Critical Shear Stress for Deposition of Cohesive Sediments in Mai Po

2006 ◽  
Vol 18 (S1) ◽  
pp. 294-299
Author(s):  
W. Y. Chan ◽  
Onyx W. H. Wai ◽  
Y. S. Li
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Cohesive Sediments

Measuring the onset of mine tailings erosion

2007 ◽  
Vol 44 (4) ◽  
pp. 473-489 ◽  
Author(s):  
M Haneef-Mian ◽  
Ernest K Yanful ◽  
Robert Martinuzzi
Keyword(s):  
Shear Stress ◽  
Power Law ◽  
Mine Tailings ◽  
Laser Doppler Anemometry ◽  
Critical Shear Stress ◽  
Laser Doppler ◽  
Shear Stresses ◽  
Cohesive Sediments ◽  
Fine Grained ◽  
Power Law Equation

The present study gives details of a methodology for estimating the critical shear stress for erosion of mine tailings and other naturally occurring cohesive sediments. Erosion of a cohesive sediments bed occurs when the critical shear stress is exceeded to break the interparticle bond. Experiments were conducted in a 30 cm diameter laboratory column and calibrated using laser Doppler anemometry. The results showed that the erosion pattern of mine tailings particles was similar to those of fine-grained cohesive sediments. A power-law relation of the form E = α[(τ – τcr)/τcr]n is suggested for mine tailings, where E is the erosion rate, α is a coefficient, τ is the shear stress, τcr is the critical shear stress, and n is an exponent. The computed values of α, n, and τcr in the power-law equation were found to be comparable to values derived from experiments in a rotating circular flume. The derived expression for rate of erosion may be incorporated in resuspension and transport models for fine mine tailings of a similar nature.Key words: mine tailings, laser Doppler velocimetry, wall shear stresses, critical shear stress for erosion, erosion – shear stress relationship.

Critical Shear Stress for Deposition of Cohesive Sediments in Mai Po

2006 ◽  
Vol 18 (3) ◽  
pp. 300-305 ◽  
Author(s):  
WY CHAN ◽  
Onyx WH WAI ◽  
YS LI
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Cohesive Sediments

scholarly journals Experimental study on incipient condition of fluidized bed sediment in oscillatory

2019 ◽  
Vol 81 ◽  
pp. 01014
Author(s):  
Rui Wang ◽  
Guoliang Yu
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Fluidized Bed ◽  
Oscillatory Flow ◽  
Critical Shear Stress ◽  
Cohesive Sediments ◽  
Bed Sediment ◽  
The Relationship ◽  
Experimental Runs ◽  
Water Contents

In this paper, the incipient condition of the fluidized bed sediment with different sizes and water contents were experimentally studied in an os- cillatory tunnel made of acrylic boards. One-hundred experimental runs were performed with sediment samples by varying the yield stress to determine the relationship between the critical condition of incipient motion and the rheolog- ical properties of the cohesive sediments. Experimental results showed that the yield stress of the bed sediment decreased as the fluidization level increased. When the yield stress is no longer changed, the bed sediment was considered completely fluidized. In oscillatory flow, the critical shear stress decreases with the increase of fluidization level. When the bed sediment reaches the full flu- idization state, the critical shear stress of the bed sediment at the bottom re- mained constant. For cohesive sediments, in the case that particle size and bulk density were known, the relationship between the yield stress and the critical shear stress was analyzed, and the incipient condition of the cohesive sediment under oscillatory flow action was determined.

A data-driven fuzzy approach to simulate the critical shear stress of cohesive sediments

2016 ◽  
pp. 387-393
Author(s):  
A. Schäfer Rodrigues Silva ◽  
M. Noack ◽  
D. Schlabing ◽  
S. Wieprecht
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Data Driven ◽  
Cohesive Sediments ◽  
Fuzzy Approach

scholarly journals The effect of coarse gravel on cohesive sediment entrapment in an annular flume

2015 ◽  
Vol 367 ◽  
pp. 157-162 ◽  
Author(s):  
K. Glasbergen ◽  
M. Stone ◽  
B. Krishnappan ◽  
J. Dixon ◽  
U. Silins
Keyword(s):  
Shear Stress ◽  
Hyporheic Zone ◽  
Critical Shear Stress ◽  
Cohesive Sediment ◽  
Shear Stresses ◽  
Cohesive Sediments ◽  
Gravel Bed ◽  
Gravel Beds ◽  
Annular Flume ◽  
Surface And Pore Water

