bluuebunny/crossref_metadata_2025 huggingface dataset:
Hull wastewater flow transfer tunnel: recovery of tunnel collapse by ground freezing
Authors: Brown D. A.
Published: November 2009

The Hull Urban Wastewater Treatment Directive (UWWTD) Flow Transfer Works Contract commenced in January 1998. The scheme required the construction of 10·5 km of 3·6 m internal diameter segmental tunnel alongside the north bank of the Humber estuary between West Hull Pumping Station and a new outfall at Saltend to the east of the city. Completion was programmed for November 2000. In November 1999 the works were ahead of programme and progressing well. However, while tunnelling between shaft T3 on the east side of Hull Marina and shaft T2, some 1146 m to the west, on the opposite side of the marina, a 100 m section of the new tunnel collapsed. Following a four-month period for investigation and review, a recovery scheme was agreed and works commenced in March 2000. This report describes the design of the chosen recovery option and the use of ground freezing with liquid nitrogen to provide a stable environment in which to rebuild the tunnel.
Reuse of construction waste: performance under repeated loading
Authors: Sivakumar V. , McKinley J. D. , Ferguson D.
Published: November 2009

The use of recycled aggregates has increased greatly over the last decade owing to enhanced environmental sensitivities. The level of performance required by such materials is dependent upon the applications for which they are used. Many recycled construction wastes have adequate shear strength in relation to various geotechnical applications. However, a possible drawback of these materials is the risk of crushing during repeated loading. The work reported in this paper examined two waste materials: crushed concrete and building debris, both regarded as construction wastes. Tests were also performed on traditionally used crushed rock, in this case basalt. The materials were subjected to repeated loading in a large direct shear apparatus. The amount of crushing was quantified by performing particle size analysis of the tested material. The results have shown that both recycled construction wastes were susceptible to particle crushing. The amount of crushing was influenced by both the vertical pressure and the number of loading cycles. This leads to a marked decrease in peak friction angle.
Modelling vibrated stone columns in soft clay
Authors: McKelvey D. , Sivakumar V. , Bell A. , Graham J.
Published: November 2009

The vibrated stone column technique is an economical and environmentally friendly process that treats weak ground to enable it to withstand low to moderate loading conditions. The performance of the treated ground depends on various parameters such as the strengths of the in-situ and backfill materials, and the spacing, length and diameter of the columns. In practice, vibrated stone columns are frequently used for settlement control. Studies have shown that columns can fail by bulging, bending, punching or shearing. These failure mechanisms are examined in this paper. The study involved a series of laboratory model tests on a consolidated clay bed. The tests were carried out using two different materials: (a) transparent material with ‘clay like’ properties, and (b) speswhite kaolin. The tests on the transparent material have, probably for the first time, permitted visual examination of deforming granular columns during loading. They have shown that bulging was significant in long columns, whereas punching was prominent in shorter columns. The presence of the columns also greatly improved the load-carrying capacity of the soft clay bed. However, columns longer than about six times their diameter did not lead to further increases in the load-carrying capacity. This suggests that there is an optimum column length for a given arrangement of stone columns beneath a rigid footing.
Design and construction of a deep shaft for Crossrail
Authors: Morrison P. R. J. , McNamara A. M. , Roberts T. O. L.
Published: November 2009

An 8·2m diameter, 40m deep shaft for Crossrail is being constructed below the 10m deep basement of the Moorhouse development near Moorgate in the City of London. The depth of the shaft is such that it will penetrate through stiff London Clay and will be founded at the bottom of the Lambeth Group. The shaft is being constructed after the Moorhouse structure has been completed and the design of the Moorhouse foundations places tight constraints on acceptable ground movements due to construction of the shaft. Furthermore, the shaft needs to be designed to accommodate future ground movements associated with construction of Crossrail. The paper describes the complex relationship between the foundations of Moorhouse, the draught relief shaft and the future Crossrail assets. The optimised design includes extensive slip coating and base grouting of the Moorhouse piles, a complex temporary works dewatering system around the shaft and the option to carry out additional dewatering from within the shaft during construction. Control of ground movements through the Lambeth Group was perceived to be a particular problem in relationship to destressing the ground around the Moorhouse piles. To prevent longterm settlement of these piles, provision was made for radial grouting to “restress” the ground should the need arise.
Role of pore water pressures in embankment stability
Authors: Ridley A. , McGinnity B. , Vaughan P.
Published: November 2009

This paper discusses the relationship between climate, in the form of soil moisture deficit, the presence of trees and pore water pressures in railway embankments. The pore water pressure criteria used in the assessment of slope stability by London Underground Ltd are presented and examined in the light of data gathered during the particularly wet winter of 2000–2001. This unusually persistent wet period caused the pore water pressures in some embankments on the London Underground network to increase to unprecedented levels. The results indicated that in some instances the reduction in pore water pressure that tall deciduous trees were assumed to provide could not be relied upon.
The use of jacked-box tunnelling under a live motorway
Authors: Allenby D. , Ropkins J. W. T.
Published: November 2009

