Papers by daniel levacher
La teneur en eau élevée des sédiments de dragage constitue un réel frein à toute valorisation mat... more La teneur en eau élevée des sédiments de dragage constitue un réel frein à toute valorisation matériau de ceux-ci. Elle l'est aussi pour le transport des sédiments dragués depuis des lieux difficilement accessibles comme les barrages, les lacs, les fleuves, les bassins portuaires… Ce transport nécessite de pouvoir manipuler les sédiments pour les charger : ils doivent être pelletables. Mais la notion de pelletabilité des sédiments reste à définir à partir de critères basés sur des paramètres intrinsèques des sédiments. Certains paramètres apparaissent en effet appropriés pour définir un ou plusieurs critères d'aptitude à la pelletabilité. Une fois retenus, ces paramètres doivent être déterminés par leur mesure directe ou déduits d'autres mesures. Cet ensemble de mesures implique la définition d'un essai spécifique dédié à la pelletabilité des sédiments. C'est l'objet de cette communication. Après avoir présenté les paramètres physiques et mécaniques propres à la pelletabilité des sédiments, un concept pour un essai de pelletabilité est proposé. Un premier prototype d'essai en version manuelle est décrit tout comme la procédure liée à son utilisation. Ce même prototype avec la même conception pourra être équipé pour une version automatisée sans aucune modification majeure. Cet équipement d'essai spécifique à la pelletabilité des sédiments pourra être adapté pour d'autres applications.
Japanese Geotechnical Society Special Publication, 2016
Determination of undrained shear strength Su and sensitivity St of soft soils and sediments are i... more Determination of undrained shear strength Su and sensitivity St of soft soils and sediments are important in geotechnical design as well as in sediment management. Usually these properties are deduced from laboratory or field tests. In lab, vane shear test (VST) is commonly used in clayey soft soils. Other testing is available such as the full flow penetrometers mainly used for in situ offshore engineering and for centrifuge modeling applications. Among them, the T-bar test (TBT) is not really used in geotechnical lab at 1 g level in small layers of soft soils put in containers. This paper deals with measurement of undrained shear strength (Su) of soft clays (kaolin clay) and dam sediment under conditions of natural drying, consolidation and drainage, using two different methodologies, namely T-bar and vane shear tests. Vane shear test is a standard test for Su measurement but not applicable for obtaining a continuous profiling of Su versus depth and it provides rather discrete measurements. Hence T-bar test has been used to observe a continuous phenomenon during shearing. Many studies have been reported comparing standard vane shear and T-bar tests to ensure applicability of the latter. Two different types of soils was tested to check the repetitiveness of testing and to validate previous works performed on Su measurement of kaolin clay using T-bar tests. Besides, in order to measure remolded shear strength, the vane is rapidly rotated through several revolutions until the clay becomes remolded. Again the same procedure is followed to measure the remolded shear strength. The ratio of two shear strengths measured (i.e. peak strength and remolded strength respectively) gives the sensitivity St. In addition to this, for comparative studies of TBT and VST, the methodology involves the rotation of vane blade 90 degrees anticlockwise and then 90 degrees clockwise. Although, this method is not usually used for VST testing, it enables to compare Su measured in anticlockwise rotation with the downward movement of T-bar. Likewise, Su is measured during clockwise rotation with the upward movement of T-Bar. In order to obtain compatibility between measurements made with T-bar and vane shear tests, it is interesting to study the ratio of measurements made by both tests. So, in order to do that, the peak value of each curve from vane shear test is compared with the average value of Su measured by T-bar test along the depth of blade insertion. This practice is appropriate for comparison because Su has been assumed as uniformly distributed over the entire height of the vane. So, in order to test the suitability of the comparison, the above practice is followed for all tests in kaolin clay and dam sediments. But still, it was interesting to observe the average of the ratios measured by different numbers of tests in kaolin and dam sediments and to compare them in order to see the applicability of the tests for different types of soils. So, average values of ratio (r), r = Su (VST)/Su (TBT) are proposed. All test results are reported and discussed in the paper and conclusions are given.
