Rheological study of mudflows at Lianyungang in China

Xu, Jing-yu; Huhe, Aode

doi:10.1016/j.ijsrc.2014.06.002

Cited by 36 publications

(29 citation statements)

References 16 publications

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“…It is clear that the exponential relation holds for a given location only. This is consistent with the exponential increase in yield stress as a function of density found by diluting concentrated mud samples (Xu and Huhe 2016). Other parameters, such as particle size distribution, type of clay, and organic matter of the sample, must Fig.…”

Section: Stress Sweep and Flow Curvessupporting

confidence: 84%

“…Below a shear rate of 20 s −1 , an extensive structural breakdown is observed for all samples followed by the shear stress equilibrium above 20 s −1 . This value can be referred to as the "critical shear rate" that was applied to destroy the structure of the sample as found by Xu and Huhe (2016). By comparing Fig.…”

Section: Experimental Methodsmentioning

confidence: 98%

“…The results showed higher yield stress values for estuarine mud samples compared with the china clay due to the cohesive nature of the samples. Xu and Huhe (2016) presented the rheological studies of estuarine mud at Lianyungang (China) using both steady and dynamic measurements. They reported an exponential increase in the yield stress of mud samples by increasing the volume fraction of particles.…”

Section: Introductionmentioning

confidence: 99%

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Rheological analysis of mud from Port of Hamburg, Germany

2019

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Purpose An innovative way to define navigable fluid mud layers is to make use of their rheological properties, in particular their yield stress. In order to help the development of in situ measurement techniques, it is essential that the key rheological parameters are estimated beforehand. Is there only one yield stress? In which shear rate/shear stress range is yield expected to occur? How is yield stress dependent on depths and locations in the harbor? In order to answer these questions, we investigated the changes in the rheological properties of mud from along the river stream in the Port of Hamburg, Germany, using a recently developed laboratory protocol. Materials and methods In this study, a detailed rheological analysis was carried out on the mud samples collected from different locations and depths of the Port of Hamburg. A variety of rheological tests was performed including: stress sweep tests, flow curves, thixotropic tests, oscillatory amplitude, and frequency sweep tests. Results and discussion The yield stresses of sediments from different locations were significantly dissimilar from each other due to differences in densities and organic matter content. Two yield stresses (termed static and fluidic) were observed for every sample and linearly correlated to each other. The thixotropic studies showed that all mud samples, except from one location, displayed a combination of thixotropic and anti-thixotropic behaviors. The results of frequency sweep tests showed the solid-like character of the sediments within the linear viscoelastic limit. The yield stresses, thixotropy, and moduli of the mud samples increased by going deeper into the sediment bed due to the increase in density of the sediments. Conclusions This study confirmed the applicability of the recently developed protocol as a fast and reliable tool to measure the yield stresses of sediments from different locations and depths in the Port of Hamburg. The fluid mud layer, in all the locations it was observed, exhibited relatively small yield stress values and weak thixotropic behavior. This confirms that despite the fact that rheology of fluid mud is complex, this layer can be navigable.

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Section: Stress Sweep and Flow Curvessupporting

confidence: 84%

Section: Experimental Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Rheological analysis of mud from Port of Hamburg, Germany

2019

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“…Estuarine mud beds are continuously disturbed by wave motion leading to the formation of different mud layers which can be classified as suspended mud, fluid mud, pre-consolidated/stationary mud and consolidated cohesive bed (Ross and Mehta 1989;Mehta 2013). Fluid mud is usually defined as a fluid having a density within the range of 1030-1300 kg/ m 3 and concentrations about 10-100 g/L, in which settling is considerably hindered by the presence of flocs (Inglis and Allen 1957;Whitehouse et al 2000;McAnally et al 2007). Extensive research has been done on the floc size measurements in the laboratory for muddy sediments (Manning and Dyer 2002;Gratiot and Manning 2004;Manning et al 2007;Spencer et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Is density enough to predict the rheology of natural sediments?

