Incipient Motion of Riverbank Sediments with Outflow Seepage
Publication: Journal of Hydraulic Engineering
Volume 135, Issue 3
Abstract
Based on a force analysis, an expression is derived to describe the critical Shields number for incipient motion of uniform cohesionless sediment particles on a riverbank slope in terms of flow parameters, outflow seepage, and physical and mechanical properties of sediments. Parametric studies were conducted to investigate quantitatively the effects of hydraulic gradient of seepage, slope angle, and flow direction on the critical Shields number. The results show that the critical Shields number decreases with an increase in the hydraulic gradient. Where bank collapse is concerned, the most dangerous direction of hydraulic gradient of outflow seepage is at an angle equal to the effective internal angle of friction of the sediment mass with respect to slope surface. At a certain value of hydraulic gradient, the critical Shields number decreases with increasing slope angle. Open flow becomes more erosive when the current direction changes from horizontally parallel with the riverbank line to turning downward.
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Acknowledgments
The writers would like to express their deep appreciation to Professor Qingyun Li, Director of the Geotechnical Engineering Department, Changjiang River Scientific Research Institute, Wuhan, China, for providing valuable suggestions and soil parameters for the example. This work was supported by the Foundation of State Key Lab of Hydroscience and Engineering, Tsinghua University, China (610103002) and National Basic Research Program of China (2007CB714102).
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Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 135 • Issue 3 • March 2009
Pages: 228 - 233
Copyright
© 2009 ASCE.
History
Received: Jul 8, 2007
Accepted: Aug 29, 2008
Published online: Mar 1, 2009
Published in print: Mar 2009
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