Revue Paralia最新文献

{"title":"NOTA TÉCNICA - Reparación del emisario de Las Palmas de Gran Canaria. Parte I: descripción de los trabajos","authors":"J. Aguirre, María D. Afonso Correa","doi":"10.5150/REVUE-PARALIA.2012.006","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.006","url":null,"abstract":"La reparacion del emisario de Las Palmas de Gran Canaria representa un ejemplo de escuelacomo por la realizacion de la reparacion. Por diferentes motivos hasta ahora la construccion de emisarios ha sido considerada una actuacion de segunda clase y por ello ha sido siempre una obra disenada y ejecutada con muy poca atencion. Esta actitud unida a la deficiencia cronica en la depuracion de aguas residuales e industriales, da como resultado que las aguas costeras espanolas y europeas sufran una continua presion de vertidos con una muy deficiente depuracion y con una minima dilucion. En esta nota tecnica primero se describen las deficiencias del emisario estudiado, las soluciones posibles para su reparacion y una descripcion de la solucion adoptada para la reparacion parcial prevista sin incluir el tramo difusor. Poco antes de concluir la reparacion parcial, se presento un estudio sobre la conveniencia de completar la reparacion incluyendo el tramo difusor. En este estudio se justifico la conveniencia de la reparacion del tramo difusor con un trabajo de simulaciones numericas (que vendra descrito en la parte II de esta nota tecnica), que convencio a la administracion para ampliar el presupuesto de la ejecucion de la obra. Version traduite : NOTE TECHNIQUE - Reparation de l’emissaire de Las Palmas de Gran Canaria. Partie I : description des travaux La reparation de l’emissaire de Las Palmas de Gran Canaria est un cas d’ecole pour l’ingenierie de ce type de travaux, autant par ses defauts au moment de sa construction que pour la realisation de sa reparation. Pour plusieurs raisons jusqu’a maintenant, la construction d’emissaires a ete consideree comme une activite secondaire et pour cela la conception et l’execution ont ete menees avec tres peu d’attention. Ce constat, ajoute a la deficience chronique de l’epuration des eaux residuelles et industrielles, fait que les eaux cotieres espagnoles et europeennes souffrent de la presence continue de dechets avec une epuration tres inefficace et une dilution minimale. Dans cette note technique, nous decrirons d’abord les carences de l’emissaire etudie, puis les solutions possibles pour sa reparation et enfin la solution adoptee pour la reparation partielle prevue, qui n’inclut de troncon diffuseur. La reparation partielle etant maintenant en cours, nous avons propose de la completer en y incluant un troncon diffuseur. Tout l’interet de la reparation avec ce dernier element a ete justifie a l’aide d’une simulation numerique, qui est decrite dans la partie II de cette note technique. Ce complement d’etude numerique a permis de convaincre l’administration et a contribue a l’augmentation du budget pour l’execution du chantier. Mots-cles : Emissaire; Travaux sous-marins; Reparation; Las Palmas de Gran Canaria.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126852477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Le complexe lagunaire de Nador (Maroc) : fonctionnement, contrôle naturel et provoqué, scenarii d’évolution future","authors":"N. Hamoumi","doi":"10.5150/REVUE-PARALIA.2012.005","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.005","url":null,"abstract":"Le complexe lagunaire de Nador situe dans le littoral mediterraneen oriental (Maroc), presente un interet scientifique et socio-economique. L’etude de toutes les composantes de ce complexe lagunaire (masse d’eau, sediments, microfaune) et de tous ses domaines physiographiques ainsi que de son bassin versant et du proche plateau continental, a ete menee a l’aide de techniques variees dans differents champs disciplinaires : geomorphologie et morphodynamique (basee sur l’etude de terrain et l’analyse d’images satellitaires sur une periode de 34 ans), etude morphostructurale, sedimentologie, ecologie et qualite de l’eau. Les resultats qui sont pour la plupart nouveaux et originaux, ont permis de comprendre le mode de genese et de fonctionnement du complexe lagunaire et de mettre en evidence des evolutions d’ordre spatial et temporel a une echelle saisonniere et a l’echelle du millenaire. Ces evolutions sont liees a des facteurs naturels qui peuvent agir independamment ou de concert et a des facteurs anthropiques. L’analyse de l’impact des facteurs naturels a permis de predire sept scenarii d’evolution future pour cet ecosysteme. En plus de leur interet scientifique, les resultats obtenus ainsi que les nombreuses cartes thematiques et les cartes SITO etablies constituent une base de donnees importante et un outil de decision pour les amenagements de la region. Par ailleurs, la