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This paper presents a unified critical state parameter model for evaluating sand and overconsolidated clay, which is named as CASM-S. The model is formulated in terms of the modification of the clay and sand model, i.e., CASM, by incorporating the subloading surface theory with an overconsolidation state parameter R. Although the standard CASM proves to be useful in modelling overconsolidated clay and sand, the model (1) requires the rate of overconsolidated ratio to be constant which is in contrast to the observed behaviour of soils and (2) only allows elastic deformation to develop at the overconsolidated state that may underestimate the deformation corresponding to the peak stress or be unable to predict the actual stress path. By introducing a new material parameter u to those material properties of the standard CASM, the rate relationship of stress–strain for the CASM-S model is developed. The standard CASM can be either recovered or approximated as a special case of the overconsolidation state assumed in the CASM-S. The numerical integration of the newly proposed model is performed by the modified forward Euler method. Validation with undrained and drained overconsolidated clay and sand have demonstrated the capability of the CASM-S model to well predict the observed soil behaviours. [ABSTRACT FROM AUTHOR]

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This paper discusses the geotechnical properties of two families of transparent silica, which can be used to model soil structure interaction and flow problems in transparent soil models. The fundamental premise of this research is that these materials can be used in model tests to study three-dimensional deformation and flow problems, using nonintrusive optical visualization techniques. Triaxial, direct shear, consolidation, and permeability tests conducted in this study indicate that transparent silica gels and amorphous silica have macroscopic geotechnical properties consistent with those of sands and clays, respectively. The materials used in this research have the same refractive index, which permits combining both families in a stratified transparent soil model. The transparent soils described in this paper represent the only system of transparent materials capable of resembling soils that have a wide range of grain sizes including sand and clay using the same pore fluid.Key words : imaging, optical, silica gel, amorphous silica, clay, sand, modeling.Cet article discute des propriétés géotechniques de deux familles de silices transparentes qui peuvent être utilisées pour modéliser l'interaction de la structure du sol et les problèmes d'écoulement dans les modèles de sols transparents. La prémisse de base de cette recherche est que ces matériaux peuvent être utilisés dans des essais sur modèle pour étudier la déformation à trois dimensions et les problèmes d'écoulement en utilisant des techniques optiques de visualisation non destructrices. Les essais triaxiaux, de cisaillement direct, de consolidation et de perméabilité réalisés dans cette étude indiquent que les gels de silice transparente et la silice amorphe ont des propriétés géotechniques macroscopiques qui sont consistantes avec celles des sables et des argiles respectivement. Les matériaux utilisés dans cette recherche ont le même indice de réfraction, ce qui permet de combiner les deux familles de silice dans une modèle de sol stratifié transparent. Les sols transparents décrits dans cet article représente le seul système de matériaux transparents qui puisse ressembler aux sols ayant une large plage de dimensions de grains incluant le sable et l'argile et utilisant le même fluide interstitiel.Mots clés : imagerie, optique, gel de silice, silice amorphe, argile, sable, modélisation.[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.)

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.)

The author discusses the article "Influence of State and Compressibility on Liquefied Strength of Sands" by A. Sadrekarimi which was published in a previous issue. He talks about shear-expressed pore-water pressure and the difficulty in determining yield shear strength of soft clays and loose sands. He comments on the difficulty in determining the state and compressibility parameters for liquefiable sand deposits.

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.)

Four different seismic methods were used extensively to evaluate the shear wave velocity of soils and rock in the city of Ottawa, Canada, from which the travel-time weighted average shear wave velocity (Vs) from surface to 30 m in depth (Vs30) and the fundamental frequency (F0) were computed. Three main geological or geotechnical units were identified with distinct shear wave velocities: these consist of very loose thick post-glacial fine-grained sands, silts, and clays (Vs <150 m/s, thickness up to 110 m), firm glacial sediments (Vs ~580 m/s, thickness ~3 m), and very firm bedrock (Vs ~1750-3550 m/s). The seismic methods applied were downhole interval Vs measurements at 15 borehole sites, seismic refraction-reflection profile measurements for 686 sites, high-resolution shear wave reflection 'landstreamer' profiling for 25 km in total, and horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise to evaluate the fundamental frequency for ~400 sites. Most of these methods are able to distinguish the very high shear wave impedance of and depth to bedrock. Sparse earthquake recordings show that the soil amplification is large for weak motion when the soil behaves linearly. Quatre méthodes sismiques différentes ont été grandement utilisées afin d'évaluer la vitesse des ondes de cisaillement des sols et roches dans la ville d'Ottawa, Canada, à partir desquelles la vitesse moyenne des ondes de cisaillement pondérée selon le temps de parcours (Vs) de la surface jusqu'à une profondeur de 30 m (Vs30) et la fréquence fondamentale (F0) ont été calculées. Trois unités géologiques ou géotechniques principales ont été identifiées selon des vitesses des ondes de cisaillement distinctes : des sables, silts et argiles post-glaciaires fins, lâches et épais (Vs <150 m/s, jusqu'à 110 m d'épaisseur), des sédiments glaciaires fermes (Vs ~580 m/s, ~3 m d'épaisseur) et du substratum rocheux très ferme (Vs ~1750-3550 m/s). Les méthodes sismiques appliquées étaient des mesures de Vs par intervalle en fond de forage pour 15 sites de forage, des mesures du profil de réfraction-réflexion sismique pour 686 sites, du profilage de la réflexion des ondes de cisaillement à haute résolution « landstreamer » pour 25 km linéaire au total, et le ratio spectral horizontal-vertical (RSHV) du bruit sismique ambiant pour l'évaluation de la fréquence fondamentale sur environ 400 sites. La majorité de ces méthodes sont capables de distinguer l'impédance très élevée aux ondes de cisaillement et la profondeur jusqu'au substratum rocheux. Quelques mesures de séismes montrent que l'amplification du sol est grande pour des mouvements faibles lorsque le sol de comporte de façon linéaire. [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.)

