Laboratory and theoretical evaluation of impact of packing density, particle shape, and uniformity coefficient on erodibility of coarse‐grained soil particles. Issue 7 (6th February 2020)

• Record Type: Journal Article
• Authors: Choo, Hyunwook; Zhao, Qian; Burns, Susan E.; Sturm, Terry W.; Hong, Seung Ho
• Is Part Of: Earth surface processes and landforms. Volume 45:Issue 7(2020)
• Page Start: 1499
• Page End: 1509
• Publication Date: 2020-02-06
• Subjects: critical shear stress -- erodibility -- coarse grains -- median grain size -- packing density -- particle shape -- uniformity coefficient; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.4825
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: Sedimentation – including erosion, transport, and deposition of coarse‐grained particles – is a primary and growing environmental, engineering, and agricultural issue around the world. Soil erosion occurs when the hydrodynamic force induced by flowing water exceeds the geotechnical resistance of soils, as measured by critical shear stress for initiation of soil‐particle motion. Even though various quantitative methods have been suggested with respect to different types of soil, the most widely accepted formula to estimate critical shear stress for coarse‐grained soil is a direct function of the median grain size of the soil particles; however, the erosion resistance of soils also varies with other geotechnical properties, such as packing density, particle shape, and uniformity coefficient. Thus, in this study, a combined rolling–lift model for particle detachment was derived based on theoretical analysis. A series of experimental flume tests were conducted with specimens prepared with standard soil types, as well as laboratory‐prepared mixtures of coarse‐grained soil to validate the theoretical model and determine the effect of other geotechnical properties on the erosion characteristics of coarse grains, coupled with the effect of median particle size. The results indicated that the median grain size is the primary variable determining the resistance of coarse grains, but the critical shear stress also varies with the packing density of the soil matrix. In addition, angular particles show more erosion resistance than rounded particles, and the erosion potential of a soil decreased when the grain is well graded (higher value of uniformity coefficient). Additionally, regression analysis was performed to quantify the effect of each parameter on the critical shear stress of coarse grains. © 2020 John Wiley & Sons, Ltd. Abstract : The effect of geometric parameters on critical shear stress for soil particles was investigated by theoretical analysis and laboratory experiment. A new formula for critical shear stress estimation was suggested and the formula, together with the Shields diagram, can be used to calculate critical shear stress more accurately.