The importance of drainage
Water has the capacity to infiltrate all structures, both of clay and of concrete. It impregnates both dams and their foundations, with insidious effects that can have serious consequences.
Today there are two ways of counteracting this action:
- Either by lowering the amount of water which passes through the structures and foundations, i.e. by reinforcing the sealing characteristics,
- Or by drainage, channelling the water to those parts of the structures where its effects will be least harmful.
The amount of water moving in earth-fill dams is more diffuse and greater. To deal with its effects, drainage systems are introduced, a permeable material such as sand or proper pipes.
In addition, the granulometric distribution of the material is designed to avoid the formation of deep seepage, or infiltrations of soil particles that gradually undermine the structure.
In concrete dams, the abutment will be reinforced to increasing its sealing characteristics, at the same time as incorporating conduit channels to drain infiltrating water.
Finally, when it comes to the foundations, water infiltration is cut off by injecting cement, and, if necessary, adding:
- drainage wells downstream of the dam (earth-fill structures),
- drainage holes to reduce the amount of water percolating under the foundations and to divert the remainder (concrete structures).