Two large-scale sealing experiments were conducted at Atomic Energy of Canada Limited's Underground Research Laboratory at Lac du Bonnet, Manitoba. The rate of water uptake in densely compacted sand–clay buffer materials proposed for use in a deep geologic repository for spent nuclear fuel was monitored. The buffer–container experiment examined the influence of heat on the performance of a large mass of buffer. Temperatures, water contents, and total and hydraulic pressures within and surrounding the installation were monitored for approximately 2.5 years. Local groundwater pressures increased as a result of rising temperatures. Water uptake and redistribution occurred in the buffer due to drying shrinkage close to the heater and counter-acted swelling due to an increase in water content near the rock–buffer interface. The isothermal test (ITT) allowed natural groundwater uptake from the surrounding rock mass under isothermal conditions. It was monitored for a period of 6.5 years and is the first, and longest running test of its kind yet conducted in the world. During its operation, the ITT (for as yet unconfirmed reasons) experienced a 35% decrease in the rate of water supply relative to that measured prior to experiment installation. This decrease impacts on the time required for saturation to be achieved.Key words: buffer, bentonite, underground research laboratory, instrumentation.Deux essais d'étanchéité à grande échelle ont été conduits au Laboratoire de recherche souterrain de l'Énergie atomique du Canada au lac du Bonnet, Manitoba. On a mesuré la vitesse d'absorption d'eau dans des matériaux tampons formés de sable et argile densément compacts devant être utilisés dans un dépôt géologique profond pour le combustible nucléaire irradié. L'expérience tampon–conteneur a permis d'examiner l'influence de la chaleur sur la performance d'une large masse de tampon. Les températures, teneurs en eau, pressions totales et hydrauliques à l'intérieur et autour de l'installation ont été mesurées durant environ 2,5 années. Les pressions de l'eau souterraine locale ont augmenté à cause de l'augmentation de la température, une absorption et une redistribution se sont produites dans le tampon à cause du séchage et du retrait près des points chauds d'une part, et de l'action inverse du gonflement dû à l'augmentation de la teneur en eau près de l'interface roc–tampon d'autre part. L'essai isothermique a permis l'absorption de l'eau souterraine naturelle venant du massif rocheux dans des conditions isothermiques. Des mesures ont été prises durant une période de 6,5 années, et cet essai est le premier et le plus long essai de ce type à être réalisé jusqu'à ce jour dans le monde. Au cours de son opération, cet essai a subi, pour des raisons encore non confirmées, une diminution de 35 % de la vitesse de son alimentation en eau par rapport à celle mesurée avant la mise en place de l'expérience. Ceci a des impacts sur le temps requis pour atteindre la saturation.Mots clés : tampon, bentonite, Laboratoire de recherche souterrain, instrumentation.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The intrinsic behaviour of a residual clayey sand derived from sandstone was investigated in one-dimensional compression. The data show some interesting differences when compared with other published data, in that no unique normal compression line can be identified. Although the compressibility on first loading is similar to that for many sandy materials at states on their normal compression lines, the locations of the compression curves were found to be a function of the initial voids ratio, and there was no convergence at higher stresses. Tests on a model clay-sand mixture indicated that this behaviour is common to gap-graded clayey sands.Key words: sands, compressibility, oedometer tests.Le comportement intrinsèque d'un sable argileux résiduel dérivé d'un grès a été étudié en compression unidimensionnelle. Les données montrent des différences intéressantes lorsque comparées avec d'autres données publiées, en ce qu'une ligne de compression normale unique ne peut être identifiée. Quoique la compressibilité durant le premier chargement est similaire à celle de plusieurs matériaux sableux dans des points localisés sur les lignes de compression normale, on a trouvé que les positions des courbes de compression étaient fonction de l'indice de vide initial, et qu'il n'y avait pas de convergence aux contraintes plus élevées. Des essais sur un mélange modèle argile-sable ont indiqué que ce comportement est typique des sables argileux à granulométrie discontinue.Mots clés : sables, compressibilité, essais oedométriques. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]