A solution to the disposal of large volume of dredged sediments is by reuse these materials as fi... more A solution to the disposal of large volume of dredged sediments is by reuse these materials as fills for land reclamation or in road construction. The aim of this study is to identify the influence of fly ash as a binder on the mechanical properties of stabilization of dredged sediment. In order to complete the environmental analysis, mechanical properties are studied in this paper, with usual geotechnical parameters on road construction (particle size analysis, Proctor normal, California bearing ratio, unconfined compressive strength).
For a better environmental practice in the land management of contaminated sediments considered a... more For a better environmental practice in the land management of contaminated sediments considered as waste material, a pilot plant with sediments processing units was installed on a port site near the city of Toulon in the south of France. A large panel of sediments, representative of their variability, has been gathered on this pilot area to be treated and reused. All these processing operations constitute the basis of the SEDI.MAR.D. 83 programme. As part of this programme, one of the objectives concerns the valorisation of marine sediments with hydraulic binders. To succeed in doing that, feasibility tests of stabilization/solidification with raw or pre-treated sediments have been performed. Mechanical and environmental aspects were considered together with the different applied treatments. A lot of tests were run on various port sediments. The obtained results which follow were analyzed and have lead to studying the technical feasibility and ability of the process using hydraulic binders. On one hand, the optimization of the percentages of each binder and additives, if used, was searched for the different mixtures. On the other hand, the environmental acceptability was checked with regards to the enforced regulations, with a view to reusing the treated sediments as material. The considered beneficial uses concern roads and embankments constructions, mainly earthworks, landscaped slopes, fillings of quarries or underground holes. The possible reuses are discussed here and finally, a simple economical approach is proposed taking into account the different ways of treatment applied to the sediments before the stabilization/solidification by binders. This paper is one of a series relative to the
This paper presents a laboratory study which aimed at investigating the soil/pile interaction dur... more This paper presents a laboratory study which aimed at investigating the soil/pile interaction during driving. A short review of past experimental works justifies the need for more consistent data. The test equipment (a rod driven through a sample of soil) is briefly presented and some signals are displayed to illustrate the quality of the measurements. The tests were performed on samples of normally consolidated Kaolinit clay. The analysis of the stress waves propagating in the rod, during driving, provided a good estimation of interaction forces, bar velocities and displacements of the pile model in the sample. Relationships were established between the interaction force, the energy dissipated in the sample of soil, the velocity and the displacement of the rod, and the confining pressure of the sample. Observations and relationships were used ( 1) to identify the physical phenomena occuring at the soil/pile interface during driving, and (2) to base a law governing this shaft interaction.
Les sédiments de l’Usumacinta : réalités du terrain et prélèvements
HAL (Le Centre pour la Communication Scientifique Directe), Jun 4, 2018
La réalisation de travaux de génie maritime et portuaire et la conservation des profondeurs de na... more La réalisation de travaux de génie maritime et portuaire et la conservation des profondeurs de navigation dans les voies d'accès maritimes, des canaux et des fleuves ou des hauteurs d'eau de production dans les retenues hydroélectriques sont des opérations indispensables pour l'économie, l'environnement et le développement d'un pays et/une région. Ces opérations génèrent des volumes de sédiments de dragage à teneur en eau élevée. Se posent alors les questions de leur transport et de leur devenir. En effet, d'une part, ils ont des teneurs en eau si élevée qu'ils restent difficilement transportables et d'autre part, toute valorisation ou stockage des sédiments implique de réduire la teneur en eau. Une déshydratation mécanisée en continu répondrait à cette attente. En développant des machines qui permettent de déshydrater en continu (24h/24h), cette technique paraît très avantageuse. Des presses à boues ont été testées pour des sédiments de dragage en laboratoire. Un modèle de presse KDS ® , dérivée du principe de la presse à boues Volute ® a fait l'objet d'essais de faisabilité et d'optimisation. La présente communication porte sur la définition de cet outil de déshydratation, sur la recherche des paramètres fondamentaux et l'analyse de résultats d'essais effectués sur des argiles et sédiments à teneur en eau élevée.
