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Title:	Cohesive sediment erosion
Authors:	Lee, Say-Chong. Mehta, A. J. (Ashish Jayant), 1944-
Keywords:	Marine sediments--Testing Sediment transport--Measurement--Instruments Sedimentation and deposition--Measurement Soil consolidation test
Publisher:	U.S. Army Engineer Waterways Experiment Station.
Series/Report no.:	Contract Report (Dredging Research Program (U.S.)) ; no. Contract Report DRP-94-6
Abstract:	This report consists of three chapters: Chapters 1 and 2 deal with erosion test devices and field instrument assemblies, while Chapter 3 is an analysis of published erosion rate-bed shear strength data in an attempt to establish a functional link between the characteristic erosion rate constant (defined as the slope of the erosion rate-bed shear stress plot). A wide range of erosion test devices has been used both in the laboratory and in the field in the effort to further elucidate the phenomena of cohesive sediment erosion. They differ in configuration and flow geometry, size, mechanisms of generating flow, operation protocol, and measurement methodology. These devices are further complemented by various custom-designed field instrument assemblies, which provide valuable prototype data for model calibration and validation. The report reviews six categories of laboratory erosion test devices and eight categories of field devices/measuring assemblies. For each category, a representative device from the literature is described with a view to illustrating its salient features and typical test results. Similarly, the field instrument assemblies are individually described, including a brief discussion on typical field results. The description is confined to a documentation of the suite of equipment with incidental comments on their merits without an effort to compare them on a relative basis. In Chapters 1 and 2, 152 pairs of measured erosion rate constant-bed shear strength values have been gleaned from the literature for analysis. The data are limited to those that exhibit a linear relationship linking the rate of erosion to the bed shear strength. A family of curves of the functional form is apparent from the data spread. Further examination of the trend of several important erosion resistance characterizing factors reveals that the succession of curves behaves consistently with respect to the variation in the state of sediment bed (undisturbed or remolded) and the total salt concentration in the pore fluid. Based on these observations, a nomograph has been suggested for estimating the erosion rate constant, given the bed shear strength, subject to the caveat that the nomograph be used only as a last resort to provide general guidance, and is not intended to supplant erosion experiments, which should always remain the first choice. It may be noted that the nomograph is applicable only for placed beds/undisturbed beds/remolded beds which have a uniform shear strength with depth.
Description:	Contract Report
Gov't Doc #:	Contract Report DRP-94-6
Rights:	Approved for Public Release; Distribution is Unlimited
URI:	https://hdl.handle.net/11681/33124
Size:	88 pages / 5.253 Mb
Types of Materials:	PDF/A
Appears in Collections:	Contract Report