bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical properties of air-cement-treated soils
Authors: Hayashi Y. , Suzuki A. , Matsuo A.
Published: November 2009

As the effect of mix proportions on the mechanical properties of air-cement-treated soils has not been clear until now, the mechanical properties of cement-treated and air-cement-treated soils were compared in conditions of equivalent strength in unconfined compression. Owing to differences in the cement content, the air-cement-treated soil was more brittle and its strength less dependent on the confined stress than that of the cement-treated soil. A unique failure criterion can be obtained for each soil regardless of the drainage conditions. The confined pressure dependence reduced when both cement and air-void contents were increased; however, the deviator stress was unaffected by the confining pressure at small strain values. The unconfined compression strength is also useful for determining the mechanical properties of treated soils.

Les effets du dosage des éléments sur les propriétés mécaniques des sols traités à l'air-ciment étant jusqu′ à aujourd′ hui peu connus, nous avons conduit une étude des propriétés des sols traités au ciment et des sols traités à l'air-ciment par comparaison dans des conditions équivalentes de résistance à la compression unidimensionnelle. Les sols traités air-ciment se sont avérés un matériau plus friable et de résistance moins dépendante des tensions d'étreinte que les sols traités au ciment en raison de la difference de teneur en ciment. Il est possible d'obtenir un critère de rupture unique pour chaque sol quelles que soient les conditions de drainage. La dépendance à la pression d'étreinte devient moindre quand la teneur en ciment et la teneur en poches d'air augmente mais la contrainte déviatrice n'est pas affectée par la pression d'étreinte pour des petites valeurs de dilatation. La résistance à la compression unidimensionnelle peut également être utile pour connaître les propriétés mécaniques des sols traités.
Feasibility assessment of electro-osmotic consolidation on marine sediment
Authors: Mohamedelhassan E. , Shang J. Q.
Published: November 2009

A procedure is developed for the feasibility assessment of electro-osmotic (EO) consolidation of geomaterials, including fine-grained soils, sediments and mine tailings containing clay minerals. The assessment is based on a series of parametric studies to examine the effectiveness and efficiency of the electro-osmotic process in a site-specific geomaterial. The feasibility study on a natural marine sediment recovered from the seabed of the Korean coast is presented to illustrate steps involved in the assessment. In particular, the effects of soil pore fluid salinity and void ratio on electro-osmotic consolidation using intermittent current are examined. The results show that the effectiveness of electro-osmotic consolidation, assessed by the EO permeability ratio, increases when the soil void ratio decreases, whereas it is not significantly affected by the pore fluid salinity. The study also illustrates that the power consumption in an electro-osmotic consolidation process is predominantly controlled by the electrical conductivity of the soil, which is a function of the soil pore fluid salinity and void ratio.

Une procédure est développée pour l'évaluation de la faisabilité de la consolidation électro-osmotique (EO) des géomatériaux incluant les sols granulaires fins, les sédiments et les résidus miniers. L'évaluation est basée sur une série d'études paramétriques pour examiner l'efficacité et l'efficience du processus électro-osmotique dans un géomatériau spécifique. On présente l'étude de l'efficacité sur sédiment marin naturel provenant d'un fond marin de la cote coréenne pour illustrer les é tapes comprises dans l'évaluation. On examine, en particulier, les effets de la salinité de l'eau interstitielle et de l'indice des vides sur la consolidation électro-osmotique en utilisant le courant intermittent. Les résultats montrent que l'efficacité consolidation électro-osmotique, évaluée par le rapport de permeéabilité EO, augmente quand l'indice des vides du sol décroît tandis qu'elle n'est pas affectée de façon significative par la salinité de l'eau interstitielle. L'étude illustre aussi que la consommation de puissance dans un processus de consolidation électro-osmotique est principalement contrôlée par la conductivité é lectrique du sol qui est une fonction salinité de l'eau interstitielle et de l'indice des vides.
Stabilising effects of different binders in some Swedish soils
Authors: Åhnberg H. , Johansson S.-E. , Pihl H. , Carlsson T.
Published: November 2009

In Sweden, lime and lime–cement have been used for several decades as stabilising agents in deep stabilisation of soft soils. More recently, other types of binder have come into use, but so far only to a limited extent. In order to gather experience about the effect of various binders, laboratory tests have been performed on different types of soil stabilised with a range of binders. Lime, cement, fly ash and blast furnace slag in different combinations together with different admixtures, such as gypsum, silica fume and calcium chloride, have been used in the investigations. The variation in strength with type of binder has been studied, and comparisons have also been made with results from some previous investigations using different binders. The tests showed that there is no optimal, universal binder for stabilisation of the soils. Whereas some binders are robust, yielding good results in most types of soil, there are also binders that produce very good results in certain soils but poor results in others. Both similarities and differences in effects were found for different binders.

