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A geomechanical approach for the genesis of sediment undulations on the Adriatic shelf - art. no. Q04R03 ArchiMer
Sultan, Nabil; Cattaneo, Antonio; Urgeles, R; Lee, H; Locat, J; Trincardi, F; Berne, Serge; Canals, M; Lafuerza, S.
This study is among the first to examine the genesis of the seafloor and subsurface undulations on the Adriatic continental shelf by integrating stratigraphic information and in situ and laboratory geotechnical measurements. Interpretation of sediment behavior is based on a 32-m-long borehole crossing ( 1) a possible shear plane and ( 2) a silty clay layer at about 20 m below seafloor (mbsf) on which sediment undulations are rooted and could be interpreted as a potential weak layer succession. Our main results in terms of triggering mechanism for the observed undulations show that under an earthquake, liquefaction and/or failure of the silty-clay sediments ( weak layer) leading to deformation of the upper more cohesive sediments is possible only when such...
Tipo: Text Palavras-chave: Sediment deformation; Shear strength; Earthquake; Adriatic shelf.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4105.pdf
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Application of Artificial Neural Network (ANN) in predicting mechanical properties of canola stem under shear loading CIGR Journal
Azadbakht, Mohsen; Torshizi, Mohammad Vahedi; Ziaratban, Armin; Ghajarjazi, Ehsan.
In this study, at first the shear parameters including the maximum shear force, shear strength, shear energy and power consumption of canola stem were calculated through force-deformation curve; and then these mechanical properties were determined and predicted using artificial neural network.   For the tests, testing machine Instron (Model Santam STM-5) with 50 N load cell was used.  Stems were cut at 3 diameter levels (1 to 3, 3 to 5 and more than 5 mm), 3 cutting speed levels (75, 115 and 150 mm/min ), 3 cutting angles (0°, 30° and 60°) and three replicates.   Cutting parameters including maximum cutting force, shear strength; cutting energy; consumed power and cutting work were examined.  Tests lasted for each stem until the full cut.  Data...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Canola; Cutting energy; Stem; Shear strength; Power consumption; Artificial Neural Network (ANN).
Ano: 2016 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3785
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Effect of irrigation regimes and the plant density on shear strength and physical properties of Azivash (Corchorus Olitorius) stem CIGR Journal
Azadbakht, Mohsen; Ghajarjazi, Ehsan; Barzanooni, Esmat; Pourbagher, Roghayeh; Tajari, Neda.
Three irrigation regimes, 6, 12 and 18 days, the distance between seeds in four levels: 5,10, 15 and 20 cm (density, respectively, 80, 40, 27 and 20 plants per m2) and a row spacing of 25 cm was considered that was tested in a randomized complete block design with three replications. The results showed that the effect of irrigation on cutting force, shear strength and energy per unit area was meaningful at 5% level and the effect of plant density on cutting force was meaningful at 1% level, but was not meaningful on shear strength. Also showed interaction between irrigation and plant density on cutting force, shear strength and energy per unit area is not meaningful. It was observed that the effect of irrigation and plant density on the length, diameter...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Azivash; Plant density; Shear strength; Irrigation regime.
Ano: 2015 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/3340
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Evaluation of the risk of marine slope instability: A pseudo-3D approach for application to large areas ArchiMer
Sultan, Nabil; Cochonat, Pierre; Bourillet, Jean-francois; Cayocca, Florence.
This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried...
Tipo: Text Palavras-chave: Shear strength; Slope stability; Safety factor; Marine sediment; Finite element; Finite difference; Failure.
Ano: 2001 URL: http://archimer.ifremer.fr/doc/2001/publication-698.pdf
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Mechanical behaviour of gas-charged fine sediments: model formulation and calibration ArchiMer
Sultan, Nabil; Garziglia, Sebastien.
