Laboratory investigation on erosion threshold shear stress of cohesive sediment in Karkheh Dam

2021 ◽  
Vol 80 (19) ◽  
Author(s):  
Rouhallah Fatahi Nafchi ◽  
Hossein Samadi-Boroujeni ◽  
Hamid Raeisi Vanani ◽  
Kaveh Ostad-Ali-Askari ◽  
Milad Khastar Brojeni
Keyword(s):  
Shear Stress ◽  
Laboratory Investigation ◽  
Cohesive Sediment ◽  
Erosion Threshold

scholarly journals Experimental Study of Erosion Threshold of Reconstituted Sediments

2011 ◽  
Author(s):  
Zhihui Ye ◽  
Liang Cheng ◽  
Zhipeng Zang
Keyword(s):  
Shear Stress ◽  
Steady Increase ◽  
Initial Increase ◽  
Threshold Condition ◽  
Seabed Sediment ◽  
Erosion Threshold ◽  
Sediment Types ◽  
Weight Content ◽  
Testing Facility ◽  
Seabed Sediments

Understanding of fundamental erosion characteristics of seabed sediments on which pipelines and other structures are founded is critical for the design of these facilities. The erosion threshold condition of cohesive sediments is not well understood because of the complexity and variability of natural sediments. Most of the existing methods for evaluating the erosion behaviours of seabed sediment are often applicable to the certain particular sediment types and test conditions. There appears to be a need for more research efforts in this area. In present research, the threshold of motion of four moderately consolidated mixtures was tested under unidirectional currents using a testing facility. Three threshold shear stress increase modes were observed, including initial increase mode, steady increase mode and equilibrium mode as mass content of mud Pm increases. A dimensionless threshold shear stress τ* is proposed to quantify the shear strength of these reconstituted mixtures, coupled with variation of coarse particle size. Finally, a predicting model is proposed to illustrate the trend of erosion threshold of the four mixtures as a function of mud weight content. Further understanding of erosion threshold can rely on the various consolidation conditions and different coarse and fine materials inputted in the mixture.

scholarly journals The effect of cyclic variation of shear stress on non‐cohesive sediment stabilization by microbial biofilms: the role of ‘biofilm precursors’

2019 ◽  
Vol 44 (7) ◽  
pp. 1471-1481 ◽  
Author(s):  
Xindi Chen ◽  
Changkuan Zhang ◽  
David M. Paterson ◽  
Ian H. Townend ◽  
Chuang Jin ◽  
...  
Keyword(s):  
Shear Stress ◽  
Cohesive Sediment ◽  
Cyclic Variation ◽  
Microbial Biofilms ◽  
Sediment Stabilization

Critical Bed-Shear Stress for Cohesive Sediment Deposition under Steady Flows

2008 ◽  
Vol 134 (12) ◽  
pp. 1767-1771 ◽  
Author(s):  
Jerome Peng-Yea Maa ◽  
Jae-Il Kwon ◽  
Kyu-Nam Hwang ◽  
Ho-Kyung Ha
Keyword(s):  
Shear Stress ◽  
Cohesive Sediment ◽  
Sediment Deposition ◽  
Bed Shear Stress ◽  
Steady Flows

Mechanical and Chemical Stabilisation of Carbonatesand

2013 ◽  
Vol 742 ◽  
pp. 224-230
Author(s):  
Khaled Grine
Keyword(s):  
Shear Stress ◽  
Laboratory Investigation ◽  
Silica Sand ◽  
Carbonate Sand ◽  
Stress Strain ◽  
Volumetric Change ◽  
Isotropic Compression ◽  
Compressibility Characteristics

This paper describe a laboratory investigation into the effects of adding silica sand and/or cement on the behaviour of artificial carbonate sand under shear and compression. Drained shear and compressibility tests have been performed on artificial carbonate sand samples and artificial carbonate sand samples mixed with different proportion by weight of silica sand and/or cement in order to determine the shear stress-strain and compressibility characteristics of the mixed material.The results demonstrate that contraction during shear and compressibility during isotropic compression decrease as the fraction of silica sand and/or cement increases within the artificial carbonate sand.A positive volumetric change (dilation) during shear is more obvious with cemented samples. It also demonstrate how the addition of a combination of silica sand and cement produces the most effective improvement in terms of strength, stiffness, compressibility and crushing.