En Suède, la chaux et une combinaison chaux-ciment ont été utilisés depuis plusieurs décennies comme agents stabilisants pour la stabilisation de sols mous. Plus récemment, d'autres types de liants ont été utilisé, mais de façon limitée. Dans le but d'acquérir de l'expérience concernant l'effet de différents liants, un certain nombre d'essais en laboratoire ont été exécutés sur différents types de sols stabilisés avec différents liants. La chaux, le ciment, les cendres, et les scories de haut fourneaux combinés dans différents mélanges avec du gypse, de la silice et du chloride de calcium ont éte utilisés dans ces essais. La variation de la résistance avec le type de liants a été étudié et des comparaisons ont été faites avec des essais provenant d'études antérieures de différents liants. Les essais n'ont pas résulté en un liant optimal universel, mais ils ont démontré que certains liants affichent de bons résultats dans la plupart des types de sols étudiés alors que certains autres liants montrent de bons résultats dans certains sols et des mauvais résultats dans d'autres. Des similitudes ainsi que des différences se rapportant à l'effet de différents liants ont été enregistées au cours des essais.
Geoenvironmental aspects of chemically based ground improvement techniques for pyritic mine tailings
Authors: Mohamed A. M. O.
Published: November 2009

In this study, a review is made of the basic hydration processes and mineral transformation of the chemically based treatment techniques for pyritic mine tailings. Emphasis is given to the factors that influence the setting of the treatment agents and their interaction with the waste. A case study is presented and discussed. The success of the treatment technique is evaluated based on X-ray diffraction analysis, scanning electron micrographs and the hydro-mechanical properties (i.e. shear strength and hydraulic conductivity) of the treated samples.

Dans cette étude, nous passons en revue les processus élémentaires d'hydratation et la transformation minérale des techniques de traitements chimiques pour les résidus miniers pyriteux. Nous insistons sur les facteurs qui influencent la pose des agents de traitement et leur interaction avec les résidus. Nous présentons et examinons une histoire de cas. Nous évaluons le succès de la technique de traitement en nous basant sur une analyse de diffraction de rayons X, des micrographes électroniques à balayage et les propriétés hydro-mécaniques (c'est-à-dire la force de cisaillement et la conductivité hydraulique) des échantillons traités.
Laboratory evaluation of prefabricated vertical drains for use in soil vapour extraction systems
Authors: Collazos O. M. , Bowders J. J. , Bouazza A.
Published: November 2009

Volatile contaminants are more effectively recovered from the vadose zone by enhancing air phase transport rather than water phase transport. In this respect, soil vapour extraction (SVE) represents the benchmark process for remediation in the vadose zone. The ability of conventional SVE to remove volatile contaminants from highly permeable material (intrinsic permeability, K ⩾ 10−8 cm2) is well established. However, the conventional SVE process is difficult to implement in less permeable soils with intrinsic permeability varying between 10−8 cm2 and 10−10 cm2 (such as silty sand or silt). Incorporating prefabricated vertical drains in an SVE system can extend the effectiveness of SVE to lower-permeability soils by shortening the air-flow paths and ultimately expediting contaminant removal. One advantage of using prefabricated vertical drains instead of conventional SVE wells is that they can be installed very inexpensively. The objective of the work described in this paper is to develop the necessary parameters for effectively incorporating prefabricated vertical drains into an SVE remediation system.

On récupère les contaminants volatils de manière plus efficace dans la zone vadose en améliorant le transport de phase d'air plutôt que le transport de phase aqueuse. À cet égard, l'extraction de vapeur du sol (SVE) représente le processus standard pour les traitements améliorants dans la zone vadose. La capacité de la méthode SVE conventionnelle à extraire les contaminants volatils des matériaux très perméables (perméabilité intrinsèque, K ⩾ 10−8 cm2) est bien établie. Cependant, le processus SVE conventionnel est difficile à mettre en uvre dans des sols moins perméables dont la perméabilité intrinsèque varie entre 10−8 cm2 et 10−10 cm2 (comme le sable silteux ou le limon). Si l'on incorpore des drains verticaux préfabriqués dans un système SVE, on arrive à étendre l'efficacité de la méthode SVE à des sols moins perméables en raccourcissant les trajectoires d'écoulement d'air et finalement en accélérant le retrait des contaminants. Un des avantages à utiliser des drains verticaux préfabriqués au lieu de puits SVE conventionnels, c'est que ces drains peuvent être installés à peu de frais. L'objectif de cette étude est de développer les paramètres nécessaires à une incorporation efficace de drains verticaux préfabriqués dans un système de traitement SVE.
Soil improvement for a road using the vacuum preloading method
Authors: Yan S. W. , Chu J.
Published: November 2009

A case of using the vacuum preloading method to improve the foundation soil for a road in Tianjin, China, is presented. A vacuum load of 80 kPa was applied for 90 days to consolidate a 20 m thick soft clay layer. The ground settled for about 1·5 m. The average degree of consolidation estimated using settlement data was 90%. The undrained shear strength of the soil increased and the water content decreased after vacuum preloading. The procedures used for soil improvement, the instrumentation and the field monitoring data are described. Several issues concerning the practical aspects of the vacuum preloading method are discussed.