Multi-phase fluid conditions encountered in geotechnical and geo-environmental problems have led to the development of models that account for the influence of gas solubility and compressibility on the behaviour of soils of various grain sizes. Yet, no consideration has been given to damages related to the nucleation and growth of gas bubbles in fine-grained soils. The purpose of this paper is to present a Cam Clay based constitutive model extended to incorporate such detrimental effects on gassy soils. This is achieved by deriving an analytical expression relating the preconsolidation pressure to a damage parameter dependent on the gas content. That expression is coupled to a deviatoric yield surface accounting for inherent and stress-induced anisotropy....
Tipo: Text Palavras-chave: Compressibility; Constitutive relations; Offshore engineering; Shear strength.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00245/35621/34133.pdf
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Mechanical behaviour of unsaturated marine sediments: experimental and theoretical approaches ArchiMer
Vanoudheusden, Emilie; Sultan, Nabil; Cochonat, Pierre.
The COSTA target areas exhibit different slope failure events, which reflect different triggering mechanisms including gas hydrates dissociation. Gas hydrates stability law depends on temperature, pore pressure, gas chemistry, and pore water salinity. Any change in the equilibrium parameters may convert the hydrate to gas plus water, causing significant weakening of the sediment, and generating a rise of pore pressure. A significant consequence of the hydrate melting is the gas production, which alters significantly the behaviour and mechanical properties of the marine sediments and could be very hazardous when the sediment is unloaded in undrained conditions. The behaviour of the unsaturated marine sediment has to be accurately identified in order to...
Tipo: Text Palavras-chave: Shear strength; Andrained behaviour; Triaxial tests; Capillary pressure; Unsaturated sediment.
Ano: 2004 URL: http://archimer.ifremer.fr/doc/2004/publication-701.pdf
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Prediction of soil shear strength in agricultural and natural environments of the Brazilian Cerrado. Repositório Alice
SILVA, R. B. da; DIAS JUNIOR, M. de S.; IORI, P.; SILVA, F. A. de M.; FOLLE, S. M.; FRANZ, C. A. B.; SOUZA, Z. M. de.
Resumo ? O objetivo deste trabalho foi desenvolver modelos uni e multivariados para estimar a tensão de cisalhamento máxima (tmáx), sob diferentes tensões normais (?n), conteúdos de água (U) e manejos do solo. O estudo foi realizado em Latossolo Vermelho distrófico sob Cerrado (área controle) e sob os sistemas de plantio direto e convencional. Amostras indeformadas foram retiradas na camada de 0,00?0,05 m e submetidas a U e ?n crescentes, durante ensaios de resistência ao cisalhamento. Os modelos uni e multivariados ? respectivamente tmáx=10(a+bU) e tmáx=10(a+bU+csn) ? foram significativos nos três sistemas de manejo do solo avaliados e explicam satisfatoriamente a relação entre U, sn e tmáx. O solo sob Cerrado apresenta a maior tensão de cisalhamento (t)...
Tipo: Artigo em periódico indexado (ALICE) Palavras-chave: Limites de coesão; Interação solo-máquina; Resistência mecânica; Pressão de pré-consolidação; Qualidade física do solo; Compactação do solo; Cerrado; Soil compaction; Soil quality; Shear strength; Savannas; Brazil.
Ano: 2015 URL: http://www.alice.cnptia.embrapa.br/handle/doc/1036303
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Quasi-static and impact cutting behavior definition of privet stem CIGR Journal
Kamandar, Mohammad Reza; Massah, Jafar; Khanali, Majid.
Some of agricultural operations such as privet stem pruning are slowly, repetitive and occasionally dangerous for operators. Almost operators of privet trimmers are exposed to the unpleasant and dangerous arm and body vibrations and sound of pruning machines. The knowing of the shearing behaviors of privet stem have important role in the design and fabricate of suitable pruning machine. So a series of experimental tests were performed to measuring the shear force, shear consumption energy and shear strength of stem internodes of privet stalk under quasi-static and impact cutting at different loading rate, different internode position and moisture level 58% wet base. In the quasi-static cutting test, the stalk specimens were cut in the quasi-static process...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Quasi-static cutting; Impact cutting; Shear energy; Shear strength; Privet.
