Abstract
Dredged slurry is used widely around the world for land reclamation as an important way to alleviate the lack of available land. This method involves hydraulically dredging slurry with extremely high water content to the site where soil is to be formed via sedimentation and consolidation. Therefore, a fundamental understanding of slurry sedimentation, especially in the marine environment, is very important if reclamation construction is to be done securely and economically. This paper investigates slurry sedimentation through laboratory sedimentation tests, considering the effects of the marine environment. It is found that (i) the sedimentation behavior of slurry prepared using seawater is significantly different from that of slurry prepared using distilled water and (ii) other hydrochemical conditions including salt (cation) types and concentrations also affect sedimentation behavior. A sedimentation model is proposed that is capable of quantitative characterization through defining several parameters associated with sedimentation type and sedimentation stabilization. The microscopic mechanism of sedimentation is revealed through scanning electron microscopy and zeta-potential measurements. Although specific to land reclamation construction in Tianjin, China, this study enhances the general understanding of slurry sedimentation affected by hydrochemical environments.
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Some or all data, models, or codes that support the findings of this study are available from the corresponding author upon reasonable request. Data is available upon reasonable request.
Abbreviations
- e 0 :
-
Initial void ratio
- e c :
-
Stable void ratio
- e f :
-
Void ratio at the end of sedimentation test
- e L :
-
Void ratio at liquid limit
- e s :
-
Critical void ratio
- G s :
-
Specific gravity of the slurry
- G w :
-
Specific gravity of water or seawater, = γf/γw
- H 0 :
-
Initial height of slurry
- H c :
-
Height of interface at the end of sedimentation stage
- H t :
-
Height of interface during the sedimentation test
- I p :
-
Plasticity index
- w 0 :
-
Initial water content (corrected considering the effect of salt)
- w 0 * :
-
Critical initial water content
- w f :
-
Water content of sediment at the end of the sedimentation test
- w L :
-
Liquid limit
- w m :
-
Water content in its conventional sense
- w p :
-
Plastic limit
- w t :
-
Water content of sediment during the sedimentation test
- P s :
-
Yield stress of flocs
- S c :
-
Settling of the interface when the consolidation stage starts
- S f :
-
Settling of the interface at the end of the sedimentation test
- S t :
-
Settling of the interface during the sedimentation test
- T :
-
Time
- T c :
-
Sedimentation stable time
- T f :
-
Duration of the flocculation stage
- V f :
-
Settling rate of interface in the flocculation stage
- β :
-
Salt content
- γ f :
-
Unit weight of the salt solution or seawater
- γ s :
-
Unit weight of soil particle
- γ w :
-
Unit weight of pure water
- γʹs :
-
Unit weight of sediment
- ζ :
-
Zeta potential
- ρ d :
-
Dry density
- σʹ:
-
Effective stress
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Acknowledgements
The authors are grateful for the constructive suggestions from editors and reviewers.
Funding
The financial supports from the National Natural Science Foundation of China (Nos. 41972285, 41972293, 52178372), the Youth Innovation Promotion Association CAS (Grant No. 2018363), and Science Fund for Distinguished Young Scholars of Hubei Province (2020CFA103) are thanked.
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Writing—original draft preparation: Xianwei Zhang, Xinyu Liu, Wei Zhang. Writing—review and editing: Xianwei Zhang, Xinyu Liu, Aiwu Yang. Data collection and analysis: Xianwei Zhang, Xinyu Liu, Yiqing Xu. Methodology: Xianwei Zhang, Xinyu Liu, Wei Zhang.
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Zhang, X., Liu, X., Zhang, W. et al. Sedimentation of the fine-grained dredged slurry in the marine environment. Bull Eng Geol Environ 81, 173 (2022). https://doi.org/10.1007/s10064-022-02680-5
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DOI: https://doi.org/10.1007/s10064-022-02680-5