Jacked-box tunnelling is a non-invasive technique for constructing a new underpass, culvert or subway beneath existing infrastructure, such as highways and railways. It was used for the first time under a live motorway in the United Kingdom at junction 15A, on the MI motorway, when a vehicular underpass 14 m wide and 8·2 m high by 45 m long was installed with 1·6 m minimum cover to the motorway. The paper describes the technique, and how it was applied in the design and construction of this innovative project. Particular attention is given to the ground movement control measures adopted, which made it possible to safely install a large monolithic box structure at shallow depth beneath the motorway without impeding motorway traffic.
A new explosive method for soil improvement
Authors: Yan S. W. , Chu J.
Published: November 2009

A highway was constructed in Jiangxi Province, China, through a mountainous area. Some sections of the highway went through valleys where a soft clay layer 6–8·5 m deep was encountered. A new explosive method was developed and adopted for this project. The method uses the energy of the explosion to remove the soft clay and replace it with crushed stones. Explosive charges are placed in the soil to be improved according to a specific pattern. Crushed stones are piled up next to the area where the charges are installed. The explosion creates cavities in the soil and causes the pile of crushed stones to slide into the exploded area. The detail of the method and its application to the highway project are described. The effectiveness of the method is evaluated using borehole exploration, plate load tests and groundprobing radar tests.
Pile-settlement evaluation using field stiffness non-linearity
Authors: Berardi R. , Bovolenta R.
Published: November 2009

Understanding the principal features of soil stiffness has been one of the major achievements of geotechnical engineering over the past 30 years. The study of modulus degradation is now one of the main research areas. Understanding non-linearity is essential in foundation design for accurate and reliable evaluation of ground movements. This paper looks at the problem of assessing of deep foundation settlements and describes two approaches developed to enable designers to take soil–foundation non-linear behaviour into account. The first provides in-field stiffness parameters evaluated by back-analysis of full-scale piles. The second involves deducting the behaviour of the soil interacting with a foundation from degradation curves characterising the soil stiffness.
Quantifying the relative strengths of railway ballasts
Authors: Lim W. L. , McDowell G. R. , Collop A. C.
Published: November 2009

It is important to be able to distinguish easily between ballasts of poor quality and good quality in terms of strength. For a range of uniformly graded granular materials compacted to the same relative density, there will be two important factors influencing the strength of the aggregate: particle strength and voids ratio (which will be a function of particle shape). Large oedometer tests have been performed in addition to box tests and single particle crushing tests and a new parameter, called the relative strength index, is defined to incorporate the effects of both particle strength and voids ratio. It is found that the relative strength index correlates well with the amount of degradation of ballast in both the large oedometer tests and the box tests, and therefore shows promise as a suitable method for comparing ballast types without having to apply thousands of cycles of load on each ballast.
The first 30 years of Lefkara Dam
Authors: Kyrou K. , Penman A. , Artemis C.
Published: November 2009

The 74 m high Lefkara embankment dam was built in the early 1970s for the Republic of Cyprus Water Development Department in order to supply domestic water to the cities of Famagusta and Larnaca. It is a rockfill dam with a central clay core composed of a combination of residual soils and colluvium supported by diabase rockfill shoulders. The dam was well instrumented using total pressure cells, piezometers and internal settlement gauges as well as surface settlement markers. These instruments are still working and the results are discussed in the paper. The dam is curved in plan since it was anticipated at the time of its design that the arched plan would help resist the thrust from the reservoir, but in reality it made virtually no difference to the behaviour that would be expected from a straight dam. Instead of the conventional vertical valve shaft for housing the water intakes at various levels, a semi-buried inclined gallery (shaft) has been adopted. Leakages of reservoir water through the gallery joints into the gallery have been creating problems at high reservoir levels. The embankment and its foundation proved to be quite watertight and the seepages recorded are remarkably low.
Design procedures for installation of suction caissons in clay and other materials
Authors: Houlsby G. T. , Byrne B. W.
Published: November 2009

Suction-installed skirted foundations, often referred to as suction caissons, are increasingly being used for a variety of offshore applications. In designing a caisson a geotechnical engineer must consider the installation process as well as the in-place performance. The purpose of this paper is to present calculation procedures for the installation of a caisson in clay. For clay sites, the caisson will often be used as an anchor, with the ratio of the skirt length (L) to the diameter (D) as high as 5. Calculation methods are presented for determining the resistance to penetration of open-ended cylindrical caisson foundations with and without the application of suction inside the caisson. Comparisons between predictions and case records are made. A companion paper describes the calculation procedure for installation in sand soils. Finally, comments are made here about installation in a variety of soils other than homogeneous deposits of clay or sand.
Deformation and stability regression models for soil nail walls
Authors: Sivakumar Babu G. L. , Singh V. P.
Published: November 2009