demarche proposee pour cette etude constitue un outil pratique pour l’exploitation et l’amenagement des ecosystemes littoraux en general et lagunaires en particulier. Translated version: The Nador barrier island system (Morocco): functioning, natural and man-induced controls, scenarios of future evolutions The Nador barrier island system located on the Eastern Mediterranean coast of Morocco is an ecosystem of scientific and socioeconomic interest. The study of all its components (water mass, sediment, microfauna) and physiographic domains, as well as its hinterland and the close continental shelf, was conducted using various disciplines and techniques: geomorphology and morphodynamics (field study and analysis of satellite images over a period of 34 years), morphostructural analysis, sedimentology, ecology and water quality. The results which are mostly new and unique allowed understanding of the mode of the genesis and functioning of this lagoon system and highlighted the spatial and temporal evolutions at a seasonal and millennium scales. These evolutions are related to anthropogenic as well as natural factors which can act independently or simultaneously. The analysis of the effects of natural factors impacts helped to predict seven possible scenarios of future evolutions of this ecosystem. In addition to their scientific interest, the results obtained as well as the generated thematic maps and the Territorial Information System (SIT) maps, constitute an important database and a fundamental decision-making tool for an adequate management and development of the region. Further","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126354970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elaboration et test d’indicateurs de suivi des initiatives locales de gestion intégrée du littoral méditerranéen","authors":"A. Lafitte, J. Denis, Y. Hénocque, B. Andral, Pierre Boissery","doi":"10.5150/REVUE-PARALIA.2012.004","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.004","url":null,"abstract":"L’evaluation des politiques publiques appliquees a la gestion du littoral releve d’approches relativement recentes. La directive europeenne sur l’evaluation strategique environnementale (ESE) a ete transposee en droit francais en 2001, au cours de laquelle le legislateur a insiste sur la necessite de disposer d’outils destines a evaluer des demarches de gestion. Cet article aborde ce sujet en presentant le developpement d’une methode d’evaluation des dynamiques de gestion sur le littoral. Cette methode prend appui sur les differentes dimensions de l’integration a laquelle recourt la gestion integree des zones cotieres. Ainsi, les six indicateurs qui la caracterisent renseignent sur (i) l’approche multi-usage, (ii) la coordination inter-institutionnelle, (iii) l’utilisation a bon escient des connaissances, (iv) l’approche multi-echelle, (v) la participation des acteurs et (vi) la prise en compte de la durabilite. L’approche methodologique ainsi adoptee a ete testee sur cinq sites du littoral mediterraneen francais, aupres de cinq groupes d’acteurs representant (i) les services de l’Etat, (ii) les gestionnaires locaux, (iii) les professionnels du secteur prive, (iv) la societe civile et (v) les experts scientifiques. Translated version: Elaboration and test of indicators for monitoring the local Mediterranean coast initiatives concerning integrated manageme The evaluation of public policies applied to shoreline management is a relatively new approach. The European Directive of Strategic Environmental Assessment (SEA) was transposed into French law in 2001, during which the legislator has stressed the need to put the tools into place to evaluate management approaches. The article addresses this topic by presenting the development of a method for evaluating the dynamic management of the coast. This method, taking support on different dimensions of integration, is used by the integrated management of the coastal zones. Thus, the six indicators that characterize it provide information on (i) the multi-purpose approach, (ii) the inter-institutional coordination, (iii) the proper use of knowledge, (iv) the multi-scale approach, (v) the stakeholder participation, and (vi) the taking into account of sustainability. Hence, the methodology approach was adopted and tested in five sites of the Mediterranean French coast, with five groups of stakeholders representing (i) the services of the State, (ii) the local administrations, (iii) the professionals from the private sector, (iv) the civil society and (v) the scientific experts. Besides the results, this article focuses on the methods to develop and implement such approach and discusses its advantages and limits of application regarding a possible generalization to other cases on the coast. Keywords: ICZM; Indicators; Environmental Assessment; Group of Stakeholders.