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Showing 1 to 20 of 21 for “"critical shear stress"”.
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Changes in Streambank Erodibility and Critical Shear Stress Due to Surface Subaerial Processes
… studies have shown that soil erodibility and critical shear stress are highly influenced by weathering processes such as freeze-thaw cycling and wet-dry cycling. Despite over forty years of research attributing changes in soil properties over time to climate-dependent variables, little …
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Evaluation of an In Situ Measurement Technique for Streambank Critical Shear Stress and Soil Erodibility
… a simple in situ method of measuring streambank critical shear stress (Ï c) and soil erodibility (kd). Previous research showed streambank kd and Ï c can vary by up to four orders of magnitude at a single site; therefore, it is essential to determine if the large range is due to natural …
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Evaluation of the Jet Test Method for determining the erosional properties of Cohesive Soils; A Numerical Approach
… device is an in situ method of determining the critical shear stress and soil erodibility of cohesive soils. A constant velocity jet, applied perpendicular to the soil surface, creates a scour hole which is measured at discrete time intervals. While the results of these tests are able to provide …
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Fundamental study of nucleation and heteroepitaxial thin film growth using ionized source beam
… neutral nozzle beam case. Also, the resulting critical shear stress acting on the interface between the cluster and the substrate showed that the critical shear stress of ionized clusters was one order of magnitude higher than that of neutral clusters. These results indicate that the two …
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The Role of Instantaneous Forces in Particle Movement
… rates, most of which use some comparison between shear stress and critical shear stress. The critical shear stress is determined by the point of incipient motion. Researchers have attempted to predict bed load transport both deterministically with mean parameters and stochastically attempting to …
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Headcut retreat resulting from plunge pool erosion in a 3D landscape evolution model
… the relevant soil parameters (erodibility and critical shear stress). The model was analyzed to study its behavior as its input parameters changed, and its output was compared to experimental observations. Next, the plunge pool mechanism was implemented in an existing 3D landscape evolution …
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Bedload transport: the effects of particle shape and an investigation of a wide range of transport rates
… particles indicates that the reference transport critical shear stress for the median surface grain size is approximately 2 to 3 times higher than those for more spherical particles. This conclusion indicates a lower susceptibility of disc-like particles to initial entrainment and lower transport …
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The Transient Flow Rheology and Instabilities of Polyethylene Melts
… the linear and non-linear behaviour (for lower shear rates) of these polyethylenes were determined from dynamic (oscillatory) experiments and stepstrain experiments performed using the Rheametrics (RDS), parallel-plate rheameter. Similar measurements using a capillary geometry with the MPR were …
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The Transient Flow Rheology and Instabilities of Polyethylene Melts
… the linear and non-linear behaviour (for lower shear rates) of these polyethylenes were determined from dynamic (oscillatory) experiments and stepstrain experiments performed using the Rheametrics (RDS), parallel-plate rheameter. Similar measurements using a capillary geometry with the MPR were …
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The Role of Geomorphic Features and Hydrologic Processes on Sediment Clusters in Gravel-Bed Rivers, Washington: A Field-Based Approach
… clusters were also tracked, and the velocity and critical shear stress required to entrain particles were calculated to determine the possible effects of clusters on the entrainment of sediment. An improved understanding of how clusters develop, evolve and affect the entrainment of sediment under …
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Characterizing soil erosion potential using electrical resistivity imaging
… grain size, percent clay, compaction, and shear strength. Many of these characteristics also influence soil in situ bulk electrical resistivity (ER) measurements. The objective of this study was to characterize soil erosion potential by correlating the in situ ER of soil with erodibility …
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Incipient Motion Under Shallow Flow Conditions
… and high Froude number on the dimensionless critical shear stress (Shields parameter). Spherical particles of four different densities and an 8mm diameter were used as movable test material. The relative depth ranged from 2 to 12 and the Froude number ranged from 0.36 to 1.29. The results …
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The Effects of Vegetation on Stream Bank Erosion
… was addressed by measuring the erodibility and critical shear stress of rooted bank soils in situ using a submerged jet test device. Additionally, several soil, vegetation, and stream chemistry factors that could potentially impact the fluvial entrainment of soils were measured. A total of 25 …
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Modeling of crack initiation, propagation and coalescence in rocks
… of a DDM code - FROCK - which currently uses a stress-based criterion proposed by Bobet (1997) to model crack initiation and propagation. Even though the predictions obtained with this criterion generally correspond to the experimental results, there are cases, in which the results obtained with …
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Probabilistic Characterization of Sediments Using a Combined Geotechnical and Geophysical Approach
… characterization of seabed surface sediments is critical for offshore engineering, naval applications, and understanding coastal sediment dynamics. Traditional geotechnical methods provide accurate point measurements but lack spatial continuity, while geophysical surveys offer broad coverage but …
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Experimental Study of Pathogenic Microorganism Resuspension from Mobile Bed Sediment in Irrigational Canals
… rate increases with the dimensionless bed shear stress. Based on these results, for the first time, two models were proposed, for correlating the concentration of PhiX174 with the dimensionless bed shear stress for different sediments. One model was proposed for sandy loam and loam, and the …
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The influence of a petrochemical discharge on the bioturbation and erosion potential of an intertidal estuarine mudflat (Humber estuary, UK)
… effect of this type of pollution. Using the CSM, critical shear stress values were found to be significantly lower from unpolluted sites, indicating higher erosion potential, than those from sites close to the discharge. As a result of this, the total mass of sediment eroded from unpolluted sites …
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The effects of variation in wave period and flow asymmetry in sediment dynamics
… been reported previously in terms of a (single) critical flow amplitude Reynolds number, Recrit=U?a/?. On the basis of observations undertaken using sinusoidal flows (Li, 1954) and during the present study, this is found to be the case for wave periods of T>3.5s, where mean Recrit=1.66×105. …
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Geotechnical Investigation and Characterization of Bivalve-Sediment Interactions
… sediments should be able to better withstand shearing, thereby increasing the critical shear stress required to erode material, compared to sediment without shell hash. Habitat suitability for bivalve colonies is also an important consideration to evaluate what surface enhancements may be …
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Influence of riparian vegetation on near-bank flow structure and rates of erosion on a large meandering river
… (LWD) on near-bank flow structure and boundary shear stress, and how the hydrodynamics varied during different hydrologic conditions. Data consist of time-averaged three-dimensional velocity measurements, which were obtained using a boat-mounted acoustic Doppler current profiler (ADCP) during …
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