Nous présentons un cas utilisant une méthode de pré-charge sous vide pour améliorer le sol de fondation d'une route à Tianjin en Chine. Une charge sous vide de 80 kPa a été appliquée pendant 90 jours pour consolider une couche d'argile tendre épaisse de 20 m. Le sol s'est tassé sur environ 1,5 m. Le degré moyen de consolidation estimé d'après les données de tassement était de 90%. La résistance au cisaillement non drainé du sol a augmenté et le contenu en eau a diminué après la précharge sous vide. Nous décrivons les procédures utilisées pour améliorer le sol, l'instrumentation et les données de contrôle sur le terrain. Nous examinons plusieurs problèmes concernant les aspects pratiques de la méthode de précharge sous vide.
Stabilisation of retaining walls with non-grouted soil nails
Authors: Wehr W.
Published: November 2009

A new type of soil nailing, called sand anchors, has been developed to stabilise old retaining walls. Sand anchors bear without grout because of the constrained dilatancy of a dense granular material between anchor rod and borehole wall. They are environmentally friendly, can be used to preserve old monuments, provide additional drainage, allow immediate load application, are removable, and low cost. An example of stabilisation of an old retaining wall using sand anchors is presented, together with the results of pullout tests. In addition, some practical and design recommendations are given for applications of sand anchors in soils.

Un nouveau type de cloutage de sol, aux ancres de sable, a été mis au point pour stabiliser les vieux murs de soutènement. Les ancres de sable portent sans ciment en raison de la dilatance forcée d'une matière granulaire dense entre les tiges d'ancrage et la paroi du forage. Ces ancres sont sans danger pour l'environnement, peuvent être utilisées pour préserver les monuments anciens, apporter un drainage supplémentaire; elles peuvent accepter une application de charge immédiate, elles sont déplacables et peu coû teuses. Nous présentons un exemple de stabilisation d'un vieux mur de soutènement au moyen d'ancres de sable ainsi que les résultats des essais d'arrachement. En outre, nous formulons certaines recommandations d'ordre pratique et conceptuel quant à l'application de ces ancres de sable dans les sols.
Vacuum preloading method for improving soft soils of higher permeability
Authors: Gao C.
Published: November 2009

Experimental studies were carried out on the use of vacuum preloading to improve soft soils in the stacking yards for the first phase of the Port of Huanghua. Based on the results of the experiments, the method was employed for large-scale soil improvements in the yards. This success demonstrates the feasibility of using vacuum preloading to improve highly permeable soft soils. This paper presents the result of the improvement and the technological procedures adopted for implementing vacuum preloading. It also provides a useful summary of the use of the technique for improving soft soils of higher permeability.

Des études expérimentales ont été faites sur l'utilisation de la précharge de vide pour améliorer les sols tendres dans les docks de stockage, lors de la premiére phase de construction du Port de Huanghua. En raison du résultat de ces expériences, cette méthode a été employeé pour les améliorations de sol à grande échelle dans les docks. Ce succés dé montre qu'il est possible d'utiliser une précharge de vide afin d'améliorer les sols tendres trés perméables. Cet exposé présente les résultats de l'amélioration ainsi que les procédés technologiques adoptés pour mettre en uvre la précharge sous vide. Cet exposé offre également un résumé utile sur l'utilisation de cette technique pour améliorer les sols tendres ayant une perméabilité plus importante.
Effect of properties and length of reinforcement on load-carrying capacity of reinforced soil beds
Authors: Raghavendra H. B.
Published: November 2009

A reinforced soil bed is a soil bed carrying stiffer materials as reinforcement. The concept of reinforcing soil beds for improving the load-carrying capacity of soil is an age-old art. However, the technique is not fully exploited, as there are very few studies available pertaining to methods of design and analysis. Thus there is a need to understand soil-reinforcement interaction. This paper reports an attempt to understand the soil-reinforcement interaction in reinforced soil beds carrying footings. The investigation uses the finite element technique for the analysis. The paper presents the results of the analysis in the form of plots showing the effect of the properties and configuration of reinforcement on the load-carrying capacity of reinforced soil beds. The investigation throws light on the selection of the type of reinforcement and its optimum configuration for gaining the maximum advantage in reinforced soil beds.

Un lit de sol renforcé est un lit de sol portant des matiéres plus rigides qui servent à le consolider. L'idée de renforcer les sols pour améliorer leur portance remonte à la nuit des temps. Cependant cette technique n'est pas exploitée pleinement car il existe très peu d'études sur les méthodes de conception et d'analyse. C'est pourquoi il est nécessaire de comprendre l'interaction sol-renfort. Cet exposé décrit une tentative pour comprendre l'interaction sol-renfort dans des sols renforcés portant des assises. Cette investigation utilise la technique d'éléments finis pour l'analyse. L'exposé présente les résultats de l'analyse sous forme de tracés montrant les effets des propriétés et la configuration du renfort sur la capacité porteuse des lits de sol renforcés. Cette investigation permet de guider la sélection du type de renfort et de la configuration optimum pour obtenir des performances maximum des lits renforcés.
Characterisation of incinerator ash treated expansive soils
Authors: Al-Rawas A. A.
Published: November 2009