Ano: 2018 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/4282
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Seafloor instabilities and sediment deformation processes: the need for integrated, multi-disciplinary investigations ArchiMer
Vanneste, Maarten; Sultan, Nabil; Garziglia, Sebastien; Forsberg, Carl Fredrik; L'Heureux, Jean-sebastien.
In this paper, we present the current practice of investigations of seafloor instabilities and deformation processes, based on extensive research conducted over the last years, which sets the scene for future research activities in this field. The mapping of the continental margins and coastal areas with ever increasing resolution systematically reveals evidence of instabilities and deformation processes, both active and palaeo-features. In order to properly assess the hazards and risks related to these features, an integrated and multi-disciplinary approach is essential, but challenging. Such an approach consists of combining field data (geophysics, geology, sedimentology, geochemistry and geotechnical data) with numerical simulations constrained by...
Tipo: Text Palavras-chave: Marine geotechnics; Slope stability; Sediment failures; Fluid flow; Shear strength; Marine geophysics; Monitoring; Excess pore pressure; Site investigations.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00173/28378/26692.pdf
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Sensor based definition of buxus stem shearing behavior in impact cutting process CIGR Journal
Kamandar, Mohammad Reza; Massah, Jafar.
The knowing of the shearing properties of buxus stalk have important role in the design and fabricate of buxus pruning machine. A series of laboratory tests were conducted to measure the shear force, shear consumption energy and shear strength of stem internodes of buxus stalk under impact cutting at four loading rates: 1, 2, 3 and 4 m/s, three internodes: fifth, tenth and fifteenth and moisture content level 72% wet base. In this test, the stalk specimens were served in impact cutting process by using a special cutting test apparatus that was designed, fabricated, and calibrated. To define the impact cutting force of buxus stem, the apparatus was attached with beam type load cell and shear blade. The variance analysis of the data results showed that the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Buxus stem; Impact cutting; Shear energy; Shear force; Shear strength.
Ano: 2018 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/4237
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Une théorie de plaque sandwich ArchiMer
Mace, M.
The objective of this paper is to present a new two-dimensional plate theory inside which a very thin layer is sandwiched. Based upon a prescribed displacement field and a shear stress field fulfilling continuity conditions at the interfaces, this model takes into account the shearing strain due to the high rigidity ratio between the thick skins and the thin film. It is also shown how the present theory was assessed when calculating a rectangular sandwich plate for which Pagano proposed an "exact" three-dimensional solution.
Tipo: Text Palavras-chave: Mathematical models; Strain; Shear strength; Ship technology; Composite materials; Cisaillement; Film mince; Théorie de plaque sandwich; Calculs de structures composites.
Ano: 1992 URL: http://archimer.ifremer.fr/doc/1992/acte-1082.pdf
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Yielding and plastic behaviour of Boom clay ArchiMer
Sultan, Nabil; Cui, Y. -j.; Delage, P..
An underground research laboratory (URL) has been excavated in a deposit of Boom clay at a depth of 223 m by the SCK-CEN Belgian organisation near the city of Mol. This URL is devoted to research into nuclear waste disposal. This paper presents the results of an investigation carried out in the triaxial apparatus on specimens that were trimmed from blocks extracted during excavation sequences in the URL. In order to characterise the mechanical behaviour of the natural Boom clay and to examine the effect of initial and induced anisotropy on its constitutive behaviour, two series of triaxial tests were carried out. Special attention was devoted to the yield behaviour and the effects of stress history. Experimental results showed a clear relation between the...
Tipo: Text Palavras-chave: Anisotropy; Clays; Constitutive relations; Elasticity; Laboratory tests; Plasticity; Shear strength.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00013/12414/9530.pdf
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