Lateral displacement and global stability are the two main stability criteria for soil nail walls. Conventional design methods do not adequately address the deformation behaviour of soil nail walls, owing to the complexity involved in handling a large number of influencing factors. Consequently, limited methods of deformation estimates based on empirical relationships and in situ performance monitoring are available in the literature. It is therefore desirable that numerical techniques and statistical methods are used in order to gain a better insight into the deformation behaviour of soil nail walls. In the present study numerical experiments are conducted using a 24 factorial design method. Based on analysis of the maximum lateral deformation and factor-of-safety observations from the numerical experiments, regression models for maximum lateral deformation and factor-of-safety prediction are developed and checked for adequacy. Selection of suitable design factors for the 24 factorial design of numerical experiments enabled the use of the proposed regression models over a practical range of soil nail wall heights and in situ soil variability. It is evident from the model adequacy analyses and illustrative example that the proposed regression models provided a reasonably good estimate of the lateral deformation and global factor of safety of the soil nail walls.
Effect of fibres on the mechanical properties of clayey soil
Authors: Attom M. F. , Al-Akhras N. M. , Malkawi A. I. H.
Published: November 2009

This paper presents the effect of short, discrete, randomly oriented fibres (natural and synthetic) on the mechanical properties of clayey soils. The mechanical properties investigated include peak unconfined compressive strength, stiffness and ductility. Three types of clayey soil were obtained from the eastern part of Irbid city in northern Jordan. Two types of fibre were used in this study: nylon and palmyra fibres, with aspect ratios (L/d) equal to 75. The clayey soils were mixed with fibres at five different percentages by volume of solid soil particles: 1%, 2%, 3%, 4% and 5%. The results showed that the peak unconfined compressive strength, stiffness and ductility of the clay–fibre mixture increased with fibre content. The post-peak softening in compression resistance decreased with increasing fibre content. The relative unconfined compressive strength increased with fibre content. Palmyra fibre showed a higher increase in the relative unconfined compressive strength than nylon fibre when mixed with clayey soil, for all fibre contents. Furthermore, the clayey soil with a high activity index showed greater improvement when mixed with fibres than that with a low activity index.
Compaction delay characteristics of clay with cement kiln dust
Authors: Brooks R. M. , Udoeyo F. , Takkalapelli K. V.
Published: November 2009

The study investigates the influence of compaction delay on some engineering properties of Philadelphian clay–cement kiln dust mix. The characteristics of the soil investigated were the unconfined compressive strength, California bearing ratio (CBR) and swell potential. It was observed that adding cement kiln dust to the Philadelphian clay significantly improved the aforementioned properties. The Student's t-test conducted with alpha equal to 0·05 and 0·005 chosen as significant and highly significant levels in this study has shown that there was no significant difference in unconfined compressive strength, CBR or swell potential of most Philadelphian clay soil samples compacted for between 1 h and 3 h. However, for samples compacted for between 1 h and 72 h delay there were significant statistical differences in the value of the measured characteristics. The results of the Student's t-test mean that, for the Philadelphian clay, compaction before 3 h of mixing yields maximum benefits. Delay up to 72 h results in significant loss of strength properties. Therefore prior arrangements should be made for compaction before mixing, to the extent possible.
Role of amount and type of clay in the lime stabilization of soils
Authors: Sivapullaiah P. V. , Sridharan A. , Bhaskar Raju K. V.
Published: November 2009

The effect of quantity of lime and duration of curing on the basic properties of a black cotton soil has been studied in this paper. The optimum lime content was found to be 6%. To investigate the role of clay content, black cotton soil containing different amounts of clay size fractions was also cured with 6% lime and the properties studied. To study the effect of type of clay mineral, commercially available kaolinite has also been mixed with 6% lime and the properties studied. Immediately on addition of lime, the liquid limit of black cotton soil decreases, but it increases with increase in duration of curing for any percentage of lime. These changes have been explained by changes in the thickness of the diffuse double layer and associated fabric changes. Studies on the changes in the properties of plastic limit, shrinkage limit and free swell index on lime addition help us to understand the controlling mechanisms. The effect of the double layer increases for montmorillonitic soils with increasing clay content, while fabric change controls the behaviour of black cotton soil with lesser clay content. The changes in properties of kaolinite are less pronounced than those in montmorillonitic clays on treatment with lime.

