Simple and reliable operation.
Made of concrete or steel, fusegates are installed side-by-side on the dam’s spillway crest. Thanks to a sophisticated lateral sealing joint system, the fusegates act as a waterproof wall in all conceivable configurations: straight-crested, single-curvature, double-curvature ungated sill on an arch dam, etc.
The interaction of the downstream toe abutments with the ballast in the fusegate guarantees the stability of the unit against the water pressure. Precise adjustment of the drain hole enables the base chamber to be drained of any accidental leakage while ensuring a rise in pressure once the inlet well begins to fill. Set at a predetermined level, the filling of the inlet well is set to coincide with the tipping level of the fusegate.
The reservoir level is then increased to reach the top of the crest of the fusegate modules (Fig. 1).
In flood conditions, when the reservoir is full, the water flows over the crest of the fusegate, which acts like an ungated spillway (Fig. 2).
In exceptional flood conditions, the water level in the reservoir reaches tipping point: water pours into the inlet well to flood the base chamber (Fig. 3).
Once the drain holes are saturated, pressure builds up beneath the module. This generates a discontinuity in the force ratio which leads to destabilization of the fusegate, causing it to overturn in the downstream direction (Fig. 4).
As the water level continues to rise, the fusegate modules tip sequentially, one after the other. Their tipping threshold is set precisely by the height adjustment of their inlet well, to ensure that the units overturn progressively in order to compensate for the effect of exceptional flood levels.
A highly-developed system
Hydroplus® has developed options designed to optimize the cost and operation of the fusegate and maximize its reliability:
- the shape of the fusegate: straight-crested fusegate, labyrinth-crested fusegate, semi-labyrinth-crested fusegate, piano key weir fusegate;
- deflectors for slaving one fusegate to another fusegate;
- remote inlet wells in a water intake tower;
- protected inlet wells;
- watertight systems