Analysis of mixed-sediment consolidation experiments

Type Conference article
Date 2014
Language English
Other localization http://www.paralia.fr/jngcgc/13_39_grasso.pdf
Copyright Editions Paralia CFL
Author(s) Grasso FlorentORCID1, Le Hir Pierre1, Bassoullet Philippe1
Affiliation(s) 1 : Ifremer, Centre de Bretagne, BP 70, 29280 Plouzané, France
Meeting XIIIèmes Journées Nationales Génie Côtier – Génie Civil. Dunkerque, 2-4 juillet 2014
Source XIIIèmes Journée Nationales Génie Côtier - Génie Civil. 2014 Dunkerque. Ed.: D.Levacher, M. Sanchez, A. Hequette et Y. Lalaut. ISBN 978-2-35921-012-5. Thème 2 : Dynamique sédimentaire.pp.353-362
Note DOI 10.5150/jngcgc.2014.039 http://www.paralia.fr/editions/index.php/jngcgc
Keyword(s) Settling column experiments, Consolidation, Sedimentation, Mud/sand mixtures, Sand segregation, Gelling concentration.
Abstract Estuarine sediment transport models require that a time variation of erodibility due to consolidation be taken into account. If numerical modelling of mud sedimentation and consolidation is currently satisfactory, simulation of mud-sand mixture consolidation is more problematical. This is partly due to mixed-sediment processes, as hindered settling and segregation, not well understood yet. Hence, based on extensive settling columns experiments, the aim of this study is to improve our understanding of mud-sand mixture consolidation for varying concentrations (54 to 600 kg/m3) and large sand contents (15
to 80%). Firstly, we observed that for a given initial mass concentration and sand content the final consolidation appeared independent from the initial sediment sample height. For a given initial sand content, the settling phase started earlier for lowconcentrated mixtures and the final consolidation rates ranged between 40 and 90% for high- and low-concentrated mixtures, respectively. Intriguingly, consolidation tests with the lowest initial mass concentrations led to the largest final mass concentrations. A vertical analysis revealed that for high-concentrated sediments the pore water pressure did not fully dissipate, limiting the entire sediment consolidation. In addition, we observed larger final consolidation rates for larger initial sand contents, leading to larger final mass concentrations. Sand segregation was not always observed in our experiments. Interestingly, the initial relative mud concentration appeared as a potential segregation indicator and of interest to estimate the initial gelling concentration. Finally, these experiments represent a rich dataset to validate numerical modelling of mixedsediment settling and consolidation.
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Grasso Florent, Le Hir Pierre, Bassoullet Philippe (2014). Analysis of mixed-sediment consolidation experiments. XIIIèmes Journée Nationales Génie Côtier - Génie Civil. 2014 Dunkerque. Ed.: D.Levacher, M. Sanchez, A. Hequette et Y. Lalaut. ISBN 978-2-35921-012-5. Thème 2 : Dynamique sédimentaire.pp.353-362. http://archimer.ifremer.fr/doc/00206/31727/