Dans la présente communication, on é tudie l'effet de la quantité d'argile et la durée du sé chage sur les propriétés du sol à coton noir. On a é tabli que la teneur optimale en argile est 6̥. Pour examiner le rôle de la teneur en argile, on a é galement soumis du sol contenant différentes quantités de fractions granulométriques de sol à coton noir avec un minimum de 6% d'argile et on a é tudié ses propriétés. Pour é tudier l'effet du type de minéral des argiles réfractaires, on a é galement mélangé de la kaolinite disponible dans le commerce avec 6% d'argile pour en é tudier les propriétés. Dès qu'on aioute de l'argile, la limite liquide du coton noir diminue, mais elle augmente avec l'augmentation de la durée de la cuisson, quel que soit le pourcentage d'argile. Ces changements ont é té expliqués par des variations de l'épaisseur de la double couche diffuse et des changements connexes de la structure. Des é tudes sur l'effet des variations des propriétés de la limite plastique, la limite de retrait et l'indice l'affaissement libre sur l'adjonction d'argile nous aident à comprendre les mécanismes de contrô le. L'effet de la double couche augmente pour les sols montmorillonitiques avec une teneur croissante en argile, alors que le changement de la structure détermine le comportement du sol à teneur en argile inférieure. Les changements des propriétés de kaolinite sont moins prononcés que ceux des argiles montmorillonitiques sur le traitement à l'argile.
Engineering behaviour of wood-ash-modified soils
Authors: Rao S. M. , Venkatarama Reddy B. V. , Muttharam M.
Published: November 2009

This paper examines the physico-chemical and engineering properties of wood-ash-modified soils from six different locations in Karnataka State, India. Laboratory results indicated that the modified soils from different locations contained comparable residual organic contents, but variable residual ash contents. All the ash-modified soils had unusually high exchangeable potassium contents. Experimental results also showed that these ash-modified soils predominated in silt-sized particles, were less plastic, exhibited lower standard Proctor maximum dry density and optimum moisture content values, and lower swell- shrink potentials than the natural black cotton soil (BCS) specimens. Experimental results suggested that wood-ash modification and lime stabilization similarly affect the index and compaction characteristics of expansive BCS.

Dans cette étude, nous examinons les propriétés physicochimiques et mécaniques des sols modifiés au bois et à la cendre dans six endroits différents dans l'état de Karnataka en Inde. Les résultats obtenus en laboratoire indiquent que les sols modifiés venant de ces divers endroits ont des teneurs comparables en matières organiques résiduelles mais que les teneurs en cendre résiduelle varient. Tous les sols modifiés à la cendre ont des teneurs en potassium échangeable anormalement élevées. Les résultats des expériences montrent aussi que, par rapport aux spécimens de sol de coton noir naturel (BCS), ces sols modifiés à la cendre ont une prédominance de particules de taille silteuse, sont moins plastiques, montrent une densité sèche maximum Proctor plus basse, ont un contenu humide optimum et des potentiels de gonflement contraction inférieurs. Les résultats expérimentaux suggèrent que la modification au bois et à la cendre et la stabilisation à la chaux affectent de manière similaire l'indice et les caractéristiques de compactage des sols BCS expansifs.
Simplified models for soil-nail lateral interaction
Authors: Tan S. A. , Luo S. Q. , Yong K. Y.
Published: November 2009

A series of simplified failure modes has been used in this paper to describe the behaviour of soil-nail lateral interaction. The criteria for determination of the possible failure modes for a soil-nail structure are set out on the basis of the relative stiffness and strengths of the soil and nail and the local relative lateral displacement across the shear zone. This local relative displacement is produced along a potential sliding surface of the reinforced soil-nail retaining structure. Expressions for calculation of soil-nail lateral resistance have been derived for each potential failure mode. It is found that soil-nail lateral resistance is dependent not only on the relative stiffness and yield strengths of the soil and nail but also on the local relative lateral displacement across the shear zone. Good agreement among the results of numerical simulation of soil-nail lateral performance, published experimental data and theoretical predictions have been demonstrated, to support the validity of the proposed approach for estimating soil-nail lateral resistance capacity in soil-nailing design.

Dans cette étude, nous avons utilisé une série de modes de défaillance simplifiés pour décrire le comportement de l'interaction latérale sol-clou. Nous donnons les critères de détermination des modes de défaillance possibles pour une structure sol-clou en nous basant sur la rigidité et la résistance relatives du sol et du clou et sur le déplacement latéral relatif local à travers la zone de cisaillement. Ce déplacement relatif local se produit le long d'une surface de glissement potentielle dans la structure de soutènement renforcé sol-clou. Nous en avons déduit les expressions pour le calcul de la résistance latérale sol-clou pour chaque mode de défaillance potentiel. Nous avons trouvé que la résistance latérale sol-clou dépend non seulement de la rigidité relative et des limites élastiques du sol et du clou mais aussi du déplacement latéral relatif local à travers la zone de cisaillement. Nous démontrons qu'il existe une bonne corrélation entre les résultats de la simulation numérique de la performance latérale sol-clou, les données expérimentales publiées et les prévisions théoriques, afin de soutenir la validité de l'approche proposée pour estimer la capacité de résistance latérale sol-clou lors de la conception d'un cloutage de sol.
Electro-osmotic consolidation of soft Bangkok clay with prefabricated vertical drains
Authors: Bergado D. T. , Balasubramaniam A. S. , Patawaran M. A. B. , Kwunpreuk W.
Published: November 2009

The response of reconstituted soft Bangkok clay to electroosmotic consolidation was investigated using the small cylinder electro-osmotic cell and the large consolidometer. Test results indicated that employing electro-osmosis to induce consolidation produced a 3 to 4·4 times faster rate of consolidation. An 11·6–58% increase in shear strength with the reduction of water content was achieved for treated samples. In contrast, only 9·8–19·5% increase in shear strength was achieved without treatment. It was found that the 120 V/m voltage gradient and the 24 h duration of polarity reversal interval had maximum effect on the shear strength distributions and settlements between the electrodes.