The effects of tidally-driven temporal variation on measuring intertidal cohesive sediment erosion threshold

2005 ◽  
Vol 40 (4) ◽  
pp. 521-531 ◽  
Author(s):  
T.J. Tolhurst ◽  
E.C. Defew ◽  
R.G. Perkins ◽  
A. Sharples ◽  
D.M. Paterson
Keyword(s):  
Temporal Variation ◽  
Cohesive Sediment ◽  
Sediment Erosion ◽  
Erosion Threshold ◽  
Tidally Driven

Laboratory investigation on the effects of flushes on cohesive sediment beds

2008 ◽  
Vol 5 (1) ◽  
pp. 3-14 ◽  
Author(s):  
A. Campisano ◽  
E. Creaco ◽  
C. Modica
Keyword(s):  
Laboratory Investigation ◽  
Cohesive Sediment

scholarly journals Experimental study on incipient shear stress of consolidated cohesive sediment

2020 ◽  
Vol 13 (18) ◽  
Author(s):  
Caiwen Shu ◽  
Guangming Tan ◽  
Peng Chen ◽  
Jun Wang ◽  
Ping Lv
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Bulk Density ◽  
Cohesive Sediment ◽  
Experimental Results ◽  
Incipient Motion ◽  
Motion Mechanism ◽  
Cohesive Particles ◽  
Sediment Mixtures ◽  
Consolidation Time

Abstract This paper analyzes the incipient motion mechanism of consolidated cohesive sediment. An experimental device based on previous studies was designed to investigate the influencing factors of the incipient shear stress, including the consolidation time, the density of dry bulk, cohesive particles content, and the composition of sediment mixtures. The experimental results indicated that the incipient shear stress of cohesive sediment increased with the increase of consolidation time, dry bulk density, and content of cohesive particles. The incipient motion mechanism of cohesive particles was further investigated using experimental data and theoretical analysis. A formula of the incipient shear stress for cohesive sediment was proposed herein, which is related to both the content of cohesive particles and the relative dry bulk density. The proposed formula was validated by the experimental data, and the calculated values of incipient shear stress using the formula were in good agreement with the experimental results.

scholarly journals Experimental Investigation of Erosion Characteristics of Fine-Grained Cohesive Sediments

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1511
Author(s):  
Bommanna Gounder Krishnappan ◽  
Mike Stone ◽  
Steven Granger ◽  
Hari Upadhayay ◽  
Qiang Tang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Shear Stress ◽  
Critical Shear Stress ◽  
River System ◽  
Cohesive Sediment ◽  
Erosion Process ◽  
Fine Grained ◽  
Annular Flume ◽  
Two Factors ◽  
Sediment Deposit

In this short communication, the erosion process of the fine, cohesive sediment collected from the upper River Taw in South West England was studied in a rotating annular flume located in the National Water Research Institute in Burlington, Ontario, Canada. This study is part of a research project that is underway to model the transport of fine sediment and the associated nutrients in that river system. The erosion experimental data show that the critical shear stress for erosion of the upper River Taw sediment is about 0.09 Pa and it did not depend on the age of sediment deposit. The eroded sediment was transported in a flocculated form and the agent of flocculation for the upper River Taw sediment may be due to the presence of fibrils from microorganisms and organic material in the system. The experimental data were analysed using a curve fitting approach of Krone and a mathematical model of cohesive sediment transport in rotating circular flumes developed by Krishnappan. The modelled and measured data were in good agreement. An evaluation of the physical significance of Krone’s fitting coefficients is presented. Variability of the fitting coefficients as a function of bed shear stress and age of sediment deposit indicate the key role these two factors play in the erosion process of fluvial cohesive sediment.

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