This paper investigates the physical, engineering, chemical and microfabric characteristics of two soils from Oman treated with incinerator ash produced at Sultan Qaboos University. First, the physical, engineering and chemical properties of the incinerator ash and the soils used were determined. The soils were then mixed with the incinerator ash at 0%, 10%, 15%, 20%, 25% and 30% by dry weight of the soils. Liquid limit and plastic limit tests were performed on specimens after 24 h of curing, whereas tests for swell per cent and direct shear were carried out on specimens cured for 1, 7 and 14 days. In addition, scanning electron microscope micrographs of representative treated samples were taken to examine the microfabric changes caused by the addition of the incinerator ash. The results showed that the incinerator ash used was a non-hazardous waste material. All treated samples showed a reduction in swell per cent and cohesion, and an increase in angle of internal friction with the addition of incinerator ash for all curing periods. The use of 20% and 30% additive showed clearly the development of aggregations that contributed to reduction of swell per cent of the soils.

Cet exposé é tudie les caractéristiques physiques, mécaniques, chimiques et microstructurales de deux sols d'Oman traités à la cendre d'incinérateur provenant de l'Université Sultan Qaboos. Tout d'abord, nous avons déterminé les propriétés physiques, mécaniques et chimiques de la cendre d'incinérateur et des sols utilisés. Ces sols ont ensuite é té mélangés à de la cendre d'incinération dans des proportions de 0%, 10%, 15%, 20%, 25% et 30% du poids à sec des sols. Nous avons réalisé des essais de limite liquide et de limite plastique sur des spécimens après 24 h de cuisson; nous avons réalisé les tests de gonflement et de cisaillement direct sur des spécimens cuits pendant 1, 7 et 14 jours. De plus, nous avons fait des micrographes par microscope é lectronique à balayage sur les é chantillons représentatifs traités afin d'examiner les changements de microstructure causés par l'adjonction de la cendre d'incinération. Les résultats ont montré que la cendre d'incinération utilisée était une matière de récupération non dangereuse. Tous les é chantillons traités ont montré une réduction du pourcentage de gonflement et de la cohésion ainsi qu'une augmentation de l'angle de friction interne lors de l'adjonction de la cendre d'incinération pendant toutes les périodes de cuisson. L'utilisation de 20% et de 30% d'additifs a montré clairement le développement d'agrégations qui ont contribué à la réduction du pourcentage de gonflement des sols.
Stabilisation of rice husk ash for use as cushion below foundations on expansive soils
Authors: Sivapullaiah P. V. , Subba Rao K. S. , Gurumurthy J. V.
Published: November 2009

Placing a cushion between the expansive soil and the foundation is an attractive proposal for overcoming the problems associated with construction of structures over expansive soils such as Indian black cotton soil. Extensive studies on cohesive non-swelling soil as a cushion have shown that it is ineffective over cycles of swelling and shrinkage of soil. The present paper explores the possibility of using rice husk ash (RHA) as a cushion. It was found that RHA stabilised with 3–9% of lime (LSR) or 10% of cement (CSR) and cured for about a week develops the properties required for an effective cushion material. Stabilised RHA reduces the bandwidth of vertical movements in expansive soil not only during the first cycle of swelling but also during subsequent cycles of swelling and shrinkage. The reduction increases with the thickness of the cushion. However, it is found that the middle level between the equilibrium swollen and equilibrium shrunken levels, called the operating level, decreases with the use of LSR/CSR as a cushion. LSR is more effective than CSR.

Le fait de placer un coussin entre un sol expansif et une fondation est une proposition intéressante pour venir à bout des problèmes associés à la construction de structures sur des sols expansifs comme le sol de coton noir indien. Des études poussées sur le sol cohésif non gonflant employé comme coussin ont montré qu'il n'a aucun effet sur des cycles de gonflement et de rétrécissement du sol. Cet exposé explore la possibilité d'utiliser de la cendre d'enveloppe de grains de riz (RHA) comme coussin. Nous avons trouvé que le RHA stabilisé avec 3 à 9 % de chaux (LSR) ou 10 % de ciment (CSR) et cuit pendant environ une semaine développait les propriétés nécessaires pour former un coussin efficace. Le RHA stabilisé réduit la largeur de bande des mouvements verticaux dans le sol expansif, non seulement pendant le premier cycle de gonflement mais aussi pendant les cycles ultérieurs de gonflement et rétrécissement. La réduction augmente en même temps que l'épaisseur du coussin. Cependant, il est apparu que le niveau moyen entre les niveaux d'équilibre gonflé et d'équilibre rétréci, appelé niveau opératoire, diminuait avec l'utilisation du LSR/CSR comme coussin. Le LSR s'est révélé plus efficace que le CSR.
Plastic limit and compaction characteristics of finegrained soils
Authors: Sridharan A. , Nagaraj H. B.
Published: November 2009

Laboratory determination of the compaction characteristics of soils is important for use in earthwork constructions. The purpose of compacting earth fills such as earth dams and embankments (highway, railway and canal) is to produce a soil mass that will satisfy the two basic criteria: reduction in settlement and increase in shear strength. For preliminary design and assessment, correlations with the liquid limit have been attempted by various investigators. However, from the present study it is seen that the correlations are not up to a satisfactory level. In this paper the results of detailed investigations carried out are examined to find which of the index properties correlate well with the compaction characteristics. In the analysis, apart from the authors' experimental results, results from the available literature have also been considered. It is found that the plastic limit bears a good correlation with the compaction characteristics, namely optimum moisture content and maximum dry unit weight, much better than liquid limit or plasticity index.

