Nonburied Riprap Mattress Sizing for Single Piers in the Presence of Bedforms.

The present study focuses on riprap protection at single piers under live-bed conditions. The riprap mattress is displayed so that its top is leveled with the surrounding river bed, for ease in the construction process. Over 48 laboratory experiments have been carried out to understand the trend of the required riprap mattress width to protect single piers against edge and bedform undermining failures. The influence of bedform height on the required width is emphasized. A simple expression is given to calculate the required riprap mattress width; for low sediment transport rates the expressions given in the literature for clear-water conditions are recovered. [ABSTRACT FROM AUTHOR]