A dam constructed of concrete andor masonry, which relies on its weight and internal strength for stability. Constants for extending 6hour generaltype designstorm values west of. Guidelines for design of dams table of contents section title page preface to the january 1 1989 edition 1 introduction 2 2 definitions 3 3 hazard classification 5. Embankment dams this is one of the oldest types of dam. Classification of dam types with respect to sizeheight of the dam. Gravity dams are similar to embankment dams because they also use heavy weight and large size to exert enough force on the water, but gravity dams are made of concrete and considered more secure than embankment dams since concrete holds together well. These purposes may be irrigation, hydro power, watersupply, flood control, navigation, fishing and recreation. Gravity dams are dams which resist the horizontal thrust of the water entirely by their own weight. Archgravity dams are the types of dams that use combined engineering methods of arch dams and gravity dams.
Concrete gravity dams are typically used to block streams through narrow gorges. Types of dams, advantages, disadvantages and classification. A dam is a structure built across a stream, river or estuary to retain water. The earth dams are usually built in wide valleys having flat slopes at flanks abutments. An arch dam is a dam curved in plan and carries at major part of its water load horizontally to the abutments by arch action. Conventional concrete and roller compacted concrete are both addressed. Concrete dams gravity dams buttressdams arch dams gravity dams use their triangular shape and the sheer weight of their rock and concrete structure to hold back the water in the reservoir. There is no type of dam more permanent than one of the solid concrete, nor does any other type require less for maintenance. Dams can be constructed with one type of construction materials or a combination of several. Since gravity dams must rely on their own weight to hold back water, it is necessary that they are built on a solid foundation ofbedrock. A double curvature arch dam is an arch dam, which is curved vertically as well as horizontally. Dam awareness may 2018 introduction responsibility and.
Gravity dams gravity dams criteria for selection of dam site, construction material, forces acting on gravity dam, modes of failure, stability analysis, safety criteria, methods of design, stress analysis and stress contours, galleries, instrumentation, joints, keys, water seals, temperature control in concrete dams, foundation treatment. A buttress dam is a gravity structure that, in addition to its own weight. Each discussion is composed of two parts, the basic considerations and the criterion statement. For structures consisting of a section of concrete gravity dam within an embankment dam, the concrete section will be designed in accordance with this manual. Pdf design and analysis of concrete gravity dams researchgate. Gravity dams are constructed from masonry or concrete. Selection of the method of analysis should be governed by the type and. There are many different dam types and construction configurations. A gravity dam built up of boxes, crossed timbers, or gabions filled with earth. A dam is a hydraulic structure or assembly that is constructed across a river to form a reservoir on its upstream side for confining water for various purposes like hydropower, water supply, flood control, navigation, fishing and recreation, irrigation. It is the most important force, particularly for gravity dams. The foundation requirements are less stringent than those of gravity dams, and hence they can.
In these types of dams, since there is huge quantity of water in the dams, it exerts excessively high hydraulic pressures on bed of the dam. Amongst concrete dams, too, there are many varieties, the principal types of which described below. Concrete gravity dams are the most common form of concrete dam. Figure 2 shows types of dams by number in the united states, which are the dam types used in the nid database. The gravity profile is essentially triangular to ensure stability and to avoid overstressing of the dam or its foundation. Failure of gravity dams causes and its failure modes. The basic gravity profile is triangular in shape, but for practical purposes, is modified at. Pdf dams have been constructed for millennia, influencing the lives. Design and construction of concrete gravity dams nptel. Dams are critical infrastructure that provides construction essential water supply to communities for consumption, farming and industry, they often fulfill a role in terms of flood mitigation and are an essential component of any hydropower project. A gravity dam is a massive sized dam fabricated from concrete or stone masonry. A dam is a hydraulic structure of impervious material built across a river or stream to create a reservoir on its upstream side for storing water for various purposes.
A gravity dam is a huge sized dam mainly constructed from concrete or stone. As the entire load is transmitted on the small area of foundation, such dams are constructed where. Curved gravity dams designed for arch action and other types of concrete gravity dams are not covered in this manual. Seismic performance evaluation of concrete gravity dams. They are capable of holding a large amount of water behind it. Hollow dams are constructed of reinforced concrete. The mass weight of concrete and friction resist the reservoir water pressure. For the design purpose only unit length of the dam is considered. These types of dams are one kind of a temporary dam, although a well designed timber dam may exist for more than 20 years. Based on structure and design, dams can be classified as follows.