Nous avons étudié la réponse d'une argile tendre reconstituée de Bangkok à la consolidation électro-osmotique en utilisant la petite cellule électro-osmotique cylindrique et le grand consolidomètre. Les résultats des essais montrent que l'emploi de l'électro-osmose comme moyen de consolidation produit une consolidation de 3 à 4,4 fois plus rapide. Pour les échantillons traités, nous avons obtenu une augmentation de 11,6 à 58% de la résistance au cisaillement avec la réduction du contenu en eau. A l'inverse, sans traitement, nous n'avons obtenu que 9,8 à 19,5% d'augmentation de la résistance au cisaillement. Nous avons trouvé que le gradient de tension de 120 V/m et l'intervalle de 24 heures pour l'inversion de polarité avaient un effet maximum sur les distributions de résistance au cisaillement et les tassements entre les électrodes.
Evaluation of chemical grouted region by resistivity tomography
Authors: Komine H.
Published: November 2009

In chemical grouting, a method to evaluate the region improved by the grouting has not yet been established. This problem has been a major obstacle to the enhancement of reliability of chemical grouting. To solve this problem, the author noted that the electrical resistivity of chemical grout is much lower than the electrical resistivities of ground and groundwater. This study investigated the applicability of resistivity tomography to the evaluation of regions improved by chemical grouting through model tests in the laboratory. The resistivity tomography can measure the resistivity distributions of ground before and after grouting. As a result, it was clarified that a relatively high degree of accuracy can be obtained in the evaluation of the improved regions made by chemical grouting. The method proposed to evaluate the improved region in chemical grouting utilizes data on ground resistivities before and after grouting which can be determined by resistivity tomography, and it has been demonstrating a satisfactory applicability.

En matière de stabilisation chimique, aucune méthode permettant d'évaluer la région améliorée par la stabilisation n'a pas encore été établie. Ce problème empêche d'améliorer la fiabilité de la stabilisation chimique. Pour le résoudre, l'auteur a noté que la résistivité électrique du scellage chimique est bien plus basse que la résistivité électrique du sol et des nappes d'eau souterraines. Cette étude, au moyen d'essais sur maquettes en laboratoire, se penche sur l'applicabilité de la tomographie de résistivité pour évaluer les régions améliorées par une stabilisation chimique. La tomographie de résistivité peut mesurer les répartitions de résistivité du sol avant et après la stabilisation. Ainsi, il est apparu qu'on peut obtenir un degré d'exactitude relativement élevé dans l'évaluation des régions améliorées par une stabilisation chimique. La méthode proposée pour évaluer la région améliorée par stabilisation chimique utilise des données de résistivité du sol avant et après la stabilisation, données qui peuvent être déterminées par la tomographie de résistivité. Cette méthode montre une applicabilité satisfaisante.
Optimising binder blends for shallow stabilisation of fine-grained soils
Authors: Lindh P.
Published: November 2009

Soil stabilisation techniques often use cement or lime as stabilising agents. Lately there has been an increase in using blended binders. Mixing cement with slag or cement with fly ash has gained in popularity. The prime purpose of blending binders is to reduce the costs. Other aims are to use waste material or to produce a new binder with better properties. Blending binders does not automatically result in a stabilising agent with better properties; in fact, the reverse might be the case. Results from several tests indicate that blended binders perform better than single binders. In some countries, blended binders have been manufactured for several years. This paper deals with both the performances of blended binders and single binders in different soils and with the techniques to evaluate the effects of blending binders.

Les techniques de stabilisation des sols utilisent souvent le ciment ou la chaux comme agents stabilisateurs. Les liants composés sont plus utilisés depuis quelque temps. Des mélanges fréquents portent respectivement sur le ciment de laitier ou le ciment mélangé avec des cendres volantes. L'objet principal de ces liants est d'abaisser les coûts: ses objectifs autres consistent en un recyclage de déchets ou en la réalisation d'un nouveau liant aux propriétés meillures. Le simple mélange de liants ne garantit pas un liant stabilisateur ayant de meilleures propriétés, le cas inverse est parfaitement possible. Selon les résultats de plusieurs essais les liants composés affichent de meilleures performances que les liants simples. Certains pays ont acquis une expérience de plusieurs années en la fabrication de liants composés. Le présent article traite d'une part des performances de liants composés et de liants simples appliqués à des sols variés, d'autre part des techniques pour é valuer les effets des liants composés.
Effects of electrode materials and current intermittence in electro-osmosis
Authors: Mohamedelhassan* E. , Shang* J. Q.
Published: November 2009

