bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the observational method to hydraulic fill reclamation projects
Authors: Choa V. 
Published: October 2009

This Paper describes the reclamation works at Changi Airport, Singapore, and the associated soil improvement works. Further reclamation work being carried out for future expansion of the airport is also described. Over 2000 ha is being reclaimed using about 200 x 106 m3 of sand. The observational method has been applied to control the execution of the projects. Soil instrumentation has been used to control staged construction of the hydraulic fill, the coastal protection works and soil improvement of the vertical drains. Monitoring systems and site procedures to enact contingency plans are discussed. A trial using dredged clay as a reclamation material is described and the Tianjin Port East Pier project in China is used to illustrate the observational method for the construction of a retaining structure founded on soil improved by deep cement mixing. The Paper also discusses the vacuum preloading method used in combination with vertical drains to improve the hydraulically placed silty clay reclamation in Tianjin L'article présente les travaux d'amélioration des sols et les essais associés réalisés actuellement sur l'aéroport de Changi, Singapour. Il décrit également les travaux qui devront être menés pour une extension future de l'aéroport. Plus de 2000 ha ont été traités à l'aide d'environ 200.106 m3 de sable. Des méthodes d'observation ont été mises en oeuvre pour suivre l'exécution des projets. L'instrumentation du sol a permis à la fois de contrôler les différentes étapes de la mise en place du remblai hydraulique et des travaux de protection côtière, et de tester le drainage vertical du sol. On s'intéresse également aux systèmes d'enregistrement et aux procédures in-situ de déclenchement des plans d'urgence. Un essai utilisant de l'argile de dragage comme matériau de traitement est décrit. Le projet du port East Pier de Tianjin, Chine, permet d'illustrer les méthodes de suivi utilisées lors de la construction d'un ouvrage de soute nement fondé sur un sol injecté par un mélange de ciments. L'article décrit également la méthode de préchargement par vide utilisée en complément des drains verticaux pour étudier le comportement de l'argile silteuse, mise en place hydrauliquement, utilisée à Tianjin comme matériau de traitement.
Knowledge-based systems in geotechnical engineering
Authors: Moula M. , Toll D.G. , Vaptimas N. 
Published: October 2009

The Paper reviews knowledge-based systems which have been developed for geotechnical applications and the geotechnical aspects of the systems are described. Systems have been developed for, among other topics, site characterization, foundations, earth-retaining structures, slope stability, tunnels, groundwater problems and ground improvement. An assessment has been made of the stage of the development of each system (where possible) and also the source of the knowledge incorporated in the systems. L'article passe en revue les différents systèmes empiriques qui ont été développés en vue d'applications géotechniques et décrit les aspects géotechniques de ces systémes. De nombreux sujets sont concernés, par exemple: la caractérisation des sites, les fondations, les souténements, la stabilité des pentes, les tunnels, les eaux souterraines et l'amélioration des sols. Une estimation a été réalisée, dans la mesure du possible, du développement de chacun des systémes ainsi que de son origine.
Geotechnical materials and the critical state
Authors: Novello E.A. , Johnston L.W. 
Published: October 2009

Comparison is made between the triaxial compres-sion behaviour of soil, soft rock and hard rock. On the basis of the evidence, it is argued that the brittle and ductile fields of rock behaviour can be interpreted with reference to the critical state framework originally developed for soils. Within this framework, the brittle—ductile transition in rock is the equivalent to the change in overconsolidated to normally consolidated behaviour found in soils. The critical states for soils and soft rocks represent the frictional plasticity of porous materials, whereas the equivalent critical state for hard rocks is heavily influenced by the cohesive plasticity present in mineral solids. A view of geotechnical materials emerges to emphasize the simiarity of soil and rock behaviour. This suggests that the critical state concept has application to all geotechnical materials. L'article établit une comparaison entre le comportement en compression triaxiale d'un sol, d'une roche tendre et d'une roche duve. Au vu des résul;tats, it semble que le comportement d'une roche dans le domaine ductile et dans le domaine fragile peut s'interpréter en faisant reférence aux modéles à l'état critique développés a l'origine uniquement pour les sols. Dans ces modéles, la transition ductilefragile des roches devient équivalente a la transition surconsolidénormalement consolidé des sols. L'état critique d'un sol ou d'une roche tendre peut étre assimilé à la plasticité de frottement des matériaux poreux alors que l'état critique d'une roche duve dépend fortement de la plasticité de cohésion des minéraux. L'étude de difrerents materiaux géotechniques apporte confirmation de la similitude de comportement existant entre un sol et une roche. Ceci laisse à supposer que le concept d'état critique peut s'appliquer é tous les matériaux géotechniques.
Interpretation of a footing load test on a saprolitic soil from granite
Authors: Da Fonseca A. Viana , Fernandes M. Matos , Cardoso A. Silva 
Published: October 2009