Pdf multiple step method of design of gravity dam and. Types of dams classification of reservoirs civildigital. This types of dams are curved in plan and carries at major part of its water load. Different types of dams have different interaction behaviours between the two parts. Concrete gravity dams usually run in a straight line across a broad valley and resist the horizontal thrust of the retained water entirely by their own weight. Gravity dam is constructed of concrete andor masonry andor laidup stone that relies upon its weight for stability. Stability of the dam largely depends upon this force. Ussd types of dams webpage arch dam a concrete or masonry dam, which is curved upstream so as to transmit the major part of the water load to the abutments. Gravity dams are relatively more strong and stable than earth dams. Other types of dams, including concrete arch, concrete buttress, and timber dams, are discussed briefly with an explanation of why their designs are not covered in this text. Types of dams site selection of dam civil engineering.
The basic considerations are intended to supply the. Below are the types of dams based on different criteria. This part of water load depends primarily upon the amount of curvature. Previous ferc gravity dam guidance dealt with nappe forces by. This type is usually selected on the basis of local. Table 1 describes some of the most common types of dams.
Types of dams on the basis of materials used in dam construction. Project practices show that for concrete gravity dams, the rock foundations have significant influence on the stress behaviours of the concrete dams up to onethird of the dam height from the. They are constructed to store water during the rainy season when there is a large flow in the river. This text is limited in scope to consideration of the more common types of dams constructed today. They are designed to hold back large volumes of water. Forces acting on a gravity dams with diagram geography. By using concrete, the weight of the dam is actually able to resist the horizontal thrust of water pushing against it. Gravity dams are a type of dam which is secured by making it of such a size and shape that it will resist overturning, sliding or crushing at the toe. Some gravity dams are gently curved in plan for aesthetic or other reasons, and. Because the canyon walls bear the bulk of the load, arch dams are thinly constructed, requiring less material than other types of dams constructed of reinforced concrete designed to transfer the water load both downward and to the buttresses hollow gravity dams with a solid upstream face and a buttressed downstream side.
Gravity dams a gravity dam is one which depends entirely on its own mass for stability figure 4. This types of dams needs to be regularly maintained. They represent 57% and 31%, respectively, of the total inventory. Although the weight of the earth dam also helps in resisting the forces, the structural behavior of an earth dam is entirely different from that of a gravity dam. These dams are classified based on construction material used, structure and design, functions, hydraulic design and size. Various types of dams are constructed based on their usage. Here is the most common dam types based on different parameters function. Gravity dams are constructed of vertical blocks of concrete with flexible seals in the joints between the blocks. Within parts i and ii, each criterion is discussed under its appropriate subject heading.
Dams constructed across such a valley then impound the. A dam constructed of concrete andor masonry on the outside but having a hollow interior relying on its weight for stability. Basically, gravity dams are solid concrete structures that maintain their stability against design loads from the. The axes may be slightly curved in the correct shape or upstream. Many concrete gravity dams have been in service for over 50 years, and over this period important advances in the methodologies for evaluation of natural phenomena hazards have caused the design. Classification of dams and types of dams on the basis of. And distribution selection of type of dams and reservoirs osamu arai. As compared to earth and rockfill dams gravity dams have the following advantages. There are numerous types of dams throughout the world. Of the total number of structures in service, earth fill and gravity dams constitute the two most common types of dams in japan. This cubic content when multiplied by the density, gives the total weight w of the. Failure of gravity dam occurs due to overturning, sliding, tension and compression. Pdf gravity dams are solid concrete structures that maintain their stability against.
This type of structure is durable, and requires very little. Dams are made from a variety of materials such as rock, steel and wood. These dams are heavy and massive walllike structures of concrete in which the whole weight acts vertically downwards. A dam and its rock foundation are the two integral parts of a system. A gravity dam is designed in such a way that it resists all external forces acting on the dam like water pressure, wind pressure, wave pressure, ice pressure, uplift pressure by its own selfweight. A concrete gravity dam is entirely dependent upon its own mass for stability. Cubic content of the cement concrete is determined for unit length of the dam. In india the trend for concrete dam is only of the gravity type and therefore the design other types of. Dams are constructed depending on the purpose for which they are used. Because so much concrete is needed to exert the force, gravity dams can be expensive.
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