Types of Dams
‘Gravity’ dams´, as their name implies, resist the thrust of the retained water (resisting both sliding and overturning) by their own weight. Generally they will be constructed from mass (i.e. unreinforced) concrete. Roller compacted concrete may also be used.
‘Arched dams’ may be either curved in plan or in both plan and elevation. The design of the dam is such that the thrust of the retained water is resisted by the structural action of the concrete. The arch is an efficient shape for transferring the forces to the sides and floor of the valley. They are significantly thinner, and more economic on materials, than gravity dams but sections will still be large. Generally they will be constructed from reinforced concrete though prestressing may be used to improve the resistance to overturning.
‘Buttress dams’ may be flat or curved in section with the thrust of the water being resisted by a series of buttresses on the downstream face. The dam wall itself will be relatively thin as the force from the water has only to be transferred a short distance to the adjacent buttresses. As with arch dams, they will be constructed from reinforced concrete though prestressing may be used to enhance the resistance to overturning.