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The Cambrian pre-salt dolomite sequence in the Tarim Basin is a target zone of great strategic significance for hydrocarbon exploration in the basin. Using the results of the interpretation of 3D seismic data from Lunnan and 2D seismic data covering the whole basin, and based on a synthesis of outcrop data, drilling data, well logs, core data, and thin-section data, and the findings from previous studies, this paper studies the characteristics of the facies of the Middle–Lower Cambrian in the platform area in the Tarim Basin, the formation and evolution of platform margins, and the sedimentary characteristics, lithofacies, and paleogeographic characteristics of the Middle–Lower Cambrian series. Based on the types of lithofacies and the seismic facies analysis, the sedimentary facies of the Middle–Lower Cambrian strata can be classified into the five types. From bottom to top, the Middle–Lower Cambrian have experienced several development stages, including the deposition of continental shelf sediments of the Yuertusi Formation, gently sloping non-rimmed platform margin sediments of the Xiaoerbulake Formation, weakly rimmed platform margin sediments of the Wusongger and Shayilike formations, and strongly rimmed platform margin sediments of the Awatage Formation. In each stage, the platform margin shifted further east relative to its location in the previous stage. Based on these results and previous studies, the lithofacies and paleogeography maps of the Middle–Lower Cambrian in the Tarim Basin are modified, and the implications for hydrocarbon exploration in this area are discussed. [ABSTRACT FROM AUTHOR]

Fines migration associated with the multiphase flow in the exploitation of hydrate-bearing sediments (HBS) usually induces local clogging and sand production around wells, and thus its behavior with multi-field coupling is of vital importance but still poorly discovered. This paper establishes a coupled thermo-hydro-mechanical-chemical (THMC) model incorporating fines migration in HBS from micro- to macro-scale. Two typical hydrate pore habits, i.e., grain coating and pore filling, are simulated with the discrete element method (DEM) under different depressurization modes, water flow is simulated using computational fluid dynamics (CFD), and heat transfer and chemical reactions are also considered in coupled CFD-DEM simulations. Two distinct fines migration modes and their consequence on the mechanical and hydromechanical properties are revealed. For the grain-coating habit, the coarse particle size reduction induced by hydrate dissociation under an intense depressurization decreases the constriction size, increasing the local pore-clogging probability and reducing the growth rate of the hydraulic conductivity. Conversely, the fine particle size reduction in the pore-filling habit facilitates fines migration and thus sand production, with hydromechanical properties of HBS evolving oppositely compared to the clogging case. [ABSTRACT FROM AUTHOR]

Freshwater unionid mussels are among the most imperiled fauna in North America, and their decline has been partially attributed to sediment from anthropogenic activities. However, there remains a debate regarding the role played by sediment in mussel declines due to a lack of field and laboratory evidence. If sediment is responsible for mussel declines, then a lack of information will likely impede efforts to mitigate species declines and protect remaining habitat. However, if the impacts of sediment are overstated, time and resources may be wasted on a threat that has little bearing on mussel declines or habitat loss. Given this knowledge gap, the purpose of this paper is to review the literature focused on the potential impact of suspended sediment and sedimentation on freshwater mussels. We focused our search on suspended sediment, expressed either as suspended sediment concentration (SSC) or total suspended solids (TSS), and sediment deposition and scour. We found increases in suspended solids could impact mussels by decreasing food availability, physically interfering with filter feeding and respiration, and impeding various aspects of the mussel–host relationship. We also found mussel–sediment thresholds, wherein certain concentrations of sediment caused significant declines in population performance, which could serve as reference points for ecological research and management. Specifically, we found clearance rates (a measure of feeding) were negatively impacted by TSS concentrations >8 mg/L, and respiratory stress occurred at ∼600 mg/L. Declines in fertilization success and glochidial (i.e., mussel larvae) development were observed at TSS values of 15 mg/L, and reproductive failure occurred at 20 mg/L. Impacts on host fish attachment and glochidial encystment occurred at TSS concentrations of 1250–5000 mg/L. Impacts on fish varied depending on the biological endpoint but typically occurred at TSS values ranging from 20 to 5000 mg/L. We also found mussels were sensitive to smothering and mortality occurred at depths as low as 0.6–2.5 cm of substrate. Finally, we found relative shear stress (RSS) values >1, which is a measure of substrate stability in response to scour and entrainment, resulted in significant declines in mussel biodiversity. [ABSTRACT FROM AUTHOR]

The paper presents the results of a series of laboratory and field model pile tests performed to study the factors controlling the base pressure – settlement reponse of piles in sand. One series of tests involved the installation and load testing of steel open- and closed-ended piles in loose sand contained in a large pile testing chamber. A second series involved tests on open- and closed-ended steel piles and a concrete bored pile at a dense sand test bed site. The experiments were designed to investigate the effects of pile type, sand consistency, and installation resistance on a pile’s base response during static loading. The tests revealed that both the base capacity and stiffness of piles in sand are controlled by the degree of prestress imposed on the soil below the pile tip. Simple expressions, which require the small strain stiffness and cone penetration test data as the input parameters, are developed to predict the base pressure – settlement response. The final part of the paper employs other field tests on full-scale displacement piles and bored piles to verify the validity of the proposed approach. [ABSTRACT FROM AUTHOR]

Efforts to stem global change include the application of new technological developments that aim to reduce atmospheric carbon dioxide (CO2) through the carbon capture and storage (CCS) of this greenhouse gas in stable geological structures. In this paper, we assess the potential risks related to the application of CCS technology and the acidification of aquatic ecosystems through CO2 enrichment. We use the multiple lines of evidence approach (LOEs) to characterize the effects of the acidification with contamination in aquatic sediments. We highlight and discuss the effects of acidification on the LOEs including contamination and mobility of contaminants in sediments, toxicity, macrobenthic community structure, in situ effects, and bioaccumulation–biomagnification processes. We further assess the results of acidification on the toxicity of organic contaminants such as antibiotics or illicit drugs like the freebase form of cocaine (crack). The main goal of using the LOE approach is to distinguish between adverse effects that are associated with contaminants and those related to acidification by enrichment of CO2 as a result of CCS technology. Previous assessments were not designed or conducted to incorporate an integrative point of view, nor did they employ a weight of evidence approach (WOE) in risk characterization and management of CCS operations and other situations related to acidification by enrichment of CO2 in the aquatic ecosystem. Based on the findings of this review, the WOE can identify the effects of the acidification on the different LOEs used for sediment quality: contaminant mobility, the adverse effects in organism under laboratory and field conditions, and the bioaccumulation–biomagnification of contaminants. The main strength in using the WOE is the ability of this method to discriminate between LOE responses associated with contamination by different organic and inorganic substances from those related to CO2 acidification itself. The WOE will significantly improve the risk assessment in areas affected by potential leakages of CO2 during CCS operations. [ABSTRACT FROM AUTHOR]

