Buttress Dam

a dam in which the water pressure of the headrace, which is absorbed by the pressure floor (in the form of plates or vaults), is transmitted to buttresses and the foundation. Buttress dams are constructed primarily from concrete and reinforced concrete. There are two types of buttresses: solid or open massive (concrete and rubble concrete) and thin (concrete and reinforced concrete). To ensure the stability of thin but-tresses, stiffening girders (braces), which prevent buckling, are placed between them.

Buttress dams are divided into the following categories according to the type of pressure floor: massive-buttress, made of concrete with massive cantilever caps adjoining one another and forming a pressure floor (Figure 1, a); the slab-and-buttress type, with reinforced-concrete slabs (Figure 1, b); the multiple-arch type (arched or vaulted concrete and reinforced-concrete floors; Figure 1, c); and with double-curvature floors, particularly the dome (multiple-dome) type.

Figure 1. Buttress dams: (a) massive-buttress type, (b) slab-and-buttress type, (c) multiple-arch type

Both fixed and spillway buttress dams are built. In comparison with massive gravity dams, buttress dams (especially the multiple-arch type) produce savings of 40 percent and more in concrete and costs, depending on the design and local conditions. The height of buttress dams sometimes exceeds 100 m.