Aug 28, 2015 gravity dams are well suited for blocking rivers in wide valleys or narrow gorge ways. Gravity dams are solid concrete structures that maintain their stability against design loads from the geometric shape and the mass and strength of the concrete. Pdf structural analysis of a gravity dam using finite. Response spectrum analysis of concrete gravity dams including. A free water surface may be subjected to atmospheric. Dec 14, 2016 chapter 6 concrete dam engineering with examples 1. The weight of gravity dam will cause a moment opposite to the overturning moment and the friction on the base will prevent the dam from sliding. Failure of gravity dams causes and its failure modes. Forces water pushes against the gravity dam, but the heavy weight of the dam pushes down into the ground and prevents the structure from falling over. A detailed sketch of a gravity dam is shown in fig.
Gravity dams are constructed from masonry or concrete. In practice, a free water surface is one that is not in contact with an overlying vessel cover. The gravity dam has sufficient weight so as to withstand the forces and the overturning moment caused by the water impounded in the reservoir behind it. Stability analysis of concrete gravity dam an overview.
Forces acting on a dam structure and calculations the constructor. Gravity dam casei reservoir full case when reservoir is full, the major forces acting are weight of the dam, external water pressure, uplift. Jan 28, 2014 gravity dams a gravity dam has been defined as a structure which is designed in such a way that its own weight resist the external forces. This manual applies to all hqusace elements, major subordinate commands. Hirakud dam across river mahanadi in eastern india is a composite structure of earth, concrete and masonry. The observation of the behavior of concrete gravity dams that are exposed to seismic loads is the main factor for the safety evaluation of the dams.
Computation of forces these forces fall into two categories as. Pdf structural analysis of a gravity dam using finite elements. It is calculated by the frictional force and horizontal forces on the dam, it should not be less. The model in thesis is the structure of hirakud gravity dam.
Pdf hydrodynamic forces on gravity dams due to earthquakes depend in a complicated way on the deformation of the dam and the reservoir. The canyon walls push back, counteracting these forces. By researching the size and direction of all the forces acting on a dam, engineers design a structure that is able to resist all these forces. Elementary profile of a dam subjected only to external water pressure on upstream side, will be right angled triangle, having zero width at water level and a base width b at bottom, i. Concrete gravity dam of constant height resting on a. Dynamic analysis of hirakud dam due to seismic forces. This type of a structure is most durable and solid and requires very less maintenance.
Aug 03, 2017 dam with water at its full reservoir level is subjected forces due to iwater pressure. A gravity dam is a concrete structure designed so that its weight and thickness insure stability against all the imposed forces. Ppt gravity dam powerpoint presentation free to view id. The complex nature of a gravity dam including its galleries, drain holes, roads and ancillary buildings, the variable nature of concrete, the heterogeneous foundation, the indeterminacy of the forces acting on the dam including the restraint of the foundation and abutments, all lead to a three dimensional problem as complex and insolvable in exact terms as could possibly be met in. Forces acting on a gravity dam gravity dam computation of. A force of 1 lbf causes a mass of 1 lbm to accelerate at 32. Design of gravity dam, calculation in reservoir full. 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 self. The pressure due to this seepage is commonly called hydrostatic uplift and will reduce the stability of the dam against sliding and against overturning. On december 10, 1967, at 22 h 5 min gmt, western india was shaken by a severe earthquake. To prevent sliding the contact with the foundation and the foundation itself must have appreciable shear strength. The inward compression of the dam by the water reduces the lateral horizontal force acting on the dam. Forces acting on a gravity dams with diagram geography. Pdf hydrodynamic forces on gravity dams with realistic modelling.
Gravity dams are designed so that each section of the dam is stable and independent of any other dam section. Horizontal pressure by the water at the upstream and downstreamtail water. Sliding force refer the contraction between the dam foundation and rock. Learning outcome after this lecture, students should be able to 1. Design and construction of concrete gravity dams nptel. This coastal and hydraulics engineering technical note chetn demonstrates a means of calculating hydraulic forces acting on submerged surfaces of hydraulic structures. 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. Gravity dam resists all external forces acting on it by selfweight. Previous ferc gravity dam guidance dealt with nappe forces by ignoring the weight of the nappe on top of the structure and by requiring that the. A gravity dam can be combined with an arch dam into an arch gravity dam for areas with massive amounts of water flow but less material available for a purely gravity dam. Over flow dam non over flow dam concrete gravity dam.
Dam with water at its full reservoir level is subjected forces due to iwater pressure. Adi forces acting on gravity dam ce in hindi youtube. Online courses for civil engineering covering full. The intensity, direction and location of these forces mu st be estimated by the engineer after consideration of all available facts and, to a certain extent, must be based on judgment. Grand coulee dam usa, nagarjuna sagar dam india and itaipu dam between brazil and. The purpose of this manual is to provide technical criteria and guidance for the planning and design of concrete gravity dams for civil works projects. Forces acting on gravity dams 1 free download as word doc. In this regard, dam foundationreservoir interaction can be seen as one of the most significant concerns for the determination of dam safety.
Gravity dam design united states army corps of engineers. The epicentre of the shock was computed by the us coast and geodetic survey at about 17. The principle force acting on a dam is the weight of the water behind the dam. Gravity dam loads on concrete dams loads can be classified in terms of applicabilityrelative importance as primary loads, secondary loads, and exceptional loads. Pdf dams are structures used thoroughly in the modern civilization to control some aspects of a water reservoir or water course. Gravity dam is so proportioned that its own weight resists the forces acting upon it. Calculating forces on components of hydraulic structures.
Determination of various forces which acts on the structure is the first step in the design of dams. Concrete dam engineering 1 0401544 hydraulic structures university of sharjah dept. Seismic response evaluation of a concrete gravity dam. Response spectrum analysis of concrete gravity dams. These forces are considered to act per unit length of the dam. Structural analysis of a gravity dam using finite elements. Many of the forces which must be cons idered in the design of the gravity dam structure are of such a nature that an exact determination ca nnot be made.
Since gravity dams must rely on their own weight to hold back water, it is necessary that they are built on a solid foundation of bedrock. Gravity dam a gravity dam has been defined as a structure which is designed in such a way that its own weight resists all the external forces. Introduction a typical crosssection of a gravity dam is the upstream face may kept throughout vertical or partly slanting for some of its length. Different types of forces acts on a dam structure such as water pressure, self weight, wave pressure etc. Therefore, these forces must be conservatively estimated when used as a stabilizing force in a stability analysis.
Tech civil engineering final year last semester numerical on gravity dam video link. Sd0710 a free powerpoint ppt presentation displayed as a flash slide show on id. Pdf on december 10, 1967, at 22 h 5 min gmt, western india was shaken by a severe earthquake. If there is water standing on the downstream side of the dam. Middle vaitarna dam submitted in partial fulfillment of the. All the predominant forces that act on the dam have been shown in the figure itself. Lake mead pushes against the dam, creating compressive forces that travel along the great curved wall. The weight of a gravity dam and the width of its base prevents it from being overturned when subjected to the thrust of impounded water kennard, 1995. Failure of gravity dam occurs due to overturning, sliding, tension and compression. The dam must be strong and sturdy and have strong connections to the ground, in the form of foundations, to help it stand.
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