Over the last 10 years, marine gas hydrate drilling expeditions utilizing advances in pressure coring techniques and imaging have routinely encountered gas hydrates residing in fine-grained sediments. The hydrate typically occurs as fracture-filling, near vertical, veins that displace the sediment, potentially leading to increased sediment strength that may prevent normal consolidation of the sediment thus leading to underconsolidation. Destabilization of this hydrate, through climate change or human activity on the seafloor, may cause dramatic loss of strength of the sediment and pose a significant geohazard. To assess the impact of hydrate veins on sediment behaviour, this paper reports on a series of consolidated (CU) and unconsolidated undrained (UU) triaxial tests carried out on fine-grained soil specimens hosting simplified, vertical, cylindrical tetrahydrofuran (THF) hydrate veins of varying diameters. The results show that increasing hydrate vein diameter significantly increases strength and stiffness, including the development of post-peak strain-softening. The mode of failure of the hydrate veins influenced the specimen strength, but did not affect the specimen stiffness. Hydrate dissolution during CU tests prevented quantitative comparison with UU tests. However, CU test results on the soil specimens containing the largest hydrate vein suggest that increasing lateral confining stresses increase the sediment strength. [ABSTRACT FROM AUTHOR]

The strong tidal currents of the Minas Passage in the Bay of Fundy, Nova Scotia, have made this area an important site for testing and development of tidal power technologies. Understanding sediment processes in this area is essential for determining the impacts that large-scale tidal power extraction would have on the system. Previous estimates of sediment input to the Basin suggest that much more sediment enters the Basin than accumulates within it; therefore, the bottom sediment texture should be in hydrodynamic equilibrium with bottom currents. A recent study, however, showed that sediment texture is generally finer that what was expected based on current speeds. This paper uses geographic information systems methods to provide updated and more highly resolved measurements of the amount of sediment entering the Minas Basin from the dominant source, which is coastal erosion. Volumetric input from coastal erosion is 1.1 × 106 m3·a−1, which is more than two times smaller than previous estimates. This updated value makes input rates comparable to accumulation rates, and agrees with the hypothesis that bottom sediment texture is not in equilibrium with current speeds. Grain-size distributions also support the hypothesis that the Minas Basin acts as a sediment trap. [ABSTRACT FROM AUTHOR]

This paper presents a case history of a geotextile reinforced highway embankment constructed on a soft estuarine deposit installed with prefabricated vertical drains. The case history documents the geotechnical site characterization, embankment construction, and monitoring program. The loading response of the soft estuarine soil was monitored during construction using hydrostatic profile gauges, settlement plates, pneumatic piezometers, and slope inclinometers. Settlements of up to 1.3 m were measured under the 4 m high embankment. The deformation behaviour was interpreted qualitatively from the monitoring data using the general framework of elastic-plastic soil models. The effectiveness of the monitoring program is also briefly discussed. The paper provides performance details that make this case history useful to researchers studying the loading response of soft soils under a geotextile reinforced embankment. [ABSTRACT FROM AUTHOR]

Onshore thermal treatment of offshore drilling mud waste generates a mineral by-product, referred to in this paper as thermally treated drill mud waste (TTDMW). Environmental regulations can result in the generation of significant quantities of this material, and hence it would be beneficial from a sustainability perspective to identify a value-added recycling use for this material. Recycling TTDMW into a primary compacted soil barrier system for municipal solid waste landfills represents one such possible reuse. It is hypothesized that residual amounts of organoclays and organic carbon in the TTDMWs will act as a beneficial sorbent to low levels of volatile organic compounds (VOCs) often found in municipal solid waste leachate. To assess this hypothesis, two different TTDMW materials (from Nova Scotia and the United Kingdom) were subjected to batch and diffusion testing to assess VOC sorption. It is shown that partitioning coefficient (Kd) values obtained from diffusion testing were generally lower than those obtained from batch testing. Contaminant migration modelling of a hypothetical TTDMW barrier system using measured VOC sorption levels is presented in the paper to provide some relevance to the results obtained. [ABSTRACT FROM AUTHOR]

The holotype of Garudimimus brevipes, discovered from the Upper Cretaceous sediments of Mongolia and named by Barsbold in 1981, is redescribed in detail in this paper. Reexamination of the holotype reveals a great deal of anatomical information, which allows us to revise the original diagnosis of this taxon and make comparisons with other ornithomimosaur taxa to understand the evolution of ornithomimosaurs. This paper suggests that characters used to differentiate this taxon in the original paper (short ilia, short metatarsals, exposure of the proximal end of metatarsal III, presence of pedal digit I, and absence of pleurocoels) are not apomorphies but represent the primitive conditions in ornithomimosaurs and are symplesiomorphies. Revised diagnoses are assigned for G. brevipes (posteriorly positioned jaw articulation, fossae at base of dorsal process of supraoccipital, paired depressions on neural spines of proximal caudal vertebra, and deep groove on lateral surface of pedal phalanges III-1 and III-2). Metatarsals of Garudimimus display a non-arctometatarsalian condition as in an Early Cretaceous form, Harpymimus, but the constriction of metatarsal III in Garudimimus is intermediate between Harpymimus and the arctometatarsalian condition in Gallimimus and other derived ornithomimosaurs (ornithomimids). Garudimimus is the only non-ornithomimid ornithomimosaur with edentulous jaws, which were probably covered by rhamphothecae. The loss of teeth with evolution of rhamphothecae and development of a cutting edge in the dentary of Garudimimus suggest the acquisition of feeding habits that included plucking food at the anterior portion of the jaw and cutting at the middle portion, similar to ornithomimids. [ABSTRACT FROM AUTHOR]