In the north-western region of Portugal residual soils from granite are dominant. Their porous cemented structure leads to a complex geotechnical behaviour, quite distinct from that of transported soils with a similar grain size distribution. The paper describes some of the studies carried out at an experimental site on which a fairly homogeneous saprolitic soil 6m thick was encountered. These studies included: (i) a full-scale load test of a circular concrete footing (1·20m diameter), under carefully controlled conditions and with extensive monitoring; (ii) in situ testing techniques (SPT, CPT, SBPT, CH) and (iii) laboratory testing on high-quality block samples, including triaxial tests with local strain measurement. The discussion is concentrated on the interpretation of the pressure—settlement curve from the footing load test, for a range of pressures typical of working conditions, by means of linear and non-linear elastic analyses based on stiffnesses from the laboratory and in situ tests. Some practical conclusions are extracted regarding the use of in situ and laboratory test results in analytical and empirical or semi-empirical methods for settlement estimation on these residual soils. Les sols résiduels du granit dominent le littoral de la région nord du Portugal. Les fabrique et structure de ces sols et particullièrement leur matrice cémentée et poreuse conduissent à des comportements géotechniques complexes, trés diff6rents des sols transportés avec granulomé trie similaire. Varticle décrit une partie des études réalisé sur un terrain expérimental où apparaissent des niveaux superficiels typiques des sols saprolitiques du granit de la région. Les études réalis6s comprennent: (i) un essai de charge d'une semelle circulaire de béton armé (avec 1·20 m de diamètre), soigneuse et extensivement instrumentée; (ii) diverses essais in situ (SPT, CPT, SBPT, CH); (iii) essais en laboratoire sur des échantillons de haute qualité retirés des blocks taillés en pmts, comprennant des essais triaxiaux avec instrumentation interne des déformations. La discussion est concentrée dans l'interpr6tation de la courbe de chargement-tassement obtenu de Pessai de charge de la semelle en utilisant des résultats des essais in situ et en laboratoire, considérant les niveaux de charge typiques des conditions de service. On extrait des conclusions sur ľapplication des résultats des essais in situ et en laboratoire aux méthodes empiriques et semi-empiriques pour ľvaluation des tassements des fondations en sols résiduels du granit.
Finite element analysis of the Nerlerk underwater berm failures
Authors: Hicks M. A. , Boughrarou R. 
Published: October 2009

