainte–déformation, distributions et cheminements de contraintes. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An organic–inorganic nanohybrid material was prepared by grafting glycidol (2,3-epoxy-1-propanol) on the interlayer aluminol groups of kaolinite (K) using DMSO–K precursor as a starting material. The results of the physicochemical characterization of the synthesized materials (XRD, FTIR, DTA–TG, 13C and 29Si CP/MAS NMR) confirm that the grafting reaction of glycidol involved the opening of the oxirane ring. The resulting nanohybrid material is similar to the one obtained by the interlayer grafting of glycerol (M. Janek, K. Emmerich, S. Heissler, and R. Nüesch. Chem. Mater. 19, 684, (2007)). Approximately, one glycidol moiety is grafted on each structural unit of kaolinite to afford a material with the chemical composition Al2Si2O5(OH)4[C3H6O2]0.9.Key words: clays, clay minerals, kaolinite, intercalation, grafting, nanohybrid materials, DMSO, glycidol, glycerol, oxirane. Un matériau nanohybride organo–inorganique a été obtenu par greffage du glycidol (2,3-époxy-1-propanol) sur les groupements aluminol interfoliaires de la kaolinite (K), à partir des précurseurs DMSO–K. Les résultats de la caractérisation physico-chimique des matériaux synthétisés (DRX, IRTF, ATD–TG, RMN PC/RAM du 13C et du 29Si) confirment que la réaction de greffage du glycidol met en jeu l’ouverture de l’anneau oxirane. Le matériau nanohybride résultant est semblable à celui obtenu par le greffage interfoliaire du glycerol (M. Janek, K. Emmerich, S. Heissler, and R. Nüesch. Chem. Mater. 19, 684, (2007)). Approximativement une unité de glycidol est greffée sur chaque unité structurale de la kaolinite pour donner un matériau de composition chimique Al2Si2O5(OH)4[C3H6O2]0.9.Mots-clés : argiles, minéraux argileux, kaolinite, intercalation, greffage, matériaux nanohybrides, DMSO, glycidol, glycérol, oxirane. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A theoretical study of the behaviour of structured soil is presented. A new model, referred to as the Structured Cam Clay model, is formulated by introducing the influence of soil structure into the Modified Cam Clay model. The proposed model is hierarchical, i.e., it is identical to the Modified Cam Clay soil model if a soil has no structure or if its structure is removed by loading. Three new parameters describing the effects of soil structure are introduced, and the results of a parametric study are also presented. The proposed model has been used to predict the behaviour of structured soils in both compression and shearing tests. By making comparisons of predictions with experimental data and by conducting the parametric study it is demonstrated that the new model provides satisfactory qualitative and quantitative modelling of many important features of the behaviour of structured soils.Key words: calcareous soils, clays, fabric, structure, constitutive relations, plasticity.On présente une étude théorique sur le comportement du sol structuré. On formule un nouveau modèle auquel on réfère comme le modèle Cam Clay structuré en introduisant l'influence de la structure du sol dans le modèle Cam Clay modifié. Le modèle proposé est hiérarchique, i.e., il est identique au modèle de sol Cam Clay modifié si un sol n'a pas de structure ou si sa structure est éliminé par chargement. Trois nouveaux paramètres décrivant les effets de la structure du sol sont introduits et les résultats d'une étude paramétrique sont également présentés. Le modèle proposé a été utilisé pour prédire le comportement des sols structurés dans les essais de compression et de cisaillement. En faisant des comparaisons de prédictions avec des données expérimentales et en conduisant un étude paramétrique, il est démontré que le nouveau modèle fournit une modélisation qualitative et quantitative de plusieurs caractéristiques importantes du comportement des sols structurés.Mots clés : sols calcareux, argiles, fabrique, structure, relations de comportement, plasticité.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