La détermination en laboratoire des caractéristiques de compaction des sols est importante pour les constructions à terrassement. Les remblais de terre compactée comme les levées de terre et les talus (autoroutes, voies ferrées et canaux) ont pour but de produire une masse de sol qui satisfera deux critères de base: la réduction du tassement et l'amélioration de la résistance au cisaillement. Pour la conception préliminaire et l'évaluation, divers chercheurs ont tenté d' établir des corrélations avec la limite liquide. Cependant, cette étude montre que les corrélations ne sont pas d'un niveau satisfaisant. Dans cet exposé, nous examinons les résultats de ces recherches détaillées afin de trouver celles des propriétés indice qui correspondent le mieux aux caractéristiques de compaction. Dans cette analyse, outre les résultats expérimentaux obtenus par les auteurs, les résultats disponibles publiés ont é galement é té pris en compte. Nous avons trouvé que la limite plastique montre une bonne corrélation avec les caractéristiques de compaction, nommément la teneur en eau optimum et le poids unitaire sec maximum, bien mieux qu'avec l'indice de limite liquide ou l'indice de plasticité.
Quality control in Central Japan International Airport construction
Authors: Kitazume M. , Satoh T.
Published: November 2009

Recently, a pneumatic flow mixing method has been developed for sea reclamation and land development, in which soft soil is mixed with a relatively small amount of stabilising agent in a transporting pipe. The soil mixture forms several separated mud plugs in the pipe, and is thoroughly mixed with the help of turbulent flow during transportation. This method was adopted to construct part of a man-made island for the Central Japan International Airport at the Ise Bay area in Nagoya. In the construction project, a total of 8.6 million m3 of dredged soil was stabilised by the method for sea reclamation. During the construction, quality control and assurance of manufacturing the treated soil were carried out with an automated control system and laboratory tests on sampled soils. In this paper, the quality control system developed in this project and the quality assurance of the improved ground are described in detail.

Récemment, une méthode de mixage á flux pneumatique a été développée pour récupérer des terrains sur la mer et les développer, méthode consistant à mélanger un sol tendre avec une quantité relativement faible d'agents stabilisants dans une canalisation de transport. Le mélange de terre forme plusieurs bouchons de boue séparés dans la canalisation et se trouve mélangé à l'aide d'un flux turbulent pendant le transport. Cette méthode a été adoptée pour construire une partie d'une île artificielle pour l'aéroport international Central Japan dans la région de Ise Bay ´ Nagoya. Dans le projet de construction, un total de 8,6 millions de m3 de sol draguéa été stabilisé par cette méthode. Pendant la construction, le contrîle et l'assurance qualité concernant la fabrication de sol traité ont été effectués par un systéme de contrîle automatisé et des essais en laboratoire suré chantillons de sol. Dans cet exposé, nous décrivons en détail le systéme de contrîle de la qualité développé dans ce projet ainsi que l´assurance qualité du sol amélioré.
Electrokinetic strengthening of soft clay
Authors: Mohamedelhassan E.
Published: November 2009

The use of electrokinetic treatment to decrease the water content and increase the shear strength, preconsolidation pressure and axial load capacity of a laboratory-prepared soft clay soil was investigated. The tests were carried out in four identical electrokinetic cells. The cell has a volume capacity of 10 litres. A DC voltage of 10 V was applied in the tests investigating the water content, shear strength and preconsolidation pressure. A DC voltage of 5 V was used in the tests investigating the axial load capacity. The energy consumption for each test was 54 W h. The electrokinetic treatment decreased the water content across most of the cell with the lowest water content near the anode (32·8 ± 2% in comparison with 52·7 ± 2·7% in the control) and increased the undrained shear strength across the cell with the highest shear strength reported near the anode (62·5 ± 6·2 kPa in comparison with 6·3 ± 2·1 kPa in the control). Electrokinetic treatment increased the preconsolidation pressure across the cell with the maximum pseudo-preconsolidation pressure near the anode (91 kPa in comparison with pre-loaded surcharge pressure of 10 kPa). The axial load capacity of the foundation model after the treatment was 156 N when the foundation model was serving as the anode and 173 N when the model was not used as an electrode. The loss in the mass of the foundation model by corrosion was 4·7% for the former and 0·4% for the latter.
Field performance of an excavation using sleeve grouting
Authors: Hsiung B. C. B.
Published: November 2009

