Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Zhang, Gangfu; Chanson, Hubert

doi:10.1061/(asce)hy.1943-7900.0001120

Cited by 18 publications

(7 citation statements)

References 9 publications

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“…On the other hand, tests performed on non-standard configurations, such as gabions, pooled steps and non-uniform steps, have reported changes in flow patterns, air entrainment and energy dissipation from a standard design (e.g. Stephenson 1988, Gonzalez and Chanson 2008, Felder and Chanson 2014, Wuthrich and Chanson 2014, Zhang and Chanson 2016a. While these investigations highlighted the importance of bottom geometry in determining the characteristics of stepped chute flows, their conclusions had not always been consistent.…”

Section: Introductionmentioning

confidence: 99%

Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Zhang

Chanson

2018

J. Hydraul. Eng.

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The effects of step edge and cavity shapes on skimming flow properties were investigated in a large-size 45° stepped chute model configured with uniform triangular steps, partially blocked cavities, and chamfers. The focus of this experimental study was the air water flow regime and the energy dissipation performances. Visually, the partial cavity blockage and chamfers were respectively associated with an increase and a decrease in flow stability, while causing no substantial change in the general flow regimes. Comparisons of characteristic air-water properties indicated better aeration performance for the sharp edges than for the chamfers. A substantial reduction in friction factor was observed with the chamfers, while partial cavity blockages appeared to slightly improve flow resistance. A strongly negative correlation between total air entrainment and flow resistance was identified, which was more observable for the sharp edges. A comparative study revealed that sparsely spaced sharp edges at slopes between 30° and 45° might be optimal in terms of aeration and energy dissipation performances.

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Section: Introductionmentioning

confidence: 99%

Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Zhang

Chanson

2018

J. Hydraul. Eng.

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“…The second type is for supercritical flow with the partial hydraulic jump, and the third type is for supercritical flow without a hydraulic jump. The limits of the nappe flow regime on the gabion weir can be calculated in terms of the critical depth of flow (yc) and step height (hs) using the empirical onset of the transition flow regime on the gabion stepped weirs can be obtained in terms of the critical depth of flow and step height using the empirical formulae of both of Wuthrich and and Zhang and Chanson (2015) [16,17] as follows:…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effect of Downstream Slope and Rockfill Materials on Flow Regimes over Gabion Stepped Weirs

Alabas¹,

Jahad²,

Al-Ameri³

et al. 2023

Pol. J. Environ. Stud.

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It is important to determine the limits of flow regimes in the design of stepped weirs because of the hydraulic performance of each regime. The present study investigates the effect of downstream slope and rock fill materials on flow regimes in gabion stepped weirs. Nine physical models of gabion weirs were used in the experiments. The models' downstream slopes ranged from 1:05 to 1:4 V:H. In addition, two types of rockfill materials: crushed stone of 0.42 porosity and rounded gravel of 0.38 porosity were used to study the effect of rockfill materials on flow regimes. The nominal size of the crushed stone was (37.5 mm -13.2 mm) D50 = 23 mm and the nominal size of the rounded gravel was (26.5 mm -13.2 mm) D50 = 16 mm. Each model has been tested with ten runs for discharge per unit width ranging (from 0.006 to 0.105 m 3 /sec. m) to cover all flow conditions and flow regimes. The onset of each flow regime for all physical models has been observed. The experimental data of the gabion stepped weirs have been used to develop equations to estimate the onset of each flow regime. The coefficient of correlation (R) of the developed equations ranged between 0.95 to 0.97. The results indicated on the steeper downstream slope models (1:0.5, 1:0.83), there is interference between the nappe and transition flow regimes. The nappe flow regime has not appeared on all steps at the same

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“…Several experiments performed for modified bottom geometries have demonstrated modifications of energy dissipation and aeration performance to different extents (e.g. Stephenson (1988) on varying step sizes, Gonzalez and Chanson (2008) on steps with vanes, Felder and Chanson (2014b) on pooled steps, Wuthrich and Chanson (2015) and Zhang and Chanson (2016a) on gabion steps). It is of interest to investigate how modified bottom geometries would affect the air-water flow properties in a stepped chute.…”

Section: Introductionmentioning

confidence: 99%

Air-water flow properties in stepped chutes with modified step and cavity geometries

Zhang

Chanson

2018

International Journal of Multiphase Flow

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Skimming air-water flow properties were investigated in a stepped chute configured with triangular steps, chamfered steps, and partially blocked step cavities. The turbulent interactions between air and water were examined using a synchronised system consisting of a dual-tip phase-detection probe and a pressure transducer mounted side-by-side. In comparison to uniform triangular steps, the chamfered steps were found to cause a reduction in air entrainment and an increase in mean velocity gradient next to the pseudo-bottom. Partial cavity blockages appeared to have little effect on air entrainment, but were linked to an increased presence of large-scale structures in the overflow, which likely resulted from a reduction in mutual sheltering between adjacent step elements. The results indicated that modifications of step and cavity geometries might have significant implications on stepped chute design.

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Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Cited by 18 publications

References 9 publications

Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Effects of Step and Cavity Shapes on Aeration and Energy Dissipation Performances of Stepped Chutes

Investigation of the Effect of Downstream Slope and Rockfill Materials on Flow Regimes over Gabion Stepped Weirs

Air-water flow properties in stepped chutes with modified step and cavity geometries

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