A pilot test was carried out at a land reclamation project site to study the effect of vertical drains on the rate of consolidation of a marine clay deposit in Singapore. Theoretical and numerical analyses were conducted to interpret the field measurements of pore pressure and settlement, and consolidation parameters were back-calculated. The back-calculated preconsolidation pressure is similar to that obtained from the laboratory consolidation test on undisturbed samples, but the field-deduced compression index is generally larger than that measured in the laboratory. The coefficient of consolidation back-calculated from the settlement measurement is larger than that from the pore-pressure measurement. The coefficient of consolidation for horizontal flow obtained from the Rowe cell test, which is comparable to that back-calculated from the field settlement measurement, is recommended for the preliminary design of vertical drains without the need of considering the smear effect.Key words: clays, consolidation, ground improvement, numerical modelling and analysis, permeability, vertical drains.Un essai pilote a été réalisé sur le site d'un projet de réhabilitation de terrain pour étudier l'effet des drains verticaux sur la vitesse de consolidation d'un dépôt d'argile marine à Singapore. Des analyses théorique et numérique ont été réalisées pour interpréter les mesures sur le terrain de la pression interstitielle et du tassement, et des paramètres de consolidation ont été calculés à rebours. La pression de consolidation calculée à rebours est similaire à celle obtenue par l'essai de consolidation en laboratoire sur des échantillons non remaniés, mais l'indice de compression déduit du terrain est généralement plus grand que celui mesuré en laboratoire. Le coefficient de consolidation calculé à rebours à partir des mesures de tassement est plus grand que celui obtenu par la mesure de la pression interstitielle. Le coefficient de consolidation pour l'écoulement horizontal obtenu par l'essai avec la cellule de Rowe, qui est comparable à celui calculé à rebours à partir de la mesure du tassement sur le terrain, est recommandé pour la conception préliminaire des drains verticaux sans prendre en compte l'effet de souillure d'argile remaniée.Mots clés : argiles, consolidation, amélioration des terrains, modélisation et analyse numériques, perméabilité, drains verticaux.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

An investigation and remediation of instability along cut slopes of an irrigation canal in salt-rich clayey colluvium in southern Alberta is described. Random sloughing of the canal side slopes began to occur 2 years after construction over a 7500 m length of canal and was nearly continuous over a 2500 m length 3 years later. The sloughs are shallow seated and most had the appearance of a "mud" flow. Soil salinity also developed along the canal slopes due to capillarity and evaporation. Failure of the clay slopes in the cut sections is attributed to swelling, dispersion, and softening of the subgrade due to exposure of the salt-laden clays to fresh water. In contrast, 600 m of salt-rich clayey colluvium compacted as a clay liner on the canal side slopes showed no evidence of sloughing and salt loading after 9 years of service. Good soil compaction inhibited softening and slope instability in these salt-rich soils. Results from detailed site investigations and observations, and the interplay of soil chemistry and geology, facilitated the selection of a satisfactory method of repair. Repairs consisted of reconstructing 2500 m of canal by overexcavating the canal subgrade and replacing those soils with compacted soil.Key words: clays, salts, dispersive, sloughing, salinity, compaction.On présente une étude et un comfortement de l'instabilité le long de pentes excavées d'un canal d'irrigation dans les colluvions argileux riches en sel dans le sud de l'Alberta. Des glissements superficiels aléatoires dans les pentes latérales du canal ont commencé à se produire 2 ans après la construction sur une longueur de 7500 m de canal et étaient quasiment continus sur une longueur de 2500 m après 3 ans. Les surfaces de glissement sont peu profondes, et la plupart avaient une apparence d'écoulements de boue. La salinité du sol s'est accentuée le long des pentes du canal à cause de la capillarité et de l'évaporation. La rupture des pentes argileuses dans les sections excavées est attribuée au gonflement, à la dispersion, et au ramollissement de la fondation par suite de l'exposition à l'eau douce des argiles chargées de sel. Par opposition, 600 m de colluvions argileux riches en sel compactés comme membrane argileuse sur les pentes latérales du canal n'ont montré aucune évidence de glissement de surface et d'absorption de sel après 9 ans de service. Un bon compactage du sol a empêché le ramollissement et l'instabilité de la pente dans ces sols riches en sel. Les résultats des études et observations détaillées du site, et l'interaction de la chimie et de la géologie ont facilité la sélection d'une méthode satisfaisante de réparation. Les réparations ont consisté en la reconstruction de 2500 m de canal par surexcavation de la fondation du canal et le remplacement de ces sols par un sol compacté.Mots clés : argiles, sels, dipersive, glissement de surface, salinité, compactage.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]