In order to prevent the in-flow of groundwater, double-packer sleeve grouting is commonly applied in excavations in sand but a complete case history has been seldom reported in the literature. A case history of an excavation from Kaohsiung, Taiwan is presented in this paper, demonstrating the use of double-packer sleeve grouting in sand. In addition to details of grouting, measurements taken from this case history also include lateral wall movement, piezometric level, ground settlement, settlement and tilting of the structure, and crack width on the façade of an adjacent building. It was found that the use of sleeve grouting using appropriate materials and operation criteria can possibly reduce the permeability of sand to 5 × 10−4 mm/s. Sleeve grouting was found to limit the movement of water surrounding the excavation, which, in turn, led to limited ground movement and limited damage to adjacent buildings.
Improvement of machine foundations using reinforcement
Authors: Haldar S. , Sivakumar Babu G. L.
Published: November 2009

The main objective in the design of a machine foundation is to restrict the maximum amplitude of the foundation motion to within the safety limits. When the underlying soil is poor, pile foundations are generally used to reduce the amplitude of foundation motion in machine foundations. Analysis results pertaining to a field example in which the foundation response of a foundation for a generator was improved using a reinforced soil technique are presented herein. The numerical simulations with regard to the response of the foundation on the reinforced soil confirm the efficacy of the method adopted. The results show that reinforced soil foundations are viable alternatives to improve foundation response due to dynamic loading.
Fire modelling and resistance of RC columns subjected to natural fire
Authors: Yao Y. , Tan K.H.
Published: November 2009

Currently, the fire resistance design of reinforced concrete (RC) columns is essentially based on standard fire curves such as ISO 834 or ASTM E119. A more scientific approach based on realistic fire curves is useful to structural engineers as the method can take account of the actual fire load, ventilation openings and thermal properties of boundary walls in a fire compartment. In this paper, a simple and rational design method called the Rankine method is extended to natural fire conditions, which requires the concept of time equivalence for calculating the column fire resistance. By applying a time equivalence formula recommended in the Eurocode, the proposed Rankine method can be extended to different fire curves. As gas temperature plays a pivotal role in fire resistance calculations, a comparison study of time equivalence, zone modelling and Eurocode parametric fire equations is conducted. The study shows that the time equivalence approach is reasonably accurate and robust. A finite element code – SAFIR and a zone modelling program – Ozone are used to benchmark the simplified fire resistance calculation for RC columns.
Simulation of the Egyptian coastal ecosystem functions
Authors: Hamza W. , Ennet P. , Tamsalu R.
Published: November 2009

The mathematical models actually used to solve problems related to water resources and their management are complex in nature due to the fact that they are required to make an effective combination of a range of environmental reactions. These models typically consist of several parts: hydrodynamic, chemical and biological. In addition, atmospheric effects and other factors such as external forces must be considered when simulating existing conditions and in predictions of variations in the ecosystem functions. The aim of this study was to create a tool for operational prediction of the state of the aquatic ecosystem in the Egyptian Mediterranean coastal area. In order to accomplish this task the three-dimensional (3D) hydrodynamic–ecosystem FINEST model has been implemented over the entire Egyptian Mediterranean coastal area, and the validity of this model for the coastal area was tested. The coupled 3D hydro-ecosystem FINEST model is characterised by a double σ coordinate system, which divides the marine basin into two parts: an upper layer and a lower stratified layer. The ecosystem part of the model consists of the plankton community, inorganic nutrients, organic nutrients and detritus sub-models. The plankton community food web comprises four triplets where each triplet is formed by one heterotrophic predator-grazer and zooplankton prey, and one phytoplankton according to the class size. In the last (fourth) triplet the zooplankton prey is replaced by bacterioplankton. The application of the coupled 3D model on the ecosystem of the Egyptian Mediterranean coastal area demonstrates its suitability as an operational management system able to simulate external forcing factors (e.g. nutrients discharge, land runoffs, coastal meteorological forces, etc.) and predict the effects of these forces on the ecosystem components. A short-term validation test of specific parameters in the model has shown its sensitivity toward variations in the ecosystem due to external forcing factors. The results obtained from this test and presented here are preliminary ones however; further implementations of the model are in progress and will be published elsewhere with mathematical details of the model equations.
Ship effects at the bankline of navigation channels
Authors: Maynord S.
Published: November 2009

Ship effects at the bankline are most significant in confined channels and many ship channels contain a shallow berm on one or both sides of the channel. The shallow berm has a large impact on the ship effects at the bank-line. The dominant ship effects in confined channels are caused by the displacement effects of the ship and include long-period effects of drawdown, return velocity, transverse stern wave, and surge. Ships generally operate at 80–90% of limit speed and the displacement effects of the ship vary significantly with speed in this range. Analytical/empirical methods cannot address ship effects where shallow berms exist or complex channels. A numerical model, HIVEL2D, is used to determine ship effects in complex confined channels. Model-prototype comparisons show agreement of long-period effects such as drawdown. An empirical relationship is developed for determining surge magnitude but is limited to the waterway on which it was developed until additional data can be collected.
Coastline change and implications for habitat loss
Authors: Pontee N. I. , Drummond J. R. , Morrisey D. J.
Published: November 2009