Finite element analyses have been carried out to investigate the possible causes of failure, during construction, of the Nerlerk underwater berm– a hydraulically placed sand slope, designed to form part of a bottom-founded offshore oil exploration platform at Nerlerk in the Canadian Beaufort Sea. The double-hardening Monot constitutive law has been used for modelling the fill materials, while an elastic–perfectly plastic von Mises idealization has been used for modelling the weak underlying clay layer, on which the structure was founded. The computed results demonstrate that, for conditions of rapid loading, there are three possible failure mechanisms, depending on the shear strength of the clay. All mechanisms result in liquefaction of the Nerlerk fill and are hence consistent with the flat post-failure slopes observed on site. However, the most likely cause of failure seems to be that of limited movements in the clay layer triggering liquefaction in the Nerlerk fill near to the berm crest. This investigation represents a major step forward over previously published back-analyses, in that no prior assumptions regarding failure mechanism have been involved. It is also a significant improvement over conventional slope stability calculations, which, for liquefiable soils, tend to greatly overestimate on-site factors of safety. Des analyses des éléments finis ont étéeffectuées pour examiner les causes possibles de la rupture, en cours de construction, de la berme submergée Nerlerk–un talus en sable remblayé hydrauliquement, qui devait faire partie ďune plate-forme de prospecdon pétroliére sous-marine á Nerlerk, dans la mer de Beaufort, au Canada. La loi constitutive du double durcissement Monot a servi á modéliser les matériaux de remblai, tandis qu’une idéalisation élastique parfaitement plastique de von Mises a servi á mod6liser la couche sous-jacente &coron;argile faible sur laquelle reposait &coron;ouvrage. Les résultats calculés montrent que, dans des conditions de charge rapide, il existe trois mécanismes possibles de rupture, en fonction de la résistance au cisaillement de &coron;argile. Tous ces mécanismes aboutissent á la liquéfaction du remblai de Nerlerk et sont donc compatibles avec les talus plats observés sur place aprés la rupture. Toutefois, la cause la plus probable de la rupture semble Être celle des mouvements limités dans la couche &coron;argile, qui ont provoqué la liquéfaction du remblai prés du sommet de la berme. Cette étude constitue un grand pas en avant par rapport aux rétroanalyses déjá publiées, en ce sens qu’lle ne part &coron;aucune hypothése quant au mécanisme de rupture. Par ailleurs, elle offre bien plus que les calculs classiques de la stabilité des talus, qui, dans le cas des sols liquéfiables, tendent á surestimer considérablement les coefficients de sécurité sur le terrain.
Ground deformations and stress redistribution due to a reduction in volume of zones of soil at depth
Authors: Skinner H. D. , Charles J. A. , Watts K. S. 
Published: October 2009

The ground deformations and stress redistribution resulting from collapse compression in discrete zones of highly collapsible fill located at different depths within fill with little or no collapse potential has been investigated in the 4-m-deep BRE large test pit facility. The moisture contents and densities of the colliery spoil fill which was used in the test were selected to ensure that, as well as high collapse potential, the zones of dry fill had lower compressibility than the surrounding wetter fill. During fill placement, significant stress transfer occurred, resulting in the measured vertical stresses in the zones being much higher than the stresses in the bulk of the fill. As the fill was inundated by a rising water level, collapse compression occurred in the dry zones and the stress transfer was reversed, with stresses in the zones reducing to very low values. The collapse compression in all the zones was of similar magnitude but the measured surface settlements were dependent on the depth of the zone. The test was modelled using the Sage–Crisp finite element package together with a simple procedure for simulating collapse compression. The observed behaviour was replicated with sufficient accuracy for the numerical procedure to form a means of estimating behaviour with zones of fill of different geometries and located at different depths. Nous étudions les déformations de sol et la redistribution des contraintes provoquées par la compression d'affaissement dans certaines zones d'une décharge extrêmement sujette aux effondrements, situées à différentes profondeurs avec pen on pas de potentiel d'effondrement dans une fosse d'essai BRE de 4 m de profondeur. Le contenu humide et les densiés des déchets miners qui ont été utilisés dans cet essai ont été choisis de fagon à ce que, en même temps que le fort potentiel d'affaissement, les zones de décharge sèches aient une compressibilité inférieure à celle des zones environnantes plus humides. Pendant la mise en place des déchets, un transfert de contraintes significatif s'est pro-duit, rendant les contraintes verticales mesurées dans ces zones bien plus hautes que les contraintes dans le reste de la décharge. Comme la décharge a été inondée en raison de la monée du niveau des eaux, la compression d'affaissement s'est produite dans les zones séches et le transfert de contraintes s'est inversé, les contraintes dans ces zones devenant triès faibles. IL est apparu que la compression d'affaissement était de magnitude similaire dans toutes les zones mais les dépôts de surface dépendaient de la profondeur de la zone. L'essai a été mis en maquette en utilisant le logiciel d'é1éments finis Sage–Crisp avec une procédure simple pour simuler la compression d'affaissement. Le comportement observé a été reproduit avec suffisamment d'exacdtude pour que la procédure numérique forme un moyen d'évaluer le comportement dans des zones de décharge de géométries et de profondeurs différentes.
A conceptual model for the yielding and consolidation of clays
Authors: Houlsby G. T. , Sharma R. S. 
Published: October 2009

