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TYPES OF DAM  Arch Dam An arch dam–reservoir system is shown in Fig. 8.7. The physical properties of the dam body and water are the same as those in the example of the gravity dam. The arch dam is of a height of 22 m and the near-field reservoir covers a region of the dam height. The dam body is discretized with 272 20-node hexahedron solid elements, the near-field reservoir with 1088 20-node hexahedron acoustic fluid elements, and the dam–reservoir interface with 136 eight-node interface elements. The farfield reservoir is modeled by 136 eight-node quadratic elements on the truncated boundary, which share the same nodes and are compatible with those of the near-field acoustic fluid elements. The total number of nodes of the whole model is 6652. To verify the results, a similar extended mesh covering the region of 7200 m is analyzed. Similar to the gravity dam example, the El Centro earthquake ground motion is imposed as the horizontal (Y direction) acceleration at the base of the arch dam. The time step is chosen as 0.02 s. The responses of the hydrodynamic pressure at the heel of the arch dam are plotted in Fig. 8.8. The solution of the direct coupled method agrees with the solution of the extended mesh and is longtime stable. However, as for the partitioned coupled method, numerical divergence is observed at early time-points in the analysis. Numerical instability of such coupling strategy is also reported by Soares et al. [12]. It can be expected as the partitioned coupled method is conditionally stable; that is, the integration time step is limited by stability limits. When the time step is greater than the stability limit, numerical

instability may occur, as in the results of the arch dam example. As the dam–reservoir system is quite complicated, it is difficult to determine the stability limits of different application cases. When the partitioned coupled method is applied, smaller time steps should be used.

 Hydropo

wer Dam A hydroelectric dam is one of the major components of a hydroelectric facility. A dam is a large, man-made structure built to contain some body of water. In addition to construction for the purpose of producing hydroelectric power, dams are created to control river flow and regulate flooding.[2] In some rivers, small scale dams known as weirs are built to control and measure water flow. Dams fall into the category of retaining structures, or structures that are built to create large standing bodies of water known as reservoirs. These reservoirs can be used for irrigation, electrical generation, or water supply. These structures are built on top of riverbeds and hold back water, raising the water level. Dikes can be built along with the dam to increase the dams effectiveness by preventing water from leaving the reservoir through secondary routes.[3] Dams can range from relatively small to extremely large structures. The highest dam in the United states is located near Oroville, California and stands at 230 meters tall and 1.6 kilometers across.[2] The largest dam in the world is the Jinping dam on the Yalong river in China, standing at 305 meters tall. In Canada, there are more than 10 000 dams, with 933

categorized as being large dams.[4] The tallest dam in Canada is the Mica dam, on the Columbia river, standing at 243 meters tall. Another notable Canadian dam is the W.A.C Bennett dam on the Peace river, notable for its large reservoir volume of 7.4 x 109 cubic meters and height of 190.5 meters. The construction of these dams is difficult and labour intensive. Before construction begins, water is diverted or prevented from moving through the construction site. After water is diverted, the foundation area is cleaned, excavated, and rock or sediments that will act as the foundation are repaired and deemed solid. This is done to ensure the rock or sediments won't shift or fail as a result of the load of the dam and reservoir. Supports known as rock bolts may be used to strengthen the foundation. Above the dam, rock bolts and netting may be used to prevent rocks from falling on the dam. Forms are then built along the edges of the dam, rebar is placed inside, and concrete is pumped in. This is done in sections, and the concrete is poured bit by bit in a block formation. Once enough of the dam is built, the reservoir is allowed to fill in a highly controlled manner. The dam is monitored during this process. Other structures that make the dam operational are then added.[5] Dams are just one component of a complete hydroelectric facility, but are one major, visible component in the system. The purpose of a hydroelectric dam is to provide a place to convert the potential and kinetic energy of water to electrical energy by using a turbine and generator. Dams act as the place where water is held back and released in a controlled manner through hydraulic turbines, enabling the mechanical energy of the water to be transformed to electrical energy.[6] Typical dams work to create a reservoir where water is stored at a given height. This height and the rate at which the water flows from the reservoir through the turbines determines how much electricity can be generated. This can be calculated by using the hydroelectric power equation. As the height of the dam increases, the amount of electricity generated increases as well. At the top of the dam is a gate that is used for blocking or allowing the release of water from the reservoir. This gate is opened or closed to meet electricity requirements. Between the top of the dam and

the turbines are a series of channels known as penstocks that guide the water down and control the slope of the falling water to ensure maximum efficiency of the dam. Finally, turbines can be contained in the dam structure itself, and this is where the energy conversion takes place. After the water passes through the turbines, it is released i n a tail race at the bottom of the dam back into the river.[6]