This paper investigates the significant curling that occurs when thin soil layers undergo desiccation. Curling deformations, in the form of (1) lifting off from the edges (generating a concave surface), or (2) lifting off from the middle (creating a convex surface), are reported in the drying of soft soil and concrete pavements in the field. This paper presents experimental observations of significant curling of both forms 1 and 2 in wet soil specimens under controlled drying conditions. A theoretical explanation for curling is presented on the basis of unsaturated soil mechanics. The curling was primarily attributed to differential shrinkage strain increments that occur down the soil profile and their variation with the progression of desiccation. Making use of nonlinear elasticity theory under large deformations and measured properties, the shrinkage and curling deformations were modelled using the FLAC (Fast Lagrangian Analysis of Continua) computer program. The modelling approach appears to capture the observed behaviour of curling during desiccation. [ABSTRACT FROM AUTHOR]

The first part of the paper describes the precision and long-term stability that are required in triaxial stress-strain measurements and in stress-path control systems to obtain reliable information on creep in granular media. It is shown that membrane penetration and sample end compliance must be accounted for and that lubricated ends and local strain measurements are essential. The temperature sensitivity of each transducer also needs to be assessed, even when working in a temperature-controlled laboratory. The second part of the paper presents illustrative data that were obtained in tests on sand and Ballotini® glass beads. Considerable creep deformations were observed under both isotropic and anisotropic effective stress conditions, even at relatively low pressures where particle breakage was unlikely to be significant. The experiments show how creep depends on the stress conditions imposed, how the strain increment directions change during creep, and how the creep rates stabilize with time.Key words: sand, creep, triaxial test, yielding, membrane penetration.Cet article décrit en premier lieu la précision et la stabilité à long terme qui sont requises dans les mesures de contraintes-déformations triaxiales, et dans les systèmes à cheminement de contraintes contrôlé, de façon à obtenir des informations fiables sur le fluage dans les milieux granulaires. On montre que l'incrustation de la membrane et le degré de liberté des extrémités des échantillons doivent être pris en considération, et que la lubrification des extrémités et les mesures des déformations locales sont essentielles. La sensibilité à la température de chaque capteur doit être évaluée même lorsque les essais sont réalisés dans un laboratoire à température contrôlée. La seconde partie de l'article présente par illustration les données qui ont été obtenues dans les essais sur du sable et des billes de verre. Des déformations de fluage considérables ont été observées dans des conditions de contraintes effectives tant isotropes qu'anisotropes, même à des pressions relativement basses auxquelles il était peu probable que le broyage des particules soit significatif. Les expériences montrent à quel point le fluage dépend des conditions de contraintes imposées, comment les directions des incréments de déformation changent de direction durant le fluage, et comment les taux de fluage se stabilisent avec le temps.Mots clés : sable, fluage, essai triaxial, limite élastique, incrustation de la membrane.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

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]

This paper presents the preliminary results of experimental research into the stabilization of clayey sediments dredged from the Port of Taranto (Italy) with cement and (or) lime. First, the physical properties of the natural sediments are briefly described and compared with those of the same sediments when treated with different additives and cured up to 4 years. In particular, the effect of the treatment on the soil plasticity properties is originally analyzed in terms of plasticity paths. Then, the influence of the different stabilizing agents on the compression behaviour of the dredged soil is analyzed and methods for quickly predicting the admixed-soil behaviour are presented. [ABSTRACT FROM AUTHOR]

The Frenchman and Ravenscrag formations of southwestern Saskatchewan, Canada, record an apparently continuous sequence of nonmarine clastic sediments across the Cretaceous-Paleogene (K-Pg) boundary. Extensive exposures of these fossil-rich sediments occur in the Frenchman River Valley, near the towns of Ravenscrag, Eastend, and Shaunavon, and have been a focus of study since the 1970s. Despite this long history of investigation, a comprehensive account of the geographic and stratigraphic positions of many of the significant fossil localities has yet to be published. Given this state of affairs, the goals of this paper are to ( i) document the geographic locations, stratigraphic positions, and lithologies of 11 key vertebrate microfossil localities, including several new localities that have been recently discovered, and ( ii) provide an update on the status of these fossil localities, the majority of which have not been sampled in the last 20 years. Four fossil localities are known from the lower Paleocene Ravenscrag Formation, all of which are Puercan in age: Rav W-1 (Pu2), French Fry (Pu1), Croc Pot (?Pu2), and Pine Cree (?Pu2). With the exception of Rav W-1, which has since been lost as a consequence of quarry reclamation, all of the Ravenscrag Formation localities remain accessible and continue to be productive. Seven vertebrate microfossil localities from the upper Maastrichtian Frenchman Formation are reported here, all of which are Lancian in age: Long Fall, Fr-1, By Gar Gap, Hairpin, Wounded Knee, Wounded C, and Gryde. With the exception of Long Fall and Wounded Knee, which have been lost through reclamation or construction, all of the Frenchman Formation localities are accessible and remain productive. [ABSTRACT FROM AUTHOR]

Diffusion of contaminants can play a significant if not dominant role in many applications encountered within the field of environmental geotechnics. The objective of this paper is to provide an overview of the important role diffusion plays in such applications. The presentation proceeds from a historical perspective, beginning with the recognition in the late 1970s to early 1980s that diffusion may be an important process in assessing contaminant migration through low-permeability barriers in waste containment applications. Data from the literature and simplified model simulations are used to illustrate under what conditions diffusion is important, and the significance of diffusion is illustrated with respect to different barrier components and types of barriers used in waste containment applications. The barriers considered include natural clays, compacted clay liners, geomembranes, geosynthetic clay liners, composite liners, vertical cutoff walls, subaqueous caps for contaminated sediments, and highly compacted bentonite buffers for high-level radioactive waste containment. The significance of semi-permeable membrane behavior on liquid-phase diffusion through bentonite-based barriers also is highlighted. The potential importance of matrix diffusion as an attenuation mechanism for contaminant transport is illustrated, and the roles of both liquid-phase and gas-phase diffusion under unsaturated conditions are discussed. Finally, the role of diffusion in terms of remediation applications is illustrated via an example analysis illustrating the impact of reverse matrix or back diffusion on the effectiveness of pump-and-treat remediation, as well as via a summary of several diffusion-based models commonly used to describe the leaching of contaminants from a variety of stabilized-solidified waste forms. [ABSTRACT FROM AUTHOR]