A simple micromechanical model is used to derive the shapes of yield surfaces for clays. The simplest version of the model contains features that are similar to the behaviour of clays, and in particular it is able to predict the shape of anisotropic yield surfaces due to K0 consolidation, and their evolution with subsequent straining. The model predicts, however, unrealistic values of certain parameters. A more sophisticated model is derived using similar concepts, so that the derived parameters are realistic, and also so that the model is compatible with the concept of critical state. Un simple modèle micromécanique est utilisé pour déduire les formes des surfaces d'écoulement des argiles. La version la plus simple du modèle contient des caractérisdques qui sont similaires au comportement des argiles, et notamment, elle est capable de prédire la forme des surfaces d'écoulement anisotropes dues à une consolidation K0 et leur évolution à l'effort ult´rieur. Cependant, le modèle prévoit des valeurs non réalistes pour certains paramètres. Un modèle plus sophistiqué est dérivé en utilisant des concepts similaires afin que les paramètres dérivés soient réalistes et que le modèle soit compatible avec le concept d'état critique.
Creep of Concrete in Compression During Drying and Wetting
Authors: Gamble B. R. , Parrott L. J. 
Published: October 2009

SYNOPSIS The paper describes a study of concrete creep during drying-and-wetting regimes. Damp specimens were loaded at ages of 7 or 140 days and drying began at intervals thereafter. Drying creep was observed; its rate of development was linearly related to that of concurrent shrinkage. The correlation was independent of age at loading and of delay in drying, and only mildly dependent upon stress. For different concretes, drying creep can be closely predicted from water/cement ratio or 28 day strength. The creep recoveries of drying specimens were greater than those of damp specimens; drying creep was recoverable to the same extent as basic creep. No additional recovery of drying creep was observed upon rewetting unloaded specimens. Specimens rewetted under load exhibited wetting creep which was linearly related to concurrent swelling. Reference is made to the calculation in practice of strains in concrete subjected to stress and varying humidity. The nature of drying creep is discussed briefly.
Ultrasonic wave velocities in concrete
Authors: Reynolds W. N. , Wilkinson S. J. , Spooner* D. C. 
Published: October 2009

SYNOPSIS The elastic constants of wet and dry concrete specimens of known composition have been calculated from those of cement paste, water and two types of aggregate by using a theoretical model due to Boucher. The densities were also calculated and the velocities of three types of ultrasonic wave were obtained. It has been shown that the calculated velocities are in satisfactory agreement with those measured on some typical concretes. The suitability of gamma radiometry as a measure of density was also assessed by the measurement of mass absorption coefficients on all the materials involved using a 137 Cs source of energy 667 keV.
Fracture toughness measurements of polymer concretes
Authors: Cook D. J. , Crookham G. D. 
Published: October 2009

SYNOPSIS This paper describes the use of linear elastic fracture mechanics to examine the behaviour of premix and impregnated polymer concretes. Results are given for three monomers, viz. styrene, methyl methacrylate and butyl methacrylate, and two strengths of concrete, as well as for appropriate control series. The notched-beam technique is used to determine fracture parameters, together with compliance measurements to determine slow crack growth. Experimental results indicate that thermal treatment to polymerize the monomer in the premix concrete has a marked influence upon fracture toughness. Irradiation on the other hand has little influence. Polymer impregnation increases the stress-intensity factor and the strain at failure, the latter increase being influenced by the extensibility of the polymer. The results also show that the plain and the premix polymer concretes are partially notch-sensitive, whereas the impregnated polymer concrete is a notch-sensitive material.
A study of transitional thermal creep in hardened cement paste
Authors: Parrott L. J. 
Published: October 2009

