Incipient Motion of Riprap on Steep Slopes
Publication: Journal of Hydraulic Engineering
Volume 141, Issue 9
Abstract
Liu’s theory of 1957 to estimate the point of incipient motion, derived assuming a flat bed slope and uniform flow, states that for large particles the movability number (defined as the ratio of the shear velocity to the settling velocity), is constant. Data collected from 12 undistorted and unscaled laboratory tests was used to investigate the applicability of the theory on steep riprap slopes. The tests indicate that the dimensionless movability number (MN) is constant for large particle Reynold numbers. For design purposes, the recommended movability number which emerged from this study is 0.18, provided that the steep bed slope is taken into account, the energy slope is considered in MN, and that the theoretical settling velocity is calculated using an accurate drag coefficient and the sieve size of the riprap.
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© 2015 American Society of Civil Engineers.
History
Received: Nov 22, 2013
Accepted: Feb 4, 2015
Published online: May 12, 2015
Published in print: Sep 1, 2015
Discussion open until: Oct 12, 2015
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