The exposures at the St. Marys Cement Inc. quarry at St. Marys, Ontario, have been studied by geologists since the mid-1950s. This paper summarizes previous and new information collected in 2009, 2010, and 2012 and discusses the record of sediments resting on the bedrock surface that have been exposed during quarry operations. The exposed sediments illustrate the dynamic behavior of the Laurentide Ice Sheet in this area during the Late Wisconsin. Evidence for subglacial meltwater activity, shifting ice-flow directions during till deposition, a local or regional erosion event, possible subaerial exposure, and ice-marginal sedimentation is observed in the sequence of tills and stratified sediments exposed in the quarries. It also highlights how rapid lateral facies changes, complex contact relationships, and steep erosional contacts can prove to be challenging for correlation and extrapolation of subsurface units into three-dimensional stratigraphic models. Fourteen units were identified of which the lower six were deposited during the Nissouri age (Catfish Creek Drift). This included five layers of till deposited by a glacier that alternated from flowing out of the Lake Huron basin to that of a regional flow to the south-southwest. An angular unconformity cuts into these sediments and separates them from a finer-grained sediment sequence (primarily of Port Bruce age) consisting of glaciofluvial gravel, two fine-textured till layers, and rhythmically bedded glaciolacustrine sediments, all overlain by the uppermost till, the Rannoch Till, and Mitchell Moraine ice-marginal fan sediments. [ABSTRACT FROM AUTHOR]

This paper presents results of a passive-source seismic mapping study in the Nechako-Chilcotin plateau of central British Columbia, with the ultimate goal of contributing to assessments of hydrocarbon and mineral potential of the region. For the present study, an array of nine seismic stations was deployed in 2006-2007 to sample a wide area of the Nechako-Chilcotin plateau. The specific goal was to map the thickness of the sediments and volcanic cover, and the overall crustal thickness and structural geometry beneath the study area. This study utilizes recordings of about 40 distant earthquakes from 2006 to 2008 to calculate receiver functions, and constructs S-wave velocity models for each station using the Neighbourhood Algorithm inversion. The surface sediments are found to range in thickness from about 0.8 to 2.7 km, and the underlying volcanic layer from 1.8 to 4.7 km. Both sediments and volcanic cover are thickest in the central portion of the study area. The crustal thickness ranges from 22 to 36 km, with an average crustal thickness of about 30-34 km. A consistent feature observed in this study is a low-velocity zone at the base of the crust. This study complements other recent studies in this area, including active-source seismic studies and magnetotelluric measurements, by providing site-specific images of the crustal structure down to the Moho and detailed constraints on the S-wave velocity structure. [ABSTRACT FROM AUTHOR]

Excess pore-water pressure has a significant effect on submarine slope stability and sediment deformation, and therefore its in situ equilibrium measurement is crucial in carrying out accurate slope stability assessments and accurately deriving geotechnical design parameters. In situ equilibrium pore-water pressure is usually obtained from pore pressure decay during piezocone tests. However, submarine shelves and slopes are often characterized by the existence of low-permeability (fine-grained) sediments involving long dissipation tests that are an important issue for offshore operational costs. Consequently, short-term and (or) partial dissipation tests are usually performed and in situ equilibrium pore-water pressures are predicted from partial measurements. Using a modified cavity expansion approach, this paper aims to predict for four different sites the in situ equilibrium pore-water pressures. Comparisons between predicted and observed in situ equilibrium pore-water pressures allowed the development of a guide to evaluate the minimum time required to perform short-term dissipation tests for a given marine sediment. The main finding of this Note is that the second derivative of the pore pressure, u, versus the logarithm of time, t, ∂2 u/ ∂ln( t)2 must be positive to calculate accurately the in situ equilibrium pore-water pressures from partial measurements. [ABSTRACT FROM AUTHOR]

A giant short-faced bear (Arctodus simus) ulna fragment was found at the base of exposed Quaternary sediments at Cowichan Head, southern Vancouver Island, British Columbia. In this paper, the ulna fragment and its geological context are described and a reasonable taphonomic trajectory is presented. The radiocarbon age of 22 750 ±140 BP on the bone indicates that these bears were on Vancouver Island during the late Wisconsinan. A likely source for the Cowichan Head A. simus was from the mainland to the southeast. [ABSTRACT FROM AUTHOR]

The major rivers within the City of Winnipeg are founded in glacial Lake Agassiz clay and silt sediments that have low shear strength. As such, riverbank instabilities are a common issue along many stretches of the rivers. The use of rockfill columns has become an increasingly utilized approach for stabilizing failing banks. Recent cases in Winnipeg have shown that movements can occur following installation of rockfill columns. Uncertainty regarding the magnitude of these movements that is required to mobilize shearing resistance in the rockfill columns has resulted in situations where the stability of riverbanks following remediation has been questioned. This has provided a need to improve our understanding about how much movement a stabilized slope must undergo before sufficient shear resistance of the rockfill column will be mobilized. The results of experimental testing conducted to assess the shear mobilization of rockfill column materials using a large-scale direct shear test apparatus are presented in this paper. The testing methodology is described along with the test results. The results show that the development of material specifications, construction, and placement methods and appropriate methods of analysis requires understanding of the stress–strain properties of the in situ soil and the rockfill material. [ABSTRACT FROM AUTHOR]

Cryptococcus albidus, isolated from the sediments of Century Pulp and Paper Mill, Lalkuan, Nainital, Uttarakhand, India, produced a copper containing oxidase, laccase, that was capable of degrading environmental pollutants. Bagasse was the most efficient inducer for laccase production. The Taguchi approach was used to optimize the growth media for five factors, i.e., pH, copper sulphate, carbon, nitrogen, and the inducer at four levels using an M-16 orthogonal array. The optimum conditions for laccase production were pH (6), CuSO4 (2 mmol/L), meat peptone (0.5%), glucose (0.1%), and bagasse (1.0%). After optimization, laccase production increased seven times from 32 to 219 IU/mg. The inducer (bagasse) had maximum effect on laccase production leading to 52% increase, while pH had minimum effect with 7% increase. Growth media with laccase activity (2 U/mL) was applied for the bioremediation of dyes, effluent, and chemical compounds. These experiments showed that the growth media with laccase activity (2 U/mL) produced by Cryptococcus albidus had good potential for bioremediation of toxic and recalcitrant compounds. Further, the laccase enzyme extracted from the growth media was fractionated by DEAE-cellulose ion-exchange chromatography, and the molecular weight of the enzyme determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was found to be 64 kDa. The activity of laccase was confirmed by native PAGE, in which ABTS was used for staining gel. [ABSTRACT FROM AUTHOR]