Synopsis Creep measurements on hardened cement paste subject to various temperaturehistories are described. It wasfound that, when loaded prisms were gradually heated from 2O° to 60°C, creep increased substantially. This transitional thermal creep was pronounced for virgin heating, but was also present to a lesser extent during a second heating to 60°C. Delays in loading and heating generally led to smaller creep strains, and cooling did not induce any transitional thermal creep.
Developments in the variable-stiffness approach to reinforced concrete column design
Authors: Wood R. H. , Shaw M. R. 
Published: October 2009

Synopsis Exceptionally accurate results were recently obtained by Butler, by a new simplified method of design of restrained reinforced concrete columns which was basically an intuitive combination of the variable-stiffness approach developed for steel columns (by Wood) and graphical construction (due to Roik) employing ultimate moment charts. Here an attempt is made to eliminate the graphical construction and to substitute an alternative arithmetical rational procedure, which should be more amenable for development for a code of practice.
A mathematical description of the strength properties of concrete under generalized stress
Authors: Kotsovos Michael D. 
Published: October 2009

Synopsis A mathematical description of the ultimate strength envelope of concrete under axisymmetric stress states has been derived by analysing experimental data obtained in previous investigations of the Concrete Materials Research Group at Imperial College. The derived equations, when combined with an proposed elsewhere for the description of the effect of the intermediate stress σ2 upon the ultimate strength level, define a surface in stress space which provides a simple mathematical representation of the ultimate strength of concrete under generalized short-term loading conditions. The resulting ultimate strength surface conforms with generally accepted shape requirements and has been found to provide a close fit for most biaxial and triaxial strength data published to date.
Effect of sulphate content of cement upon heat evolution and slump loss of concretes containing high-range water-reducers (superplasticizers)
Authors: Khalil S. M. , Ward M. A. 
Published: October 2009

Synopsis At normal temperatures (25°C), concretes containing superplasticizers lose much of their initial high workability within approximately 45 minutes from initial mixing. When the concrete is hot (40°C), the effect is more severe with significant workability (slump) loss occurring within 30 minutes. In this study, the optimum range of SO3, contents for an ordinary Portland cement, with and without superplasticizer addition, has been determined at these two temperatures by using a conduction calorimeter and Lerch's criteria for optimum SO3 content. Concretes were manufactured at both temperatures using cements with the as received and modified SO3 contents, identified in the calorimeter study. It is concluded that there is an optimum range of SO3 content for which workability loss is minimized for concretes containing the superplasticizer, both at the normal and at the elevated temperature. In addition, short- and long-term strengths are improved.
Effect of in-source variability of pulverized-fuel ash upon the strength of OPC/pfa concrete
Authors: Dhir Ravindra K. , Arun G. Aptet , Munday John G. L. 
Published: October 2009

Synopsis The paper describes an investigation into the effect upon the strength of OPC/pfa concrete of the variability of pulverized-fuel ashes from single sources over a period of time. Twenty weekly samples of four ashes were used to make OPC/pfa concretes at three nominal strengths which were then cured under five different conditions. The strength variations caused by the pulverized-fuel ashes were compared with those caused in OPC concretes by an equal number of weekly cement samples. Although variability in ash properties was observed, only one ash exhibited a significantly greater variation in concrete strength than was shown by the cement. Correlations between ash properties and OPC/pfa concrete strengths did not reveal any property which could by itself reliably give any more than a general indication of the probable effect of a batch of pulverized-fuel ash upon OPC/pfa concrete strength.
Shrinkage of oil-soaked concrete
Authors: Matti M. A. , Watson A. J. 
Published: October 2009

Synopsis This paper describes an investigation into the shrinkage of concrete in direct contact with crude oil. The shrinkage or volume change was studied by using 100 × 100 × 500 mm concrete prisms. Ordinary Portland cement, natural river aggregates, four water/cement ratios, and four curing regimes were used. Similar specimens were cast and continuously kept in water and in a constant temperature and humidity room for comparative purposes.