2019

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Mud is a cohesive material which contains predominantly clay minerals, water, organic matter and some amounts of silt and sand. Mud samples can have complex rheological behaviour, displaying viscoelasticity, shear-thinning, thixotropy and yield stress. In this study, influence of organic matter on the rheological behaviour of different mud samples having similar densities is investigated. Four samples, collected from different locations and depths of Port of Hamburg (Germany) were selected. Two samples with the density of about 1210 kg/m 3 and two samples with the density of about 1090 kg/m 3 were analysed by different rheological tests, including stress ramp-up tests, flow curves, thixotropic tests, oscillatory amplitude and frequency sweep tests. Two yield stress regions (with two yield stress values stated as "static" and "fluidic" yield stresses) were identified for all the samples, and these regions, corresponding to a structural change of the samples were significantly different from sample to sample due to the differences in organic matter content. For lower density samples, the ratio of fluidic to static yield stress increased from 3 to 4.4 while it increased from 4.4 to 5.2 in case of higher density samples, by increasing the organic matter content. The thixotropic studies showed that the mud samples having lowest organic matter content (VH and KBZ) exhibit a combination of thixotropic and anti-thixotropic behaviours. The results of frequency sweep tests revealed the solid-like character of the mud within the linear viscoelastic regime. Mud samples having higher organic matter content (RVand RT) had a higher complex modulus (417 Pa and 7909 Pa) than the ones with lower organic matter content (13 Pa and 1774 Pa), for a given density. This study demonstrated that the density only is not a sufficient criterion to predict the rheology of different mud. Furthermore, even small amounts of organic matter content change significantly the mud rheological behaviour.

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“…The following are available online at http://www.mdpi.com/2075-163X/10/11/999/s1, Rheological analysis (i.e., by performing stress ramp-up, frequency sweep and structural recovery tests) and settling behavior of clay suspensions without flocculant as a function of clay concentration. "References [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] are cited in the supplementary materials". Funding: Part of this study was performed as part of the CEAMaS (Civil Engineering Applications of Marine Sediments) project, which was supported by the European Regional Development Funding through INTERREG IV B and the Dutch Technology Foundation STW, which is part of the Netherlands Organisation for Scientific Research (NWO), and which is partly funded by the Ministry of Economic Affairs.…”

Section: Supplementary Materialsmentioning

confidence: 99%

Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis

et al. 2020

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The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on the fact that the clay concentration possible to analyze with selected experimental methods was significantly different. The optimum flocculant to clay ratio was defined as the ratio that gives the fastest initial floc growth by static light scattering or fastest initial settling velocity by settling column experiments. In case of anionic polyelectrolyte, it was observed that the optimum flocculant dose depends on the amount of cations present in the system. For suspensions made with demi-water, a lower optimum flocculant dose (<1 mg/g) than for suspensions prepared in tap water (2.28 mg/g) was observed. At these lower salinities, the supernatant remained turbid in all the experiments and was, therefore, not a good measure for optimal anionic based flocculation. The equilibrium floc size at a given shear rate was found to be independent on the shear history of the floc and only dependent on the current applied shear. This was confirmed by both light scattering and rheological analysis. In case of cationic polyelectrolyte, the optimum flocculant ratio (5–6 mg/g) corresponded to the ratio that gives the lowest electrophoretic mobility for each clay concentration and to the ratio that gives the fastest settling velocity for the highest clay concentrations (12–15 g/L), where static light scattering measurements were not possible. All investigation techniques, therefore, proved to be good indicators for predicting the optimum flocculant to clay ratio. For the lowest concentrations (1.75–8.7 g/L) studied by settling column measurements, the optimum flocculant ratio was observed to increase with decreasing clay concentration, for fixed mixing conditions. The optimum flocculant to clay ratio was not always corresponding to the clearest supernatant and the size of flocs at optimum dosage was dependent on the mixing efficiency. The equilibrium floc size at a given shear rate was found to be dependent on the shear history of the floc and the current applied shear. This was confirmed by both light scattering and rheological analysis.

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Rheological study of mudflows at Lianyungang in China

Cited by 36 publications

References 16 publications

Rheological analysis of mud from Port of Hamburg, Germany

Rheological analysis of mud from Port of Hamburg, Germany

Is density enough to predict the rheology of natural sediments?

Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis

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