Development of riprap design criteria by riprap testing in flumes: Phase II, Followup investigations

Flume studies were conducted in which riprap embankments were subjected to overtopping flows. Embankments slopes of 1, 2, 8, 10, and 20% were protected with riprap containing median stone sizes of 1, 2, 4, 5, and/or 6 in. Riprap layer thickness ranged from 1.5 D/sub 50/ to 4 D/sub 50/. Riprap design criteria for overtopping flows were developed in terms of unit discharge at failure, interstitial velocities and discharges through the riprap layer thickness and gradation on riprap stability, and potential impacts of integrating soil into the riprap layer for riprap stabilization. A riprap design procedure is presented for overtopping flow conditions.