The effects of electrode materials and current intermittence on the coefficient of electro-osmotic permeability and the voltage loss at the soil-electrode interfaces are investigated using a marine soil. An electro-osmotic testing cell is designed and fabricated to measure the electro-osmotic induced flow under known boundary conditions. Six pairs of electrodes are tested for the voltage loss at the soil- electrode interfaces and for the coefficient of electroosmotic permeability. The losses in the applied voltage are found to be dependent on the anode material and are less in metallic anodes (steel or copper) than carbon anodes. The coefficients of electro-osmotic permeability are relatively independent of the electrode materials and are controlled by the effective electric field intensity in the soil. The application of current intermittence generates a higher electro-osmotic flow than continuous d.c. for the same applied voltage and the open electric circuit is superior to the short electric circuit configuration. The coefficient of electro-osmotic permeability is maximum using current intermittence of 2 min on/1 min off and open-circuit configuration for the soil tested.

Nous étudions, en utilisant un sol marin, les effets des matériaux des électrodes et de l'intermittence de courant sur le coefficient de perméabilitéélectro-osmotique et la perte de tension aux interfaces sol-électrode. Nous avons conçu et fabriquéune cellule d'essai électro-osmotique pour mesurer le flux provoquépar électro-osmose en conditions limites connues. Nous testons six paires d'électrodes pour la perte de tension aux interfaces sol-électrodes et pour le coefficient de perméabilité électroosmotique. Nous constatons que les pertes de tension appliquée dépendent du matériau de l'anode et sont moindres avec les anodes métalliques (acier ou cuivre) qu'avec les anodes en carbone. Les coefficients de perméabilité électro-osmotique sont relativement indépendants du matériau de l'électrode et sont fonction de l'intensité du champ é lectrique effectif dans le sol. L'application d'un courant intermittent produit un flux é lectro-osmotique plus e levéque l'application d'un courant direct continu pour la même tension appliquée; et le circuit é lectrique ouvert est supérieur àla configuration de circuit é lectrique court. Le coefficient de perméabilitéé lectro-osmotique est à son maximum quand on utilise un courant intermittent activé pendant 2 minutes et désactivépendant 1 minute et une configuration à circuit ouvert pour le sol testé
Properties of soil-cement stabilised with deep mixing method
Authors: Fang Y. S. , Chung Y. T. , Yu F. J. , Chen T. J.
Published: November 2009

Engineering properties of soil-cement obtained from the construction site of a liquid natural gas (LNG) station are reported in this paper. To increase the bearing capacity and to reduce settlements of the soft ground under pipeline and building loads, soil-cement columns were fabricated with mechanical deep-mixing method. Fourteen days after construction, 50 mm-diameter cylindrical specimens were drilled from the site and then tested in the laboratory. Based on the experimental results it is found that the recovery ratio varies from 71% to 90%. Shear modulus of the ground increased by about 40–140 times as a result of deep mixing. Uniaxial compressive strengths of the specimens obtained are quite scattered, however, the test results are greater than the design strength 2·0 MPa. Compressibility of the ground has reduced by 45% to 90%, as a result of ground modification.

Nous donnons dans cet article les propriétés techniques d'un sol-ciment, relevées sur le chantier de construction d'une station de gaz naturel liquéfié (GNL). Pour augmenter la portance et réduire les tassements du sol tendre sous les pipelines et les charges de construction, des colonnes de sol-ciment ont été fabriquées en utilisant une méthode de mixage profond. Quatorze jours après la construction, des spécimens cylindriques de 50 mm de diamètres ont été extraits du site et testés en laboratoire. Sur la base de ces expériences, il apparaît que le taux de récupération varie entre 71% et 90%. Le module de cisaillement du sol se trouve multiplié par un facteur de 40–140 environ, à cause du mixage profond. Les résistances à la compression uniaxiale des spécimens sont assez dispersées mais les résultats des essais sont supérieurs à la résistance nominale de 2·0 MPa. La compressibilité du sol se trouve réduite de 45 à 90% àcause de la modification du sol.
A triaxial system for vibro-replacement liquefaction mitigation studies
Authors: Blewett J. , Woodward P. K.
Published: November 2009

Vibro-replacement is a cost-effective method of stabilising liquefiable soils. The exact mechanisms by which vibro-columns can mitigate liquefaction are complex and difficult to verify in the field. A novel low-cost, seismic frequency triaxial testing system is presented, which has the capability to apply a drained cyclic load to composite columnar samples. Potentially, the facility can provide a comprehensive examination of the parameters involved in liquefaction mitigation by columnar inclusions. The testing facility is used here to investigate the use of crushed glass as a columnar backfill material.

