A detailed sketch of a gravity dam is shown in fig. A concrete gravity dam is a massive concrete structure, roughly triangular in shape, and designed so that its weight ensures structural stability against the hydrostatic pressure of the impounded water and other forces that may act on the dam. Failure of gravity dam occurs due to overturning, sliding, tension and compression. 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. Failure of gravity dams causes and its failure modes.
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. The dam will have a nonoverflow section on the western side and a channel spillway section on the eastern side ministry of water recourses and electric power of peoples republic of china, 1979. The water presses laterally downstream on the dam, tending to overturn the dam by rotating about its toe a point at the bottom downstream side of the dam. A gravity dam is a dam constructed from concrete or stone masonry and designed to hold back water by primarily using the weight of the material alone to resist the horizontal pressure of water pushing against it. In a gravity dam, the force that holds the dam in place against the push from the water is earths gravity pulling down on the mass of the dam.
All the predominant forces that act on the dam have been shown in the figure itself. The axes may be slightly curved in the correct shape or upstream. 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. Fem modeling of concrete gravity dams 3 figure 3 an aerial photo of the baozhusi dam and hydropower station. This type of a structure is most durable and solid, and requires very little maintenance. A gravity dam is mostly straight in plan and is known as straight gravity dam. Work out the magnitude and dimensions of all the vertical forces acting on the dam and their algebraic sum, i. A curved gravity dam resists the external forces by its weight and not by arch action. 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. The stability of a dam can be analysed in the following steps. The most ancient gravity dam on record was built in egypt more than 400 years b.
Gravity of the dam material then, dam will be a low gravity dam. Forces acting on a gravity dams with diagram geography. Gravity dams may be classified by plan as straight gravity dams and curved gravity. Pdf design of gravity dam table of contents theogene. A gravity dam has been defined as a structure which is designed in such a way that its own weight resists the external forces. Gravity dams are designed so that each section of the dam is stable and independent of any other dam section.