As a part of the settling and self-weight consolidation of fine-grained materials, a common but not widely recognized phenomenon randomly occurs, namely channeling or the formation of narrow vertical paths or “channels.” Channel formation can have important effects on the microstructure, consolidation, and shear strength characteristics of newly formed sediments. However, only a few studies have been performed on channeling. The causes of channel formation and the factors affecting it are still not fully understood. This paper presents the results of an experimental study of channel formation during settling and self-weight consolidation in fine-grained materials. Four types of fine-grained materials and different slurry concentrations were tested using large and small settling columns, and channel formation was observed using a high-resolution digital camera. The results indicate that the primary mechanism for channel formation is the coalescence of small-scale discontinuities between clusters of soil particles formed by flocculation. The stronger the degree of flocculation, the more prevalent is the formation of channels. Pore pressure measurements show the effects of channels in dissipating excess pore pressures in sediments undergoing self-weight consolidation. Faisant partie de la déposition et de la consolidation sous leur poids propre des matériaux à grains fins, un phénomène courant mais pas souvent reconnu se produit de façon aléatoire, qui est la formation de cheminements verticaux étroits ou « canaux ». La formation de canal peut avoir d’importants effets sur les caractéristiques de la microstructure, de la consolidation et de la résistance au cisaillement des sédiments nouvellement formés. Cependant, seulement quelques études ont été réalisées sur la formation de canaux. On ne comprend pas encore complètement les causes de la formation de canaux et les facteurs qui l’influencent. Cet article présente les résultats d’une étude expérimentale de formation de canaux durant la déposition et la consolidation sous leur poids propre dans des matériaux à grains fins. Quatre type de matériaux à grains fins et différentes concentrations de boue ont été mises à l’essai en utilisant de grandes et de petites colonnes de déposition, et la formation de canaux a été observée au moyen d’une caméra digitale à haute définition. Les résultats indiquent que le mécanisme primaire pour la formation de canaux est la coalescence de discontinuités à petite-échelle entre les agglomérats de particules de sol formés par floculation. Plus le degré de floculation est fort, plus la formation de canaux est prévalente. Les mesures de pressions interstitielles montrent les effets des canaux sur la dissipation des pressions dans les sédiments subissant la consolidation sous le poids propre. [ABSTRACT FROM AUTHOR]

While a majority of the studies related to unsaturated soils have focused on volume change, flow, and shear strength behavior, investigations of tensile strength of unsaturated soils, especially granular soils, have not received much attention except for those on cemented and clayey soils. This paper focuses on fundamental studies of tensile strength properties of granular soils in the unsaturated state, which were examined experimentally and theoretically. Experimental studies have shown that it is possible to accurately measure the tensile strength of sands at water contents in the range of 0.5%–17% by means of simple techniques. The method of specimen preparation has proved important, and the use of relatively large specimens has made development of homogeneous specimens and measurements relatively straightforward. The magnitude of the tensile strength of moist and relatively clean sands varies with water content, density, and soil type. The experimental data are also compared with mechanics-based models developed for monosized spheres, and their application for a real granular soil with a variety of particles is discussed in the unsaturated state, which includes the pendular, funicular, and capillary regions. [ABSTRACT FROM AUTHOR]

This is the follow-up paper to Vassallo et al. (2007), which discussed the experimentally observed small-strain behaviour of an unsaturated compacted silt. The influence that suction and, more in general, mean net stress – suction history has on the initial shear stiffness was analysed and ascribed to the accumulation of irreversible volumetric strains. In this study, a model able to predict the observed behaviour is proposed, based on classical unsaturated soil volumetric hardening elastoplastic formulations. Starting from the interpretation of the results relative to simple stress paths, such as preliminary equalization and loading–unloading compression, the results of "complex" stress paths, such as those including drying–wetting cycles, have subsequently been modelled by introducing some additional parameters. [ABSTRACT FROM AUTHOR]

Measurement of the soil-water characteristic curve (SWCC) in the laboratory is commonly conducted under zero confining pressure. However, in the field, the soil is under a confining stress. Therefore, it is important to study the effects of the confining stress on SWCC. In addition, the consolidation curve is normally generated under saturated conditions. However, the soil above the water table is usually unsaturated. Hence, it is also necessary to investigate the effects of matric suction on the characteristics of the consolidation curves. This paper presents the SWCCs under different net confining stresses and the isotropic consolidation curves under different matric suctions that describe the volume change characteristics of unsaturated soils with respect to stress state variables, net normal stress, and matric suction. A series of SWCCs was determined for statically compacted silt specimens in a triaxial cell apparatus under different net confining stresses. Isotropic consolidation tests under different matric suctions were also carried out. The results of the SWCC tests show that the air-entry value increased with increasing net confining stress. The yield points (i.e., yield suction, s0) obtained from the SWCC tests also increased with increasing net confining stress. The results of isotropic consolidation tests indicate the strong influence of matric suction on compressibility and stiffness of the compacted silt specimens. [ABSTRACT FROM AUTHOR]

A new hypoplastic model for clays with meta-stable structure is presented in this paper. A new method for incorporation of structure effects into hypoplastic models based on the modification of barotropy and pyknotropy factors is proposed and applied to an existing hypoplastic model for reconstituted clays. The new model is characterized by a simple calibration procedure and a small number of parameters. This makes the model particularly suitable for practical applications. The model is evaluated using experimental data for two natural soft clays. Thanks to the incrementally nonlinear character of the hypoplastic equation, the proposed model predicts behaviour of overconsolidated clays comparably to advanced kinematic hardening elastoplastic models. [ABSTRACT FROM AUTHOR]

IIn this paper the capability of two different feed-forward back-propagation neural network algorithms, namely Levenberg-Marquardt and gradient-descent, in solving complex nonlinear problems is utilized for suspended sediment prediction. The monthly streamflow and suspended sediment data from two stations, Palu and Çayağzi, in the Firat Basin in Turkey are used as case studies. The first part of the study involves the prediction of sediment data for the two stations. The second part of the study focuses on the prediction of the downstream station sediment data using upstream data. The effect of the periodicity on model performance is also investigated in each application. [ABSTRACT FROM AUTHOR]