La mise en place vibro est une meéthode économique pour stabiliser les sols liquéfiables. Les mécanismes exacts qui permettent à des colonnes vibrantes d'atténuer la liquéfaction sont complexes et difficiles à vérifier sur le terrain. Nous présentons un nouveau système peu coûteux pour tester la fréquence sismique triaxiale, système qui est capable d'appliquer une charge cyclique drainée à des échantillons de colonnes composites. Ce système peut potentiellement permettre un examen approfondi des paramètres entraînant l'atténuation de la liquéfaction par inclusions colonnaires. Nous utilisons ce matériel 'essai pour étudier l'utilisation de verre pilé comme matériau de remplissage des colonnes.
Binder distribution in lime—cement columns
Authors: Larsson S.
Published: November 2009

The mixing of soil and binders is a very complex process. The object of the mixing process is to distribute the binder and to achieve a satisfactory mixture for the particular purpose. The requirements on homogeneity may differ for each application. The assessment and definition of mixing quality are difficult and very expensive. This paper discusses the concept of mixing quality with respect to the binder distribution, and the use of mixing indices, as a quantitative assessment. The possibility of using mixing indices with the lime–cement column method is taken up. Statistical analysis was performed on a number of samples taken from four lime–cement columns at Arboga, Sweden. The sampling methodology, the scale of scrutiny and thus the influence of the sample size are discussed. The study shows that mixing indices can be used as a quantitative measure of the mixing quality. The results indicate that the sample size has a considerable influence when the mixing quality is poor and a lesser influence when the mixing quality is relatively good. It is also shown that it is difficult to draw conclusions concerning binder distribution from only a few samples, since the distribution may vary. With more extensive knowledge, it may be possible to assess the mixing quality from only a few samples.

Le processus consistant à mélanger de la terre et des agglomérant est très complexe. Son but est de bien répartir l'agglomérant et d'obtenir le mélange qui convient à une application donnée. Les critères d'homogénéité diffèrent selon les utilisations. Les procédés pour évaluer et déterminer la qualité du mixage sont difficiles et couûtent très cher. Cet exposé examine le concept de qualité de mixage en ce qui concerne la répartition de l'agglomérant; nous étudions aussi l'emploi d'indices de mixage pour faire des évaluations quantitatives. Nous examinons la possibilité d'utiliser des indices de mixage avec la méthode à colonne chauxciment. Nous avons effectué une analyse statistique sur un certain nombre d'échantillons pris dans quatre colonnes chaux-ciment à Arboga en Suède. Nous passons en revue la méthodologie d'échantillonnage, le niveau de recherche et donc l'influence de la dimension des échantillons. L'étude montre qu'il est possible d'utiliser des indices de mixage pour mesurer de manière quantitative la qualité de mixage. Les résultats indiquent que la dimension des échantillons a un effet considérable quand le mixage est de mauvaise qualité et moins d'effets quand le mixage est relativement bon. Nous montrons également qu'il est difficile de tirer des conclusions au sujet de la répartition de l'agglomérant d'après quelques échantillons seulement, étant donné que la répartition peut varier. Si l'on obtient des renseignements plus poussés, il pourra être possible d'évaluer la qualité de mixage d'après seulement quelques échantillons.
Use of reinforced soil walls bearing structures
Authors: Arab R. , Villard P. , Gourc J. P.
Published: November 2009

There can be no doubt that there are now real economic benefits to be gained from using retaining walls as bearing structures. To justify this technical option, research programmes have been undertaken in a variety of European countries, involving full-scale experiments on instrumented structures subjected to localised surcharge loading. In France two full-scale instrumented structures were built and tested until failure. At the same time, a finite-element numerical modelling system was established and used to optimise structural dimensions after calibration with respect to experimental results. The results of the model–experiment comparison are presented and analysed along with the results of the parametric study which sets forth a number of recommendations concerning the design of this type of structure.

L'utilisation des murs de soutènement comme structure porteuse représente à l'heure actuelle un intérêt économique certain. Pour justifier ce choix technique, des programmes de recherche, mettant en œuvre des expérimentations en vraie grandeur sur des ouvrages instrumentés sollicités par des charges localisées en tête, ont été réalisés dans différents pays européens. En France deux ouvrages en vraie grandeur instrumentés ont été réalisés et testés jusqu' à la rupture. Conjointement une modélisation numérique par éléments finis a été mise en œuvre et une fois validée sur les résultats expérimentaux, utilisée pour optimiser le dimensionnement des ouvrages. Les résultats de la confrontation modélisation–expérimentation sont présentés et analysés tout comme les résultats de l'étude paramétrique qui ont permis de dégager des recommandations techniques quant à la conception de ce type d'ouvrage.
Mutifactorial study of macroscopic properties of solidified sludge. Part I: Compressive strength
Authors: Boutouil M. , Levacher D.
Published: November 2009

Dredged materials management is significantly affected both by the scarcity of landfills and by environmental regulations. It has been found that solidification can improve the mechanical properties of sediments, rendering them fit for reuse in various applications. This paper concerns experiments and discussion results on the effect of various factors (cement content, type of cement, curing conditions and additive content) on the macroscopic behaviour, specifically the unconfined compressive strength (UCS) before and after immersion in water, of a solidified harbour sludge. The results discussion is based on the use of a statistical analysis by means of ‘fractional factorial experimental design’. The chosen model was found to fit adequately the variations of the compressive strength, and the statistical investigations of the effect of the studied factors on UCS values before and after immersion highlighted the following main conclusions. Dispersion of UCS values tends to increase with an increase in the UCS average value. Cement content and curing conditions (with or without loss of moisture) were found to be the major factors, with storage having an increasing effect on the compressive strength after immersion. Although the UCS tends to respect cement class strength, the related coefficients are statistically insignificant. Increasing additive content (lime, road binder, fly ash and silica fume) led to an improvement in UCS of 0·3–1·0 MPa. Fly ash was observed to be insignificant for UCS values before immersion but was significant for UCS after immersion.

