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Buttress dam

Types of Buttress Dams

Deck Slab Buttress Dam

Redridge Steel Dam is a flat deck slab buttress dam.

Buttress dams can be referred to as gravity dams or arch dams. It is a dam in which the concrete and material of the dam is designed to hold all the horizontal force and pressure of the water. The water pressure is distributed to the slab of the buttresses. Distributing this force will reduce the load on the wall making the dam have a longer life span. The deck slab buttress dam is similar to a gravity dam. This is a type of buttress dam that is supported by the corbels of the buttresses. The flat slab is supported by the buttress heads. Similar to a normal buttress dams this dam is reinforced by the buttresses. The buttress spacing depends on the height of the dam. The concrete slab is tilted horizontally about 40 to 55 degrees. This allows the deck of two buttresses to become one single part. There are multiple types of deck slab buttress dams including the fixed deck slab, a free deck slab and a cantilever. The fixed deck slab is a dam in which the deck and the buttresses are cast all in one single pour of the concrete. This means there is only one part of concrete rather than having a disconnect between the slab and buttresses. The free deck slab dam is also referred to as a simple deck slab buttress dam. The cantilever type buttress dam is one in which the deck slab is supported by a cantilever which is a long-extended beam.The upstream face is built like a brace and is on both ends of the dam.

Multiple Arch Buttress Dam

Cruachan Dam is a multiple arch buttress dam.

Gravity dams and buttress dams must be designed in a way where every section of the dam is balanced and durable. Buttress dams are also referred to as gravity dams or arch dams. The buttress dams are types of gravity dams. The multiple arch type of buttress dam has arch slabs that are on the upstream face of the buttress dams. Each of the the arches on the dam are supported by the buttresses. Multiple arch buttress dams are more enduring and flexible then other buttress dams, such as a deck slab buttress dam.The dam can either be constructed as a singular stiffened wall or a double hollow one.The centers between the arches are removed. The biggest disadvantage is that the buttresses depends on each other meaning that if one buttress develops problems the whole dam will lose its efficiency.  If one arch develops problems it will trickle down the sequence or arches. The depth of these arches often varies. This dam is best for larger heights preferably above 50 meters.The center angle of the arch must be 150 to 180 degrees to work. The area between the buttresses must be between 15 to 21 meters.

Massive Head Buttress Dam

Massive head buttress dams are a type of gravity dam. They are constructed with large amounts of concrete, and little reinforcement; this makes their construction relatively easy compared to other types of buttress dams. The sheer weight of the concrete makes massive head buttress dams very heavy, and very resistant to sliding. This type of buttress dam will not have a slab or arch at the upstream face like other buttress dams. Instead of having a slab at the upstream face the massive head buttress dam has buttress heads that are expanded and connected with other buttress heads. The larger buttress heads can be made into different shapes including round and diamond. These extensions of the buttresses is strengthened by using copper strips in the construction. Overall construction of massive head buttress dam is easier compared to other types of dams. The massive head buttress dam is resistant to sliding because of is weight. The massive head buttress dam is a heavy because of the large amounts of concrete used in construction. Massive head buttress dams are mainly designed to withstand static loads, and they can endure additional forces from natural occurrences such as silt build up, or a high water year. In general, massive head buttress dams do not hold up well against large floods or earthquakes due to concrete’s fragile properties. This fact, coupled with the lack of reinforcement in massive head buttress dams, means that they are not the best dams to have in earthquake prone areas.

Multiple Dome Buttress Dam

Multiple dome buttress dams are very similar to multiple arch buttress dams, but domes are built in place of arches. The main advantage of a multiple dome buttress dam is that domes can be spaced farther apart than arches can be placed. This helps save material, and reduces cost when designing the dam itself. Similarly to multiple arch buttress dams, multiple dome buttress dams are heavily reliant on every dome in the dam.If one of the domes fails, it is likely that the whole dam is compromised. Multiple dome or multiple arch buttress dams are most likely to fail at either end of the dam in the first dome or arch. This is because those two arches or domes take most of the force being exerted on the dam itself. When compared to multiple arch buttress dams, multiple dome buttress dams do not hold up as well in high stress environments. This is due to the fact that there is less reinforcement in the domes than in the arches. The multiple dome buttress dam is best used in places with little to no risk for earthquakes, and in waterways where flooding is minimal.

Columnar Buttress Dam

With the columnar buttress dam the columns support the deck slab of the dam. The columns are inclined to better support the flat deck of the dam. The flat deck slab are made to replace the buttresses. It is a altered deck slab buttress dam. It needs a very durable base. It requires skilled personnel to create the buttresses. This is why it is not used as much at the other types of buttress dams.