Author(s): Taeksang Kim; Mamoon Kareem; Ries Plescher; Mohammed Alshamlan; Adna Mohamed Saed; Daniel Che; Kevin White And Jeremy Bricker

Linked Author(s):

Keywords: Culvert scour; Riprap design; Sand bed saturation; Outlet flow regime; Hydraulic experiment; Froude similarity

Abstract: Scour at culvert outlets threatens infrastructure stability, necessitating effective riprap design for erosion control. This study investigates the influence of sand bed saturation and outlet flow regime on the required riprap length for culvert scour protection. Laboratory experiments were conducted under controlled conditions and scaled to prototype values using Froude similarity. The results reveal that saturated sand beds require significantly longer riprap protection than unsaturated beds, particularly at higher flow velocities. Additionally, the distinction between subcritical and supercritical outlet flow regimes is crucial, as riprap length requirements follow distinct trends. A key finding is that using outlet flowrate as the predictive variable yields a more consistent linear relationship across different pipe sizes compared to outlet velocity, especially in supercritical conditions where velocity alone fails to capture riprap stability trends. These insights emphasize the necessity of integrating both sand saturation and outlet flow regime into riprap design, improving culvert stability while optimizing material use.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1708-cd

Year: 2025