Les opérations de dragage génèrent une importante quantité de sédiments qui seront considérés com... more Les opérations de dragage génèrent une importante quantité de sédiments qui seront considérés comme des déchets pour une gestion à terre. Le domaine du génie civil propose plusieurs applications pour leur réutilisation. Pour la plupart des applications il faut tout d'abord diminuer leur teneur en eau pour les valoriser. Le séchage naturel consiste à éliminer l'eau contenue dans les sédiments par évaporation et drainage. Cette technique est de loin la plus économique et acceptable du point de vue environnemental. Il est intéressant de rechercher, à l'aide des essais en laboratoire, des critères d'aptitude au séchage naturel des sédiments, en vue d'optimiser toute technique de déshydratation. Une synthèse d'essais de laboratoire est présentée. Ces essais ont été entrepris sur plusieurs sédiments marins et de barrage (Cherbourg, Honfleur, Isère, Durance, Rhin). Les moyens mis en oeuvre sont des essais d'égouttage associés à des mesures réalisées (cohésions non drainées C u ) à l'aide d'un fall-cône et d'un scissomètre de laboratoire. Les résultats d'essais ont pu montrer que le séchage dépend du temps, des caractéristiques des sédiments et de la relation de la cohésion non drainée par rapport à la teneur en eau (C u -w).
L'urbanisation croissante du domaine côtier et les changements de climat attendus et les effets i... more L'urbanisation croissante du domaine côtier et les changements de climat attendus et les effets induits, comme par exemple, l'élévation du niveau de la mer, la probabilité de l'intrusion d'eau salée, l'augmentation des orages et des tempêtes etc., et leur interaction avec la population humaine sont susceptibles de dégrader l'environnement de manière complexe. Afin d'avoir un plan efficace de lutte et de réduction du risque, il faut élaborer un plan de surveillance adéquat qui soit possible et économique. L'utilisation des technologies de pénétration au cône (CPT) offre de telles possibilités. L'essai de pénétration au cône a fait beaucoup de progrès durant les dernières quinze anneés et les interprétations des résultats obtenus qui en découlent sont basées sur des principes bien établis. L'incorporation des techniques géophysiques dans les technologies CPT ouvre une nouvelle voie pour caractériser les conditions du sous-sol dans le domaine côtier. Dans cet article, les auteurs passent en revue certaines de ces technologies pour délimiter et déterminer les caractéristiques du sol. Deux études de cas sont présentées. D'une part, on compare les performances de l'instrumentation classique d'un forage avec celles que permet le pénétromètre au cône et d'autre part, on évalue l'apport de la fluorescence induite par laser utilisant les technologies CPT pour détailler entre autres la concentration en hydrocarbures polyaromatiques (HAP) dans les sédiments de portuaires.
Analysis of physical and mechanical characteristics of tropical natural fibers for their use in civil engineering applications
Journal of Natural Fibers
Journal of Composites Science
Natural fibre-reinforced cementitious composites are commonly used as outer construction material... more Natural fibre-reinforced cementitious composites are commonly used as outer construction materials. They usually suffer weather as a result of being expose to various types of climates. In this study, a series of experimental tests were carried out to investigate the deterioration mechanism and mechanical properties of mortars incorporating coconut fibres due to repeated wetting and drying. The results indicated that although the compressive strength was found to increase after the first cycle, both compressive and flexural strengths underwent a significant decrease in the fifth cycle. In addition, at high temperatures, mortar matrixes retain their stable structure, according to the results of TGA analysis. When wetting and drying curing was applied, there was a significant degradation of fibres in the mortar.
XVIIèmes Journées, Chatou
Every year, a large quantity of sediments is dredged from ports, reservoirs and waterways to main... more Every year, a large quantity of sediments is dredged from ports, reservoirs and waterways to maintain the efficiency of these structures. On the other hand, sediments disposal and management are becoming costly due to environmental regulations. Therefore, the reuse of sediments is increasing in different applications. The reuse of dredged sediments in building materials such as earth bricks can provide an eco-friendly alternative to manage and handle these sediments. Earth bricks are manufactured with earth and natural fibers. This research focuses on the characterization of dredged sediments for their reuse in earth bricks. The sediments used in this study are coming from Dunkerque port and a local dam in France, and Usumacinta River, Mexico. Sediments characteristics such as Atterberg limits, granulometry, carbonate content, organic matter and chemical composition were determined and sediments suitability for earth bricks was observed with French and international standards. Local (hemp shiv) and tropical plant fibers (palm oil fibers) were mixed with sediments to make earth bricks. Impact of sediments granulometry, Atterberg limits and chemical composition on tensile and compressive strength of bricks were analysed. Similarly, tensile and compressive strength variation with fibers addition was also observed. Characteristics of bricks such as density and toughness index and flexion stiffness of bricks were also observed.
