Structural Elements of DamsArticles > Structural Elements of Dams
Structural Elements of Dams:
Dams are construction used to resist or stop the flowing water of a stream or river. A barrier/wall of a wide span is built before the way of flowing water, which allows a controlled quantity of water, and the rest of the water is stored or reserved for the future time of water deficit. Detailed article about the dams and their types have already been uploaded to this website, however, the structural elements of dams are still needed to be discussed in detail. As far as the structural parts of the dams are concerned, they are almost the same in all types of the dam, different designs of the dams may vary the designs of the elements of the dam.
Structural Elements of Dams:
A dam structure may be divided into three parts:
1. Water Retaining Structure
2. Water Releasing Structure
3. Water Conveying Structure
(1). Water Retaining Structure:
The water retaining structure is the walled structure of the dam, which resists the water and allows a controlled quantity to flow downstream. The side of the wall or dump which faces the down-stream is called the face of the dam. The plane top surface of the dam is called the crest of the dam. The crest is a roadway across the dam. The crest of the dam is constructed on the top of the spillway. This includes the total length of the dame. It is the overflow section of the dam. The water-retaining portion of the dam has the following elements.
- Abutments: The part of the valley sides of the dams, constructed with concrete material or masonry work. The function of the abutments is to provide support to the wall of the dam.
- The base of the Dam: The base is the total width of the basement of the dam, which descends with vertical ascend of the dam.
- Crest: Crest the uppermost plane surface of the dam. It is the overflow part of the dam.
- Cutoff: The cut-off of the dame is an impervious material, which prevents the seepage of water through the base section of the dam.
- Cut-off Wall: The wall of impervious material like wood panels, concrete, or steel is constructed in the core of the dame. The purpose of this wall is to prevent seepage. Keep in view that seepage harms the solidarity of the dam.
- The face of the Dame: The side of the dam which is faced by the downstream.
- Upstream: Upstream of a dam is the level of water reservoir held back by the dam. The water of Upstream flows through the conduit toward the downstream.
- Parapet Walls: The parapet walls of the dams are constructed on the crest of the dam. The function of the parapet wall is to give protection to the tourists.
- The heel of the dam: The junction of the upstream face with the foundation of the dam is called the heel of the dam.
- Toe of the dam: The junction of downstream of the dam with the ground is called the toe of the dam.
(2). Water Releasing Structure of the Dam:
The water releasing structure is the part of the dam which allows water to release downstream. It is, technically called Spillways of the dam. The mechanism of the spillway is to allow the controlled water quantity. A spillway has the following elements.
- Crest Gate/ Spillway Gate: These gates are installed on the crest of the spillway. The duty of these gates is to allow a controlled quantity of the reservoir water.
- Flap Gate: They are flow control gates, which are hinged from their top.
- Outlet Gate: It controls the outlet flow of water from the reservoir.
- Radial Gate: A gate with radial arms and curved upstream plates.
- Slide Gate: This type of gate can be opened and closed by sliding it.
Types of Spillways:
There are two types of spillways:
- Auxiliary Spillways: Auxiliary spillways are constructed along or above the crest of the main spillway. They are designed for emergency release of water, to prevent the damage of the dam. The rupture or damage of a dam can cause a deadly flood.
- Ogee Spillways: It is an overflow spillway, which is constructed in cross-section the crest, downstream slope, and bucket in an “S” shape or ogee form of a curve. The shape is designed to prevent the high-velocity water to damage the downstream area near the bottom of the dam.
(3). Water Conveying Structure of the Dam:
Conduits are the parts of the outer work of the dams. The function of the conduits is to convey the water from reservoirs through, around, or under an embankment dam. Many dams have conduits that serve as a spillway.
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