This paper assesses the main controls on macro- and meso-scale evolution and contemporary morphological form of the East Lothian coastline. Importantly, many contemporary environments on this coast represent features inherited from earlier in the Holocene. Future changes to coastal environments are strongly dependent on sediment availability which is difficult to predict. However, it is likely that falling sea levels throughout much of the Holocene facilitated coastal accretion, which is now likely to be replaced by coastal erosion under rising sea levels and potentially increased storminess. The magnitude and location of future coastal change has important consequences for designated sites, which comprise habitats of local, national and international value. Although the loss of habitats is likely to be seen as a negative point, the potential for a return to a more dynamic functioning coast offers some conservation benefits, particularly for mobile habitats such as dunes.
Solving mild-slope equation by explicit scheme
Authors: Li B. , Fleming C. A.
Published: November 2009

An explicit scheme of Saul'yev for parabolic equations has been used to solve the time-dependent parabolic equation of the mild-slope equation. Theoretical analysis has been presented for stability and consistency of the explicit scheme applied to the mild-slope equation. The explicit scheme is simpler than most existing numerical schemes for solving the mild-slope equation, including elliptical, hyperbolic and parabolic (time-dependent) types and it is faster than the generalised conjugate gradient (GCG) scheme. It has about the same convergent speed as the alternating direction implicit (ADI) scheme for the parabolic equation, but the scheme is simpler. Experimental data obtained by Berkhoff et al. have been used to test the model. A comparison of present model results, for the case of an elliptic shoal, against the results of the GCG model and ADI model has been made and good agreement has been achieved. A nested grid method has also been combined with the present explicit scheme for solving the mild-slope equation. The simplicity of the explicit scheme makes the nested grid method very attractive for problems of wave propagation from deep to shallow water, where in deep water a coarse mesh can be used and in the shallow water region the mesh can be refined to achieve greater accuracy.
A numerical model of coastal overwash
Authors: Donnelly C. , Larson M. , Hanson H.
Published: November 2009

Overwash, the flow of water and sediment over the crest of a beach, contributes to flooding and the deposition of sand landward of the beach crest. Washover, the sand deposited by overwash, contributes to the sediment budget and migration of barrier islands. The ability to predict the occurrence, location, and thickness of overwash deposits is important for coastal residents, coastal town planners, environmental planners, and engineers alike. In this study, a numerical model that simulates the sediment transport and one-dimensional barrier profile change caused by overwash was developed. The magnitude of overwash and the morphology of washovers are dependent on the overwash regime. New formulae are developed to estimate the sediment transport rate over the beach crest for both run-up overwash, using ballistics theory, and inundation overwash, treating flow over the crest as weir flow. Two-dimensional flow is described on the back barrier by considering the continuity of a block of water at steady state, taking into account lateral spreading, friction, and infiltration. The model is tested against 26 different beach profile sets from several different locations, and several different storms, exhibiting a variety of initial morphologies. The model is capable of reproducing varying overwash morphology responses including dune crest erosion, dune destruction, barrier rollback, the thinning of a washover deposit on the backbarrier, and overwash over a multiple dune system.
Analytical model of beach erosion and overwash during storms
Authors: Larson M. , Donnelly C. , Jiménez J. A. , Hanson H.
Published: November 2009

During severe storms high waves and water levels may greatly impact the sub-aerial portion of the beach inducing significant morphological change at elevations that the waves can not reach under normal conditions. Morphological formations such as dunes and barrier islands may suffer from direct wave impact and erode. Overwash occurs if the wave run-up and/or the mean water level are sufficiently high allowing for water and sediment to pass over the beach crest, which in turn causes flooding and deposition of sediment shoreward of the crest. An analytical model of sub-aerial beach response to storms was developed based on impact theory, including overwash, and the evolution of schematised dunes was investigated. Furthermore, the analytical model was applied to the case of schematised barrier islands exposed to extensive overwash. After validation using field data, the analytical model was employed at two coastal sites, namely Ocean City on the United States east coast and the Ebro Delta on the Spanish Mediterranean coast, in order to calculate quantities for assessing the storm impact on beaches, such as eroded volume, overwash volume, beach crest reduction, and contour-line retreat. These quantities were subsequently analysed to derive empirical probability distribution functions to be utilised in different types of risk assessment concerning flooding and erosion in coastal areas.
Regional vulnerability analysis of Catalan beaches to storms
Authors: Mendoza E. T. , Jiménez J. A.
Published: November 2009