Journal of Building Engineering
HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 28, 2022
Des murs en maçonnerie sont construits de briques élaborées avec des sédiments du fleuve Usumacin... more Des murs en maçonnerie sont construits de briques élaborées avec des sédiments du fleuve Usumacinta, du Mexique. Trois types de briques sont fabriqués : i) des briques cuites, ii) des briques stabilisées à la chaux, et iii) des briques crues renforcées par des fibres. Les caractéristiques mécaniques des matériaux sont mesurées. Les murs ont été sollicités horizontalement dans leur plan, les résultats sont présentés et discutés. ABSTRACT -Masonry walls are constructed of bricks made from sediments from the Usumacinta River in Mexico, collected at three different sites. Three types of bricks are manufactured: i) fired bricks, ii) lime-stabilised bricks, and iii) bio-based bricks reinforced with oil palm fibres. The mechanical characteristics of the materials used are measured. The walls were loaded horizontally in their plane, the results are presented and discussed.
Mobility of trace metals and microbiological pollution from dredged sediments to the Gulf of Gabes, Tunisia
Environmental Monitoring and Assessment
Uses of Usumacinta River sediments as a sustainable resource for unpaved roads: An experimental study on a full-scale pilot unit
Transportation Engineering
Sediment-based fired brick strength optimization : A discussion on different approaches
Sustainable sediment management is a global issue due to dredging of rivers and river mouths for ... more Sustainable sediment management is a global issue due to dredging of rivers and river mouths for navigability and flood protection. Previous studies on sediments beneficial uses have shown that essentially the targeted materials relate to roads and ceramics (bricks, tiles). For sustainable management, these recovery sectors impose the minimization of transport and the restriction of the use of binders with a high carbon footprint and addition materials in mixtures (renewable resources). Ceramics for construction appears to constitute a direct recovery method for dredged sediments. Although it requires adequate water content for manufacturing, it does not require any addition of material. However, mixtures of sediments can be operated to improve the chemical composition before firing (optimization). Waste as aggregates (foundry and pickling sand, silica fume, crushed brick, ...) can be incorporated in such mixtures (ecofriendly recovery). Different approaches are available to ensure ...
Natural Fiber [Working Title]
This chapter deals with the reuse and recycling of tropical natural fibers and their potential va... more This chapter deals with the reuse and recycling of tropical natural fibers and their potential valorization in construction materials in a context of circular economy and sustainable development. These fibers constitute large volumes of fibrous waste resulting from various agro-food industries worldwide. Depending on their intrinsic qualities and properties (physical and mechanical), they can be reused as reinforcing material in cementitious mixes (hardened mixes) or mixes with soils (raw mixes) and molded into a prismatic brick-like shape. These bricks constitute construction materials that have mechanical and other characteristics. A whole methodology specific to the development of such materials and their optimization is presented. It includes the preparation, characterization, cutting of the fibers to the desired length and the making of the mixtures. This is followed by optimization (fibers distribution), control and quality of the fiber-reinforced material. Two examples illust...
Reuse of harbour and river dredged sediments in adobe bricks
Cleaner Materials, 2022
Influence of Palm Oil Fibers Length Variation on Mechanical Properties of Reinforced Crude Bricks
Construction Technologies and Architecture, 2022
Crude bricks are composite materials manufactured with sediments and natural fibers. Natural fibe... more Crude bricks are composite materials manufactured with sediments and natural fibers. Natural fibers are waste materials and used in construction materials for reinforcement. Their reuse in manufacturing reinforced crude bricks is eco-friendly and improves mechanical and thermal characteristics of crude bricks. Factors such as type of fibers, percentage of fibers, length of fibers and distribution of fibers inside the bricks have significant effect on mechanical, physical and thermal properties of biobased composite materials. It can be observed by tests such as indirect tensile strength, compressive strength for mechanical characteristics, density, shrinkage, color for physical properties, thermal conductivity and resistivity for thermal properties, and inundation test for durability of crude bricks. In this study, mechanical and physical characteristics of crude bricks reinforced with palm oil fibers are investigated and effect of change in percentage and length of fibers is observ...
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Papers by daniel levacher