La gestion et le devenir des matériaux de dragage sont de plus en plus confrontés à la raréfaction des sites de dépôt à terre et aux règlementations environnementales. La technique de solidification permet d'améliorer les caractéristiques mécaniques en vue d'une valorisation. Dans cet article, on présente les résutats d'un travail expérimental sur l'influence de différents facteurs (dosage et type de ciment, mode de stockage et additifs) sur la résistance à la compression avant et après immersion du sédiment solidifié. Le modèle proposé semble traduire d'une manière satisfaisante les variations de la résistance et l'analyse satistique des effets des facteurs aboutit aux conclusions suivantes: La dispersion de la résistance à la compression tend à augmenter avec l'augmentation de la résistance moyenne. Le dosage en ciment et le mode de stockage sont les facteurs les plus prépondérants, avec une augmentation de l'effet du stockage sur la résistance après immersion. Bien que l'évolution de résistance à la compression tend à respecter les classes de résistance des ciments, les coefficients relatifs au type de ciment sont non-significantifs. L'augmentation du dosage en additifs conduit à une améliration de la résistance de 0·3–1·0MPa. En outre, les cendres volantes se sont révélées statistiquement non-significantifs vis-à-vis de la résistance avant immesion mais significatifs vis-à-vis de la résistance après immersion.
Influence of grouts on unconfined creep behaviour of grouted Fontainebleau sand: experimental study and primary creep modelling
Authors: Delfosse-Ribay E. , Djeran-Maigre I. , Cabrillac R. , Gouvenot D.
Published: November 2009

This article deals with the creep behaviour of two new grouts—a cement-based grout and a mineral-based grout—in comparison with silicate grout. Results show that Fontainebleau sand grouted with new grouts presents few creep strains whereas silicate grout causes sand to become viscous. Long-term unconfined creep tests are performed on grouted sand for creep study and creep limit determination. Creep curves prove that new-generation grouted sands are stable over time. Primary creep modelling was done with the Singh and Mitchell law for all grouted sands, and parameter values were discussed. A parametric study makes evident the influence of the different parameters of this model.

Cet article traite du comportement au fluage de deux nouveaux coulis, l'un à base de ciment et l'autre d'origine minérale, par comparaison avec le gel de silice. Les résultats obtebus montrent que le sable de Fontainebleau injecté avec ces nouveaux coulis présente peu de déformations par fluage alors que le sable injecté au gel de silice présente un caractére visqueux. Des essais de fluage de longue durée ont été réalisés sur du sable injecté dans le but de déterminer la charge limite de fluage et d'étudier le fluage des sables injectés. Ces essais montrent que les sables injectés avec les nouveaux coulis présentent un caractère stable dans le temps. Le fluage prinaire a été modélisé à l'aide la loi de Singh et Mitchell pour tous les types de sables injectés et une discussion sur l'influencedes différents facteurs intervenant a été développée sur la base d'une étude paramétrique.
Analysis of the consolidation of laterally loaded micropiles
Authors: Shahrour I. , Ata N.
Published: November 2009

This paper includes a numerical study of the consolidation of micropiles submitted to lateral loading. It is performed using a three-dimensional finite-element modelling with Biot's theory for the fluid-skeleton coupling. The behaviour of the soil is described using an elastoplastic constitutive relation with a non-associated Mohr–Coulomb flow rule. The first part of the paper concerns an analysis of the influence of the pore pressure build-up on the response of a single pile to a lateral loading; this response is compared to the micropile response under drained condition. The second part deals with the behaviour of groups of micropiles during consolidation. It includes an analysis of the influence of both micropiles spacing and number on the consolidation of groups of micropiles.

Cet article comporte une étude numérique de la consolidation des micropieux soumis à un chargement latéral. L'étude est réalisée à l'aide d'une modélisation tridimensonnelle par éléments finis fondée sur la théorie de Biot pour le couplage fluide-squelette. Le comportement du sol esst décrit par un modèle élastoplastique utilisant le critère non associé de Mohr–Coulomb. La première partie de l'article présente l'influence de la pression interestitielle induite par le chargement sur le comportement d'un micropieu isolé. La seconde partie traite des groupes de pieux. Elle comporte une analyse de l'influence de l'espacement des micropieux et de leur nombre sur la consolidation des groupes de micropieux.