A framework to estimate coastal vulnerability to storm impacts at a regional scale is presented. It assesses the physical coastal vulnerability to storm impacts by separately estimating two components: flooding and erosion. It covers the following steps: characterisation of the forcing; evaluation of the induced beach response – inundation and erosion – (hazards quantification); coastal zone characterisation; definition of a coastal vulnerability index to storms – a composite of two partial vulnerability estimations, namely the flood vulnerability and the erosion vulnerability indices; and assessment of the coastal vulnerability. Instead of assessing the vulnerability associated with a given storm, the forcing is defined in terms of representative storms which are obtained by classifying storms in the area using a five-class system similar to that used for hurricanes (weak, moderate, significant, severe and extreme). Later, a vulnerability assessment for the entire coast to each storm category is produced. The method has been derived for and applied to the Catalan coast (north-west Mediterranean) but can be easily adapted to other coasts. It permits managers to identify coastal stretches sensitive to a given storm class for a given induced hazard (flooding, erosion or combination of both) to decide where to take actions.
Modelling shoreline evolution to enhance flood risk assessment
Authors: Stripling S. , Panzeri M.
Published: November 2009

Traditional flood-risk assessment considers coastal defences to be static features with foreshores represented simply with an assigned elevation and slope. However, beach elevations can vary rapidly over time, perhaps fluctuating seasonally, and often losing or gaining volume over a longer time period. Their dynamic nature ultimately influences the risk of coastal erosion and flooding. In a regional flood-risk assessment, in which beaches offer protection to a variety of backshore features such as seawalls, soft cliffs, and dunes, the ability to represent the beach dynamics fronting these defences is important. At regional scale, it is also necessary to consider the various backshore environments that may be encountered over a long stretch of coastline, and how their individual processes affect flood risk, particularly if they are erodible. An integrated framework of dynamically linked numerical models of coastal processes and statistical analysis methods is being developed to enhance regional flood-risk assessment via consideration of coastal evolution and foreshore morphodynamics. The framework is run entirely from within commercially available geographical information system software where model operation and numerical output is managed; standard geographical information system analysis and database capabilities are therefore also available within the modelling system. This paper outlines the basis of the modular framework, and demonstrates how flood-risk assessment is enhanced.
A stochastic method for predicting average beach shape
Authors: Li Y. , Reeve D.
Published: November 2009

Coastal flooding and erosion is a key problem for coastal management, and is complicated by features arising from the combination of meteorological and morphological characteristics. Variability in the position and level of beaches introduces uncertainty into predictions of coastal flood and erosion risks. In the present study the problem of the variability of the shoreline in an embayment was addressed. A simple but efficient statistical method to estimate the mean of a crenulated-shaped bay from its equilibrium shape is proposed with input as the wave climate. The mathematical modelling is based on ensemble averaging and an equilibrium bay shape model. In this work, the effects of the coefficients in the crenulated-shaped bay on the estimation are investigated in a sequence of problems of successive generality. As a specific example, the method has been applied to Christchurch Bay in the UK. The results indicate that the ensemble average approach could provide an efficient means of estimating beach response to random wave conditions
Learning from water sector reforms in Europe and Asia
Authors: Sohail Muhammad , Maslyukivska Olena
Published: November 2009

Water reforms in eastern Europe and central Asia (ECA) have their peculiarities defined by the historical conditions, where the main drivers were the socialist regime in the second half of the 20th century, its collapse and consecutive reforms targeting European Union integration. This paper presents a number of models of public–private partnership (PPP) in the water sector that are already working in the ECA region in the Czech Republic, Estonia, Hungary and Poland. The experience of the focus countries shows that the PPP transformed water utilities into more dynamic businesses, yet several problems undermining private sector efficiency exist, including the lack of infrastructure commitment on the side of the private partners and the lack of capacity within municipalities. The recommendations to improve the performance of PPP include insurance of transparency throughout the PPP project cycle, political cycle awareness, a planned employee reduction strategy, and an increase in quality of water and services as the strongest factor influencing the public’s perception.
Risk assessment as an explicit dimension for tender evaluation
Authors: Kwok E. C. S. , Ng S. H. S. , Tam J. C. L.
Published: November 2009

Tendering plays a very important role in a project’s life cycle and the outcome of the tendering process will have a direct impact on the overall project cost. It should be clear that in evaluating tenders, it is not just the bid price that counts. The quality of the selected contractor will in many ways affect the success of the project; that is delivery on time, within budget and to the required quality. The selection of a ‘wrong’ contractor could easily lead to late completion or over expenditure. Unfortunately, uncertainties of events and unpredictability of their outcome do exist at the tendering stage, the effect of which could be costly in some circumstances. To manage the risks associated with such uncertainties, the introduction of risk assessment as an explicit dimension in the tender evaluation process is proposed. In this approach, decision makers will be made aware of high-risk elements upfront so that more informed decisions can be made. With more supportive information in a complex decision-making process, it is hoped that project risks and, in turn, costs can be lowered as far as practicable.
Briefing: Challenges to ADR in the UK and internationally – a personal view
Authors: Loosemore D. J.
Published: November 2009

The effects of the economic downturn are being felt by everybody and the construction industry is no exception. During such times the potential for more claims and disputes is obviously increased. For that reason the industry needs to adapt to this changing environment and use it as an opportunity to improve its dispute management techniques. One way is to place a far greater emphasis on dispute avoidance; another is to encourage more use of other forms of alternative dispute resolution (ADR) in preference to adjudication when appropriate. It is hoped that this briefing note will generate support for these views and some constructive suggestions as to how such changes might best be implemented to address these challenges.