The opening or removal of forest canopies during harvesting or land clearing results in a predictable sequence of responses, the descriptions of which appear remarkably similar around the world. Such activities are now widely acknowledged to have adverse impacts upon water quality and in-stream ecology. Sediment delivery, therefore, encapsulates the dominant process by which water resources are impacted and the process that can be best managed to limit off-site impacts. This paper is a review of current processes, and perceptions, of sediment delivery in managed forests. We outline the major components of sediment and runoff delivery as they relate specifically to timber harvesting activities. Whilst much existing research has focused upon soil loss as the major component of timber harvesting impacts, this review highlights both the need for, and benefits from, a conceptual advance in our thinking of sediment delivery. We advocate that by managing runoff delivery pathways and the resultant pattern of hydrological connectivity, we can limit the potential adverse effects of forest harvesting on in-stream water quality. Specific attention is given here to the interaction of the forest road and track network with both sediment and runoff delivery. The result is a comprehensive account of how best to manage timber harvesting for both on-site sustainability and off-site water resource protection.Key words: timber harvesting, sediment delivery, road network, connectivity, best management practices (BMPs). L'ouverture ou l'enlèvement de la canopée, au cours des récoltes ou du défrichement, conduisent à une séquence prévisible de réactions, dont la description semble remarquablement comparable partout au monde. On reconnaît maintenant que de telles activités ont des impacts négatifs sur la qualité de l'eau et l'écologie des cours d'eau. Conséquemment, la déposition des sédiments englobe le processus dominant par lequel les ressources en eau sont affectées et le procédé qui peut le mieux être aménagé, pour limiter les impacts au-delà du site. Les auteurs revoient les processus courants, ainsi que les perceptions, de la déposition des sédiments provenant des forêts aménagées. Ils considèrent les composantes majeures des sédiments et la déposition par les eaux de surface, dans leurs relations spécifiques avec les activités d'exploitation forestière. Bien que les recherches conduites jusqu'ici aient mis l'accent sur la perte de sol, comme la composante majeure des impacts de l'exploitation, cette revue souligne à la fois les besoins et les bénéfices qui peuvent générer un progrès conceptuel, dans notre réflexion sur le dépôt des sédiments. Les auteurs proposent qu'en aménageant les sentiers de flux des sédiments ainsi que le patron de connectivité hydraulique qui s'en suit, on pourrait limiter les effets négatifs potentiels de la récolte forestière, sur la qualité des cours d'eau. On accorde une attention spéciale à l'interaction des chemins forestiers et du réseau de pistes, avec à la fois le flux et le dépôt des sédiments. Ceci conduit à une perception intégrée permettant de mieux aménager la récolte forestière, à la fois pour la durabilité du site, et la protection des ressources en eau, en aval. Mots clés : exploitation forestière, dépôt des sédiments, réseau routier, connectivité, pratiques optimales d'aménagement (BMPs).[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

A paleolimnological study was undertaken to describe the past environment of the St. Mary's River downstream of Lake Superior. Two sediment cores were obtained from the deepest part of Lake George, a fluvial lake in the river system. Rigorous analyses of radionuclides (210Pb, 226Ra, and 137Cs) and chemical properties provided an accurate sediment chronology. More than 450 diatom species from 47 genera were identified. Diatom and geochemical data indicated gradual environmental change in response to anthropogenic activities, including logging, hydrologic manipulation, and steel, leather, and paper industries. A decline in water quality occurred gradually from the late 1800s through the 20th century in response to human activities, as was apparent from an increase in eutrophic–planktonic diatom taxa. A decline in benthic taxa and an increase in contaminant metals were also contemporaneous with impacts during the 20th century. Subfossil diatoms were similar to those recorded in paleolimnological investigations from the Great Lakes. However, diatom profiles indicate that the algal supply from upstream Lake Superior has been minimal and that the cores mainly reflect environmental characteristics of the near-upstream environment. Despite stochastic sedimentary regimes and complex habitats in the lotic system, this study reinforces the value of river paleolimnology at carefully selected sites. [ABSTRACT FROM AUTHOR]

This paper presents a critical-state constitutive model for sands over a wide range of void ratios and consolidation pressures in a triaxial plane. A single set of parameters, including a unique critical-state line reached at large strain, is also used in the model, and differences in behavior in triaxial compression and extension are modeled by accounting for anisotropy at small and medium ranges of strain. The model uses a capped yield surface (YS), which is characterized by its size and shape. Following evidence in past literature, the stress ratio at the peak point of the capped YS of loose sands is approximated by the stress ratio measured at the peak point of their undrained effective stress path. Yielding parameters obtained using this stress ratio are also applied in modeling dense sand behavior and drained loading. These parameters account for the effects of inherent anisotropy, void ratio, and confining pressure on yielding stresses and are readily determined from laboratory tests, but further research is required on their determination from field data. The model accounts for stress-induced and inherent anisotropies, using different parameters, which develop and evolve independently. Emphasis is placed on proper modeling of aspects of loose sand behavior that affect their susceptibility to flow liquefaction. [ABSTRACT FROM AUTHOR]

The paper examines the stress–strain behaviour of densely compacted sand tested at pressures up to 80 MPa in one-dimensional compression and 7.2 MPa confining pressure in triaxial tests. Tests were performed at temperatures up to 100 °C. The testing relates to a proposal by Atomic Energy of Canada Limited to fill containers of waste nuclear fuel with a crushed quartz sand to provide additional stiffness. No significant effects of temperature were encountered in either isotropic compression or triaxial shear. [ABSTRACT FROM AUTHOR]

Composite clay is a mixture of clay, as the main body, and aggregates, which are floating within the clayey matrix. The undrained behavior of composite clay in its natural or compacted state, e.g., core material of embankment dams, has great importance for geotechnical engineers. An extensive test program was conducted on kaolin–gravel and kaolin–sand mixtures to investigate various effects of aggregates on the mechanical behavior of the mixtures during strain-controlled monotonic and cyclic loadings. Monotonic test results reveal that increasing the aggregate content leads to a gradual increase in shear strength. Meanwhile, when the aggregate content is raised, the pore pressure increases for both monotonic and cyclic loading. It is also found that the presence of aggregates within a cohesive matrix leads to formation of a heterogeneous matrix in the clayey part of composite clays. This heterogeneity in turn causes pore pressure to be increased with an increase in the aggregate content during both monotonic and cyclic loading. In addition, test results show that aggregate size does not influence mechanical behavior appreciably. The results of this experimental research program are presented and discussed in this paper. [ABSTRACT FROM AUTHOR]