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128916742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring temps reel haute resolution d'un littoral: MAGOBS (Villeneuve-les-Maguelone, Golfe du Lion, France)","authors":"Bénédicte Guerinel, F. Bouchette, Olivier Lobry, D. Astruc, P. Azerad, E. Brambilla, R. Certain, P. Larroudé, M. A. Manna, Samuel Meulé, V. Rey, N. Robin, F. Sabatier, Damien Sous, David Martinie, Nicolas Arnaud","doi":"10.5150/JNGCGC.2012.064-G","DOIUrl":"https://doi.org/10.5150/JNGCGC.2012.064-G","url":null,"abstract":"Le lido de Villeneuve-les-Maguelone (Languedoc-Roussillon) est un archetype de littoral microtidal, domine par la houle, en erosion, et largement affecte par la submersion marine lors des tempetes. Les observations realisees dans le cadre du Systeme d'Observation Littoral - Trait de Cote (SO LTC) concernent l'hydrodynamique et le transport sedimentaire dans l'avant-cote et la lagune. La tache d'observation MAGOBS (Observatoire Aresquiers-Maguelone-Palavas) de cet observatoire regroupe un dispositif instrumental automatise compose de 30 points d'acquisition en temps reel entre 6 metres de profondeur et le haut de plage (a terre) ainsi que dans la lagune. Le dispositif est operationnel depuis mai 2011. Son deploiement a permis de deverrouiller les difficultes techniques liees a la mesure temps reel en zone littorale : choix du type des appareils de mesure, de la technologie embarquee, des cadences d'acquisition, resolution des questions du transfert de la donnee. Le dispositif produit 2 Tera-octets de donnees par an. Les donnees sont stockees sur un ensemble de serveurs dedies. Les donnees sont mises en ligne sur le site du SO-LTC (www.soltc.org), immediatement apres premiers traitements et qualification. Elles commencent a etre utilisees pour des calculs de niveau d'eau a la cote, et dansdes outils de prediction des vagues et des niveaux a la cote associant mesure et modelisation.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126064040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upper beach reconstruction patternsafter moderate storm events","authors":"Lucie Campmas, F. Bouchette, Jiing-Yih Liou, E. Brambilla, S. Meulé, G. Sylaios, F. Sabatier, R. Certain, N. Robin, H. Hwung","doi":"10.5150/JNGCGC.2012.023-C","DOIUrl":"https://doi.org/10.5150/JNGCGC.2012.023-C","url":null,"abstract":"The wave-dominated beach barrier of Villeneuve-Les-Maguelone extends between Palavas and Frontignan (Gul f of Lions, northernmost Me diterranean Sea), along a slightly natural sandy protected area char acterized by typical and well-expressed morphologies. In the nearshore, the sea bottom shows one or two approximately rectilinear sand bars. In 2010-2011, we pe rformed a 6 month-long monitoring (autumn 2010/late spring 2011) of a 500 meter-long se gment along this sand barrier. We used RTK D-GPS offering centimeter resolution to acquire sets of elevation data on the beach and the upper shoreface. The study is innovative because a full morphologic monitoring was performed each time the wave/ wind conditions changed significantly. These changes were tracked in real-time thanks to a set of hydrodynamic equipments deployed at sea, including well-known DREAL buoys. We identify from well- documented data: (1) a beach reconstruction cycle at the shorelin e after a moderate storm event (wave height at 3-4 m) and (2) how a sand bar in the nearshore migrates to the shoreline and drives the shoreline shift.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117001114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SUBDUNE tool: quasi-explicit formulation of the water level along the shoreline","authors":"F. Bouchette, F. Sabatier, G. Sylaios, S. Meulé, Jying-Yi Liou, H. Heurtefeux, C. Denamiel, H. Hwung","doi":"10.5150/JNGCGC.2012.022-B","DOIUrl":"https://doi.org/10.5150/JNGCGC.2012.022-B","url":null,"abstract":"SUBDUNE v0.6 is a very preliminary version of an exploratory model designed to compute the sea level to the shoreline, combining the effects of various physics, from run-up to tides. It aims at providing an easy-to-use and quick way to estimate water elevation to the beach, assuming morphology is known. Combined with accurate beach data, such as LIDAR, this engineering tool may provide with end-users an efficient way to quantify submersion.