Rock scour in Australia: Some latest Queensland experiences

Bollaert, E.; Lesleighter, EJ; McComber, S.; Bozorgmehr, P.; Fahey, Liam; Scriven, D.

doi:10.1201/9781315375045-69

Cited by 2 publications

(1 citation statement)

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“…At Paradise dam, no damage to the stepped chute itself was reported after a succession of major flood events that took place between 2010 and 2013 [6]. In turn, damages were recorded at the basin apron, with pronounced downstream scouring [8,9].…”

Section: Introductionmentioning

confidence: 99%

Extreme Pressures and Risk of Cavitation in Steeply Sloping Stepped Spillways of Large Dams

Matos

Novakoski

Ferla

et al. 2022

Water

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Stepped spillways have been increasingly used to handle flood releases from large dams associated with hydropower plants, and it is important to evaluate the fluctuating pressure field on the steps. Hydraulic model investigations were conducted on three 53° (1V:0.75H) sloping and relatively large-stepped chutes to characterize the mean, fluctuating, and extreme pressures acting on the most critical regions of the step faces, near their outer edges. The pressure development along the chutes is presented, generally indicating an increase of the modulus of pressure coefficients up to the vicinity of the point of inception of air entrainment, and a decrease further downstream. The extreme pressure coefficients along the spillway are fitted by an empirical formula, and the critical conditions potentially leading to cavitation on prototypes are calculated. The correlation between the cavitation index and the friction factor is also applied for predicting the onset of cavitation on prototypes, and the results are compared with the pressure data-based method. Generally, the results obtained from those methods yield typical values for the cavitation index in the vicinity of the point of inception, varying approximately from 0.8 to 0.6, respectively. In light of these results, maximum unit discharges of about 15–20 m2/s are considered advisable on 53° sloping large-stepped spillways without artificial aeration, for step heights ranging from 0.6 to 1.2 m. For much higher unit discharges, a considerable reach of the spillway may potentially be prone to the risk of cavitation damage.

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Section: Introductionmentioning

confidence: 99%