 Diversi

on Dam A diversion dam is a dam that diverts all or a portion of the flow of a river from its natural course. Diversion dams do not generally impound water in a reservoir; instead, the water is diverted into an artificial water course or canal, which may be used for irrigation or return to the river after passing through hydroelectric generators, flow into a different river or be itself dammed forming an onground or groundwater reservoir or a storm drain. An early diversion dam is the Ancient Egyptian Sadd el-Kafara Dam at Wadi AlGarawi, which was located about twenty five kilometres south of Cairo. Built around 2600 BC for flood control, the structure was 102 metres long at its base and eighty seven metres wide. It was destroyed by a flood while it was still under construction. Diversion dams are one of three classifications of dams which include: storage dams, detention dams, and diversion dams. Storage dams are used to store water for extended lengths of time. The stored water then can be used for irrigation, livestock, municipal water supply, recreation, and hydroelectric power generation. Detention dams are built to catch surface runoff to prevent floods and trap sediment by regulating the flow rate of the runoff into channels downstream. Diversion dams are used to raise the water level in order to redirect the water to the designated location. The diverted water can be used for supplying irrigation systems or reservoirs

Diversion dams are installed to raise the water level of a body of water to allow the water to be redirected. The redirected water can be used to supply irrigation systems, reservoirs, or hydroelectric power generation facilities. The water diverted by the diversion dam to the reservoirs can be used for i ndustrial applications or for municipal water supply Like the name says, a diversion dam is used to divert water. They provide pressure to push water into ditches, canals, or other areas used for conveyance. Diversion dams are typically lower in height and have a small water storage area in it’s upstream.

 Storage

Dam These dams are not mean to divert or keep water out, but to keep water in. Storage dams are constructed to store water during the rainy seasons, supply water to the local wildlife, and store water for hydroelectric power generation, and irrigation. Storage dams are the most common types of dams. Storage dams are constructed to store water during the rainy seasons, supply water to the local wildlife, and store water for hydroelectric power generation, and irrigation. Storage dams are the most common types of dams.

 Gravity

Dam

An '''arch-gravity dam '''or arched dam is a dam with the characteristics of both an arch dam and a gravity dam. It is a dam that curves upstream in a narrowing curve that directs most of the water against the canyon rock walls, providing the force to compress the dam. It combines the strengths of two common dam forms and is considered a compromise between the two. They are made of conventional concrete, Roller Compacted Concrete (RCC), or masonry. Archgravity dams are not reinforced except at the spillway. A typical example of the conventional concrete dam is the Hoover Dam. Changuinola Dam is an example of the RCC arch-gravity dam. A gravity dam requires a large volume of internal fill. An arch-gravity dam can be thinner than the pure gravity dam and requires less internal fill A gravity dam is a structure designed to withstand loads by its own weight and by its resistance to sliding and overturning on its foundation. Newer dams of this type are typically composed of unreinforced concrete monoliths with seals at the joints. Foremost among the world's gravity dams is the 285-meter-high (935-foot-high) Grande Dixence in Switzerland, completed in 1961. In past centuries, many gravity dams were constructed of stone masonry. New masonry dams, of both gravity and arch designs, are being built in India and China and in other lands where the cost of labor is low. Also of historic interest is the filled crib, the stability of which depends upon the weight of earth or rockfill enclosed in cells formed by a framework of timbers or concrete beams. Such dams, common a hundred years ago, were usually faced with timber planking. A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it.

 Concrete dam Concrete dams are gravity dams usually built in large blocks divided by joints to make the construction more convenient and reduce thermal stress. The joints are grouted after the dam is cooled. Transverse joints are perpendicular to the dam axis. A concrete dam is a major construction project that needs a massive amount of concrete, resulting in the use of a large amount of cement. Cement production is causing CO2 emissions that are detrimental to the environment and is also a high-cost procedure. Concrete dams are very large structures; generally they are divided into blocks by joints to make the construction more convenient and reduce the thermal stress. The joints are grouted after the dam is cooled. Transverse joints are perpendicular to dam axis. The spacing between them is about 15–20 m, which might be different in a same dam as hydraulic arrangement required. In the RCC dams, there is generally no longitudinal joint, but the transverse joints are still set by a vibrating grooving machine. Longitudinal joints are parallel to dam axis, the spacing between them is about 15– 40 m. With the development of dam construction technology, nowadays, there is generally no longitudinal joint in both gravity and arch dams. The thickness of the concrete lift depends on three factors: (i) the effectiveness of superficial heat dissipation, (ii) the rising speed of the dam, and (iii) the convenience of construction.