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133792433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shoreline and upper beach dynamics under extreme events: the KUNSHEN experiment (Wan Tzu Liao barrier, Taiwan)","authors":"S. Meulé, Lucie Campmas, F. Bouchette, Jiing-Yih Liou, F. Sabatier, D. Sous, G. Sylaios, V. Rey, Ying-Chih Wu, Tsung-Yih Lin, H. Hwung","doi":"10.5150/JNGCGC.2012.034-M","DOIUrl":"https://doi.org/10.5150/JNGCGC.2012.034-M","url":null,"abstract":"Barrier island hydro-morphodynamics driven by typhoon events are the major concern of the project KUNSHEN (2011-2014). It aims at providing for a deep understanding of the peculiar dynamics of sand barriers where extreme events such as typhoons have a significant impact. We present the campaigns and the protocols achieved and planned in the project, on the Wan-tzu-liao sand barrier, Cigu Lagoon, Tainan, Taiwan, from October 2011 to January 2012, during the winter storm season and during summer 2012 during the typhoon season. A set of current profilers are deployed along a cross shore transect at 7, 4 and 2 meters deep. On the Wan-tzu-liao sand barrier, 3 columns of 3 pressiometers are deployed to survey the submersion. In the same time, morphological surveys are performed on the sand barrier with DGPS to analyse any change in the shoreline position, the beach slope, and the dynamics of sand beach features. A very preliminary analysis on these on-going field surveys suggests that the word \"extreme\" refers more to the consequence of the forcing on the sand barrier than the intensity of the forcing itself. The strategy developed in this first step will be refined to survey the next typhoon season, from May 2012 to October 2012.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130460873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analyse statistique des données obtenues sur les sédiments traités sur le site pilote de SEDI.MAR.D 83","authors":"C. Benoit, F. Saby, J. Turlot, O. Donard","doi":"10.5150/REVUE-PARALIA.2012.003","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.003","url":null,"abstract":"Le projet SEDI.MAR.D 83 avait pour objectif de proposer differentes techniques de traitements afin d’optimiser la gestion a terre de sediments marins dragues provenant de ports mediterraneens. Dans ce but, une caracterisation physico-chimique des sediments a ete realisee sur l’echantillon brut initial mais egalement a la fin de chaque traitement applique. Une base de donnees importante a ainsi ete obtenue pour differents contaminants ainsi que des donnees complementaires sur les proprietes physiques et les nutriments. L’objectif de ce travail est d’utiliser des outils statistiques pour hierarchiser les differentes filieres de traitement et etablir des correlations entre les differents parametres geochimiques. Il a ete montre que deux ports (Arsenal et Guilvinec) se distinguent des autres ports par une pollution importante. Parmi les differents traitements appliques, le compostage s’avere particulierement interessant pour les composes organiques et les composes organometalliques. Pour ces memes composes, le traitement par calcination engendre egalement un abattement des concentrations. En revanche, pour les metaux comme le cuivre, aucun traitement n’apparait presenter un effet positif sur la decontamination. Par contre, la phosphatation et la calcination (procede NOVOSOL®) semblent favoriser l’inertage du sediment par piegeage du cuivre dans la masse sedimentaire.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131096770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Approche méthodologique pour la validation environnementale d’un projet de remblaiement de cavités terrestres de la zone littorale à l’aide de sédiments de dragage de ports maritimes traités","authors":"Y. Perrodin, R. Moretto","doi":"10.5150/REVUE-PARALIA.2012.002","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.002","url":null,"abstract":"Les sediments de dragage des ports maritimes non rejetables en mer en raison de leur forte pollution posent un probleme de gestion dans la mesure ou les filieres terrestres classiques (incineration, mise en decharge,…) ne sont adaptees a leur traitement, ni sur le plan economique, ni sur le plan des volumes absorbables. Parmi les solutions de substitution envisagees, le remblaiement de carrieres seches represente une filiere prometteuse, notamment parce qu’elle offre des capacites suffisantes pour gerer de tels volumes. Cette filiere necessitait toutefois d’engager un programme de recherche visant a proposer une methodologie d’evaluation des risques ecologiques specifique, permettant de valider, lors de chaque operation de remblaiement d’envergure, sa compatibilite avec les milieux et les ecosystemes continentaux voisins. Dans ce contexte, l’objectif du programme ANR SEDIGEST etait double : (i) sur le plan operationnel : developper une methodologie d’evaluation des risques ecologiques adaptee au scenario de gestion precedemment evoque, (ii) sur le plan scientifique : lever les principaux verrous qui s’opposaient a la redaction d’une telle methodologie, et qui etaient, pour l’essentiel, lies a une comprehension encore tres partielle des differents mecanismes physiques, chimiques et biologiques qui interviennent lors de leur depot a terre. Apres trois annees de