Abstract. While cohesive sediment generally represents a small fraction (<0.5%) of the total sediment mass stored in gravel-bed rivers, it can strongly influence physical and biogeochemical processes in the hyporheic zone and alter aquatic habitat. This research was conducted to examine mechanisms governing the interaction of cohesive sediments with gravel beds in the Elbow River, Alberta, Canada. A series of erosion and deposition experiments with and without a gravel bed were conducted in a 5-m diameter annular flume. The critical shear stress for deposition and erosion of cohesive sediment without gravel was 0.115 Pa and 0.212 Pa, respectively. In experiments with a gravel bed, cohesive sediment moved from the water column into the gravel bed via the coupling of surface and pore water flow. Once in the gravel bed, cohesive sediments were not mobilized under the maximum applied shear stresses (1.11 Pa) used in the experiment. The gravel bed had an entrapment coefficient (ratio between the entrapment flux and the settling flux) of 0.2. Accordingly, when flow conditions are sufficient to produce a shear stress that will mobilize the armour layer of the gravel bed (>16 Pa), cohesive materials trapped within the gravel bed will be entrained and transported into the Glenmore Reservoir, where sediment-associated nutrients may pose treatment challenges to the drinking water supply.

Modelling Erosion and Deposition of Cohesive Sediments from Hay River, Northwest Territories, Canada

2003 ◽  
Vol 34 (1-2) ◽  
pp. 125-138 ◽  
Author(s):  
David Milburn ◽  
B.G. Krishnappan
Keyword(s):  
Shear Stress ◽  
Northwest Territories ◽  
River Sediment ◽  
Critical Shear Stress ◽  
Cohesive Sediment ◽  
Cohesive Sediments ◽  
Bed Shear Stress ◽  
Flume Experiments ◽  
Annular Flume ◽  
Erosion Processes

A large volume sample of river-bed cohesive sediment and water from Hay River, Northwest Territories, Canada was collected during a spring field program in 2000 as part of a study on under-ice movement of sediment just before breakup. Controlled laboratory experiments were subsequently conducted on the Hay River water/sediments in a rotating annular flume at Burlington, Ontario, Canada to better understand the deposition and erosion processes of cohesive sediment transport. The deposition experiments in the rotating flume confirmed that the Hay River sediment is cohesive and the critical shear stress for deposition and the rates of deposition are a function of bed shear stress and the initial concentration of the sediment in suspension. The erosion experiments provided quantitative data on the critical shear stress for erosion and the rates of erosion as a function of bed shear stress and the age of the sediment deposit. The erosion experiments also indicated that the growth of the biofilm had an influence on the erosion characteristics of the Hay River sediment. Based on the data from the rotating circular flume experiments, a modelling strategy is proposed for calculating the under-ice transport of the cohesive sediments in the Hay River.

A data-driven fuzzy approach to simulate the critical shear stress of mixed cohesive/non-cohesive sediments

2017 ◽  
Vol 18 (10) ◽  
pp. 3070-3081 ◽  
Author(s):  
Aline Schäfer Rodrigues Silva ◽  
Markus Noack ◽  
Dirk Schlabing ◽  
Silke Wieprecht
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Data Driven ◽  
Cohesive Sediments ◽  
Fuzzy Approach

Field evidence of resuspension in a mine tailings pond

2001 ◽  
Vol 38 (4) ◽  
pp. 796-808 ◽  
Author(s):  
Celestina Adu-Wusu ◽  
Ernest K Yanful ◽  
Mohammed H Mian
Keyword(s):  
Shear Stress ◽  
Mine Tailings ◽  
Critical Shear Stress ◽  
Field Measurements ◽  
Shear Stresses ◽  
Wind Speeds ◽  
Tailings Pond ◽  
Field Evidence ◽  
Water Cover ◽  
Solubility Of Oxygen

Flooding of tailings under shallow water covers is an effective method of decommissioning potentially acid generating mine tailings. The low diffusivity and solubility of oxygen in water are attractive features of this technology. However, wind-induced waves can resuspend flooded tailings and expose them to greater contact with dissolved oxygen, thereby increasing the potential for oxidation and acid generation. Field measurements of wind activity and waves under different water cover depths and associated resuspension for a mine tailings pond in Ontario are presented and discussed. The results show that wind speeds greater than 8 m/s above water covers that are shallower than 1 m create waves of height greater than 10 cm and bottom shear stresses greater than 0.2 Pa. Under these conditions the critical shear stress of the mine tailings was exceeded, resulting in erosion and subsequent resuspension.Key words: mine tailings, water cover, wind-induced waves, resuspension, wind speed, shear stress.

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