This paper analyzes the effect of borehole disturbance, caused by installation of pressuremeter probes in clays, on the derived stress–strain curves. Both overpushing- and overcutting-induced disturbances are considered. It is shown that overpushing results in underestimation of the undrained shear resistance. In general, the degree of underestimation cannot be determined. As for overcutting, the derived stress–strain curves are characterized by high peak strengths. The degree of overestimation of the undrained shear strength may reach 100% for the case of a strain-hardening material. Determination of the strain that corresponds to the peak shear strength allows determination of the true stress–strain curve from the expansion test. Analysis of four well-documented case histories serves to illustrate the proposed approach. [ABSTRACT FROM AUTHOR]

Recent archaeological excavations at a deeply stratified site in northwest Calgary, Alberta have uncovered four occupation layers spanning the interval from 8000 to 2000 BP. Depending on the dating one accepts for the Holocene thermal maximum, two or more of these occupations occurred during this interval of aridity. This site thus provides a record of human occupation during the Archaic (Middle Prehistoric I) period in the Calgary area. More importantly, the site occurs in an upland setting, apparently far removed from reliable sources of water and normal environments of deposition. Yet, the cultural deposits occur in sediments which extend 2 m below surface and include five sedimentary units as well as a minimum of three pedogenic units. This paper presents the results of geoarchaeological research on the changing landscape for the site and notes the implications of these changes for the study of Archaic manifestations on the northern Plains. [ABSTRACT FROM AUTHOR]

It is well known that many landslides, which occur every year in the world, are triggered by rainfall. The mechanics of slope movements due to pore pressure changes are not completely understood, however, and thus are the focus of this paper. Both the case of first-time slides and that of landslide reactivation are examined. It is shown that simple models can reproduce the processes of slope failure and may help in predicting slope behaviour. [ABSTRACT FROM AUTHOR]

A 37-m thick layer of stratified clay encountered during a site investigation at Swann's Bridge, near the sea-coast at Limavady, Northern Ireland, is one of the deepest and thickest layers of this type of material recorded in Ireland. A study of the relevant literature and stratigraphic evidence obtained from the site investigation showed that despite being close to the current shoreline, the clay was deposited in a fresh-water glacial lake formed approximately 13,000 BP. The 37-m layer of clay can be divided into two separate zones. The lower zone was deposited as a series of laminated layers of sand, silt, and clay, whereas the upper zone was deposited as a largely homogeneous mixture. A comprehensive series of tests was carried out on carefully selected samples from the full thickness of the deposit. The results obtained from these tests were complex and confusing, particularly the results of tests done on samples from the lower zone. The results of one-dimensional compression tests, unconsolidated undrained triaxial tests, and consolidated undrained triaxial compression tests showed that despite careful sampling, all of the specimens from the lower zone exhibited behaviour similar to that of reconstituted clays. It was immediately clear that the results needed explanation. This paper studies possible causes of the results from tests carried out on the lower Limavady clay. It suggests a possible mechanism based on anisotropic elasticity, yielding, and destructuring that provides an understanding of the observed behaviour. [ABSTRACT FROM AUTHOR]