travaux, portant sur trois matrices sedimentaires originaires de ports maritimes du sud et de l’ouest de la France (deux du Var et un du Finistere), le programme SEDIGEST a abouti a une proposition methodologique, comprenant quatre niveaux de complexite possibles, utilisable pour la validation environnementale d’un projet donne de remblaiement de cavites terrestres a l’aide de sediments de dragage portuaires. Translated version: Methodological approach for the environmental validation of a quarry fill in a coastal area using treated dredged seaport sediments Heavily polluted dredged seaport sediments cannot be dumped into the sea and thus raise problems regarding their management since classical terrestrial methods (incineration, depositing in dumps, etc.) are ill-adapted to their treatment, both economically and with respect to the volumes that can be absorbed. Among the alternative solutions considered, filling in dry quarries appears promising, in particular because it provides sufficient capacities for managing the large volumes involved. This method nonetheless requires launching a research program aimed at providing a methodology for assessing specific ecological risks, in order to validate the compatibility of each large-scale filling operation with neighbouring inland environments and ecosystems. In this context, the objective of the ANR SEDIGEST program was twofold: (i) operationally: to develop an ecological risk assessment methodology adapted to the management scenario mentioned above, (ii) scientifically: to remove the main barriers against drawing up such a methodology. These we","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133932850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Etude rhéométrique pour la mise au point de sédiments cohésifs modèles transparents pour une approche locale du comportement en érosion","authors":"Keang Sè Pouv, A. Besq, S. Guillou","doi":"10.5150/REVUE-PARALIA.2012.001","DOIUrl":"https://doi.org/10.5150/REVUE-PARALIA.2012.001","url":null,"abstract":"Dans cette contribution, on a recourt a des essais rheometriques pour caracteriser le comportement d’un sediment cohesif naturel dont une partie est traitee par rayonnement ionisant gamma. On montre que ce traitement conduit a une reduction importante du niveau de resistance du sediment. Le suivi specifique des dynamiques d’evolution de la structure du sediment permet d’etablir des relations d’echelle. Le vieillissement au repos met en evidence une loi d’evolution en puissance du temps. L’observation de la transition solide/liquide (processus similaire a l’erosion du fond sedimentaire) permet d’obtenir une relation exponentielle du temps de transition en fonction de l’inverse de la contrainte appliquee. Le fait le plus remarquable est que les dynamiques ne semblent pas affectees par le traitement par irradiation gamma. Pour mieux comprendre les phenomenes mis en jeu dans le processus d’erosion, il est propose de suivre localement ces dynamiques a l’aide des techniques PTV et LIF. Dans cette optique, il faut disposer de fluides modeles transparents simulant les proprietes rheologiques des sediments naturels et notamment les dynamiques particulieres presentees precedemment. Deux fluides modeles a seuil (gels) utilisant le carbopol et la laponite sont ainsi mis au point, et on montre la similitude des proprietes. Translated version: Rheometric study for elaborating transparent model of cohesive sediments for local investigations of erosion behaviour In this paper, the behaviour of cohesive sediments is studied using rheometric experiments. Results have shown that the treatment of natural sediments using gamma irradiation leads to an important reduction of their original mechanical strengths. The dynamics of evolution of sediment structure during ageing gives rise to a characteristic time written as a power law of the rest period. The observation of the solid/liquid transition (similar process to the erosion of sedimentary bed) allows us to obtain an exponential law of the inverse of applied shear stress. It is very unlikely that these dynamics are affected by gamma irradiation treatment. For better understanding of the phenomena regarding the erosion process, it is suggested to study these dynamics locally by using PTV and LIF techniques. These optical techniques require the use of transparent model materials having very similar rheological properties to those of natural sediments. Two yield stress fluids (gels) that have been specifically prepared using carbopol and laponite are proposed within this framework. Keywords: Solid/liquid transition; Erosion; Thixotropy; Yield stress; Cohesive sediments; Model fluids.","PeriodicalId":202784,"journal":{"name":"Revue Paralia","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134452510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}