A dam is a barrier that holds back and confines water in a lake or reservoir. Dams are typically built across rivers. Concrete or natural materials like earth and rock are typically used to construct dams, which in the case of the Hoover Dam and the Three Gorges are major engineering projects with a lengthy construction schedule.
An arch dam is shaped like an arch with the top pointing back into the water to create a very strong structural form that is resistant to the pressure of the water behind it. Arch dams are frequently utilized in narrow, steep-sided valleys because they are typically constructed of concrete and require adequate rock support for the foundations and sides.
Buttress dams have walls in the shape of triangles, or buttresses. These buttresses are spaced out at regular intervals on the downstream side to withstand water pressure from the upstream side. They should be built on sound stone and are commonly made of cement or workmanship. They can be very material-efficient due to the spacing between the buttresses.
Embankment dams have long been prevalent in the United Kingdom, typically on sites with wide valleys. They are typically constructed from locally quarried or excavated natural materials like compacted earth or rocks. In cross-segment, a dike dam is slope or bank molded, with a focal center produced using an impermeable material, for example, earth soils or cement, to forestall water section.
Dams made of gravity
Dams made of gravity hold their position. They are typically triangular in cross-section and are typically constructed from concrete, masonry, or both. They can be used in either wide or narrow valleys and must be constructed on solid rock.
Spillways are a part of a dam and are used to safely and controlledly move overflow water over, around, or through a dam. Among the various types of spillways are:
Spillway for spills:
Because it is curved to control the flow of water and is lower than other sections of the dam, this allows water to flow over and down its front face. most frequently used as a component of gravity or buttress dams.
Spillway in the side channel:
This diverts water into a side channel and then into the river downstream of the dam, which is located a short distance upstream of the dam. Their primary application is with embankment dams.
This is a round empty pinnacle that sits in the repository close to the dam. A funnel at the top of the shaft redirects the water downstream when the level of the water rises.
The construction of a dam calls for a wide range of specialists from a variety of fields and is frequently complicated. Most of the time, civil engineers are in charge of choosing the best dam for the location and creating technical drawings that show the construction process.
They’ll talk to engineering geologists and hydrologists about the site’s technical details and the requirements for how much water is needed. Contract work for the design of the necessary floodgates, valves, and pipework will be done by mechanical engineers.
Geotechnical designers will decide if the stone or soil underneath the proposed dam is sufficiently able to oblige the weight and for deciding conceivable porousness.
The following is a general outline of the typical dam construction sequence:
River diversion A dry area for the construction of the dam is created by diverting water from a river or stream.
Lower streams will be equipped for redirecting through passages or channels worked around the side of the dam region, unearthed utilizing explosives where fundamental.
A dry pit is formed on one side of the river, leaving the other side open for water to flow through because higher flows may be too difficult to divert through separate channels. The dry areas of the dam are constructed in order as sections. Openings are given in the dam to permit the stream to course through.
The foundation is built below ground level, with rock or weaker soils or soils being removed and, if necessary, replaced with stronger materials. Grout must be used to fill rock foundation cracks and fissures to prevent water leaks. The rock is drilled, and grout is pumped into the holes to fill the cracks and spread outward.
Construction of the dam
Concrete dams require a significant quantity of ready-mixed concrete, so a concrete batching plant is frequently constructed on-site. After that, trucks and cranes or a conveyor belt system are used to move the concrete to the dam. Pouring the concrete into a dam-specific formwork mold is the traditional method of installation. The dam is fabricated upwards 1-2 m at a time, and the substantial left to fix before the following segment is shaped on top.
Spreading a concrete mix and compacting it with rollers is another option. The dam is raised in 600-millimeter increments. Prior to using rollers to compact the concrete, thin layers of it are spread between the low concrete walls on the upstream and downstream faces.
From the bottom up, embankment dams are constructed in a series of thin layers. Tractors spread fill material in a far layer, typically 300 mm thick if utilizing earth, or up to 1 m thick for rock-fill. In order to maintain the same height as the rest of the dam, the core of the dam is also constructed in layers. Once the full height has been reached, the upstream face develops a protective layer. This safeguards against wave harm and frequently gives waterproofing.
If the reservoir was not filled during Dam construction (in the case of high-flow rivers), it can be filled after the dam has been built. It is necessary to conduct extensive testing on the valves and floodgates, as well as monitor the dam’s behavior.