This paper describes the instability in the foundation of the Caudalosa tailings dam in Peru. The instability threatened collapse of the structure along with the risk of unacceptable contamination of the River Escalera, located immediately downstream of the toe of the dam. At the time of these investigations, large deformations were in progress. The head scarp of the potential slide, located in the stored tailings, had reached a height of 2 m. Visual observations, as well as subsurface investigations, indicated that the instability was due to the presence of soft to medium plastic clay in the foundation. Emergency stabilization was successfully achieved by the construction of large trenches at the downstream toe, allowing the low consistency clay to be removed and backfilled with compacted mine waste rock. Other secondary stabilizing measures that were undertaken are also described.Key words: clay, dam, instability, remediation, stabilization, slide, tailings.L'article décrit l'instabilité de la fondation de la digue de résidus de Caudalosa au Pérou. L'instabilité menaçait de causer la rupture de la structure avec le risque d'une contamination inacceptable de la rivière Escalera localisée immédiatement en aval du pied de la digue. Au moment de ces investigations, de grandes déformations étaient en train de se produire. L'escarpement principal du glissement, localisé dans les stériles entreposés avait atteint une hauteur de 2 m. Des observations visuelles, de même que des investigations du sous-sol ont indiqué que l'instabilité était due à la présence d'argiles molles à moyennement plastiques dans la fondation. Une stabilisation d'urgence a été réalisée avec succès en excavant de grandes tranchées au pied aval pour enlever l'argile de faible consistance et la remplacer par un remblayage de résidus de roc compactés. On décrit également d'autres mesures secondaires de confortement qui ont été appliquées.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The Nakdong River plain is one of the few areas in Korea where soft clays have been deposited. Although many site investigations related to large-scale reclamation works have been carried out over the past 10 years, soil profiles still need to be better characterized. The Pusan clays at this location constitute an interesting topic for researchers both in and outside Korea due to their geological complexity, unusually great thickness, very low overconsolidation (OCR) values, large consolidation settlement, and the effects of artesian pressure. This paper represents the first comprehensive review of Pusan clays and collates extensive existing and new geotechnical data. These data are then analyzed within the frameworks of both classical and new developments in soft clay engineering to address the problems mentioned above.Key words: Pusan, soft clay, intrinsic compression, geotechnical properties.La plaine de la rivière Nakdong est une des quelques régions en Corée où des argiles molles ont été déposées. Quoique plusieurs études aient été réalisées sur le terrain au cours des dix dernières années en relation avec des travaux de réhabilitation à grande échelle, les profils de sols requièrent une meilleure caractérisation. Les argiles de Pusan sur ce site constituent un sujet intéressant pour les chercheurs tant à l'intérieur qu'à l'extérieur de la Corée à cause de leur complexité géologique, de leur épaisseur exceptionnellement grande, de leur très faible valeur de surconsolidation (OCR), du grand tassement en consolidation, et des effets de pression artésienne. L'article présente la première revue d'ensemble des argiles de Pusan, et collige de nombreuses données géotechniques existantes et nouvelles. Ces données sont alors analysées dans le cadre des développements tant classiques que nouveaux de la construction sur les argiles molles pour traiter les problèmes mentionnés ci-haut.Mots clés : Pusan, argile molle, compression intrinsèque, propriétés géotechniques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The undrained shear behavior of soils with progress of shear displacement is essential to the understanding of liquefied slope failures with long travel distance. In this paper, using a newly developed ring shear apparatus, a series of ring-shear tests were conducted on a silty sand to examine the undrained behavior of sand subjected to long shear displacement. Based on the test results, the undrained shear behavior of sands with a wide range of densities is discussed. A very low effective stress corresponding to liquefaction was observed at the steady state in all of the tests on loose, medium, as well as dense sand. The effects of stress state and shear history on the undrained shear behavior were examined by performing tests on a sample with different initial stress states and shearing the same specimen repeatedly (three times) at each initial stress state. The tests at different initial stress states proved that the initial stress state has an influence on static liquefaction resistance but has no effect on the steady-state shear strength. Repeated shear tests on the same specimen showed that with increasing shear times, both the peak shear strength and the steady-state shear strength for each specimen became greater. Detailed examination of the shear deformation revealed that the liquefaction phenomena in ring shear tests are localized in the shear zone, irrespective of the initial state of the sand. Grain crushing within the shear zone was examined. Finally, it was found that there was an optimal density at which the undrained brittleness index had a minimum value; meanwhile, the undrained brittleness index became greater with increasing initial normal and shear stresses, but decreased with shear times. These findings offer some basic understanding in assessing the postfailure mobility in landslides.Key words: excess pore pressure, localized liquefaction, shear resistance, ring-shear tests, grain crushing, silty sands.Le comportement en cisaillement non drainé des sols durant la progression du déplacement en cisaillement est essentiel pour comprendre ces ruptures de pente par liquéfaction avec un long parcours. Dans cet article, au moyen d'un appareil de cisaillement annulaire circulaire nouvellement développé, on a conduit une série d'essais de cisaillement annulaire sur un sable silteux pour examiner le comportement non drainé du sable assujetti à un grand déplacement en cisaillement. En se basant sur ces résultats d'essais, on discute le comportement en cisaillement non drainé du sable pour une large plage de densités. On a observé une très faible contrainte effective correspondant à la liquéfaction à l'état d'écoulement permanent dans tous les essais sur le sable lâche, moyennement lâche, de même que dense. Les effets de l'état de contrainte et de l'histoire du cisaillement sur le comportement en cisaillement non drainé ont été examinés en exécutant des essais sur l'échantillon avec différents états initiaux de contraintes et en cisaillant le même spécimen à répétition à chaque état de contraintes initiales (trois fois). Les essais à des états de contraintes différents a prouvé que l'état de contrainte initial avait une influence sur la résistance à la liquéfaction statique, mais n'avait aucun effet sur la résistance au cisaillement à l'état d'écoulement permanent. Les essais de cisaillement répétés sur le même spécimen a montré qu'avec des temps de cisaillement croissants, la résistance au cisaillement au pic et la résistance au cisaillement à l'état d'écoulement permanent ont toutes deux été plus grandes pour chacun des spécimens. Un examen détaillé de la déformation en cisaillement a révélé que les phénomènes de liquéfaction dans les essais de cisaillement annulaire rotatif sont localisés dans la zone de cisaillement, sans relation avec l'état initial du sable. Le broyage des grains à l'intérieur de la zone de cisaillement a été examiné. Finalement, on a trouvé qu'il y avait une densité optimale à laquelle l'indice de fragilité non drainé avait une valeur minimale, et que par ailleurs, l'indice de fragilité non drainé devenait plus grand avec l'accroissement des contraintes normales et de cisaillement initiales, mais diminuait avec les temps de cisaillement. Ces constatations offrent une certaine compréhension de base pour évaluer la mobilité post-rupture dans les glissements.Mots clés : excès de pression interstitielle, liquéfaction localisée, résistance au cisaillement, essais de cisaillement annulaire rotatif, broyage des grains, sables silteux.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

This paper presents a method to obtain the constitutive relationships of sand from drained self-boring pressuremeter tests. Plane-strain conditions and Rowe's stress–dilatancy theory are assumed to hold to determine stress and finite strain distributions and paths. The proposed method, which has been validated using both calibration chamber studies and field tests, appears to correctly render the response behaviour of relatively loose to dense sands.Key words: stress–strain relations, self-boring pressuremeter tests, sands, finite strains, stress distributions, paths.Cet article présente une méthode qui permet d'obtenir les relations constitutives des sols à partir d'essais pressiométriques drainés. Des conditions de déformation plane et la théorie de la dilatance de Rowe sont assumées être valides afin de déterminer les distributions de contraintes et de déformations finies, ainsi que leurs cheminements. La méthode proposée, qui a été validée à l'aide d'essais de calibration en cuve et sur place, semble reproduire correctement le comportement des sables lâches et denses.Mots clés : relations contrainte–déformation, essais pressiométriques autoforeurs, sables, déformations finies, distributions de contraintes, cheminements. [ABSTRACT FROM AUTHOR]

A parcel of land just south of Ottawa at Gloucester has been the site of an unusual amount of geotechnical research over the past 45 years. The parcel was recently to have been placed on the open real estate market but has been saved for scientific purposes and is now designated as "Canadian Geotechnical Research Site No. 1 at Gloucester". This paper presents an outline of the research that has been conducted at the site, in four general divisions, namely compressibility, strength, deformation, and soil property improvement. It is hoped that the site will stimulate the development and evaluation of new tools and techniques, foster scientific cooperation and information exchange, and allow the results of research involving the site to improve the state of practice, education, and research.Key words: sensitive clay, compressibility research, strength research, deformation research, soil improvement research.Un montant exceptionnel de recherche en géotechnique a été faite durant les 45 dernières années sur un morceau de terrain juste au sud d'Ottawa à Gloucester. Ce terrain devait jusqu'à récemment être vendu mais il a été sauvegardé à des fins scientifiques et est maintenant connu sous le nom « Site No. 1 de recherche canadienne en géotechnique à Gloucester ». Cet article présente les grandes lignes de la recherche effectuée, en quatre divisions générales, soit la compressibilité, la résistance, la déformation et l'amélioration des propriétés des sols. Il y a bon espoir que ce site va stimuler le développement et l'évaluation de nouveaux outils et techniques, entretenir une coopération scientifique et un échange d'information, et permettre à améliorer l'état de la pratique, l'éducation ainsi que la recherche avec les résultats obtenus à même les essais effectués sur le site.Mots clés : argile sensible, recherche sur la compressibilité, recherche sur la résistance, recherche sur la déformation, recherche sur l'amélioration des propriétés des sols. [ABSTRACT FROM AUTHOR]