Gabion

Résumé

thumb|200px|Gabions en grillage métallique inoxydable utilisés en murs de soutènement. Sur des sols limoneux, faute de fixation par la végétation, l'eau peut emporter de la terre au travers du gabion. Un gabion (de l'italien gabbione signifiant « grosse cage ») est en génie civil un casier, le plus souvent constitué de nos jours de solides fils de fer tressés, et rempli de pierres généralement non-gélives (qui ne se fendent pas sous l’action du gel). Ils sont utilisés dans les travaux publics et le bâtiment pour construire des murs de soutènement, des berges artificielles non étanches ou décorer une façade nue ou des aménagements urbains. D'un coût modique si l'on dispose de pierres solides sur place, et d'une bonne tenue, ils sont relativement faciles à mettre en œuvre et aisément modulables. Les gabions peuvent être constitués par tissage de fils métalliques (mailles hexagonales double torsion) ou par soudage de fils (électrosoudage) avec des mailles carrées ou rectangulaires. En

Source officielle

https://fr.wikipedia.org/wiki/Gabion

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Hydraulics, Air Entrainment, and Energy Dissipation on a Gabion Stepped Weir

Davide Wüthrich

In the last decades the design of stepped spillways regained some interest because of their suitability with new construction methods including gabions. The hydraulic performances of gabion stepped weirs were investigated experimentally in terms of the flow patterns, air-water flow properties, and energy dissipation. A laboratory study was conducted in a 26.6 degrees slope (1V: 2H) and 0.10-m step height facility, with both smooth impervious and gabion steps. The visual observations highlighted the seepage flow through the gabions, inducing a modification of the cavity flow especially in the skimming flow regime. In skimming flows, higher velocities were measured at the downstream end of the gabion stepped chute, associated with smaller energy dissipation rates and lower friction factors, compared to the smooth impervious stepped chute data. (C) 2014 American Society of Civil Engineers.

American Society of Civil Engineers2014

Chargement

The stepped spillway design has been used for more than 3,300 years. A simple structure is the gabion stepped weir. A laboratory study was performed herein in a large size facility. Three gabion stepped weirs were tested with and without capping, as well as a flat impervious stepped configuration. For each configuration, detailed air–water flow measurements were conducted systematically for a range of discharges. The observations highlighted the seepage flow through the gabions and the interactions between seepage and overflow. The air–water flow properties showed that the air concentration, bubble count rate and specific interface data presented lower quantitative values in the gabion stepped weir, compared to those on the impervious stepped chute, while higher velocities weremeasured at the downstream end of the gabion stepped chute. The re-oxygenation rate was deduced from the integration of the mass transfer equation using air–water interfacial area and velocity measurements. The aeration performances of the gabion stepped weir were lesser than on the flat impervious stepped chute, but for the lowest discharge. For the two configurations with step capping, the resulting flow properties were close to those on the impervious stepped configuration.

Springer Verlag2015

Chargement

Air Entrainment and Energy Dissipation on Gabion Stepped Weirs

Davide Wüthrich

In the last three decades the design of stepped spillways regained some interest because of their suitability with new construction methods including gabion placement. In this study, the hydraulic performances of gabion stepped weirs were investigated experimentally in terms of the air-water flow properties and energy dissipation rate. A physical study was performed in a relatively large size facility with a 26.6° slope (1V:2H) and 0.10 m step height. For both gabion and impervious stepped weirs, a detailed comparison of the air-water flow properties was performed. The visual observations highlighted the seepage flow through the gabions, including a modification of the cavity flow dynamics, especially in the skimming flow regime. In skimming flows, higher velocities were measured at the downstream end of the gabion stepped chute, associated with lesser energy dissipation rates.

2014

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