A gravity dam is a large dam made of masonry, concrete or stone. They are designed to contain large volumes of water. By using these materials, the weight of the dam alone is able to resist the horizontal pressure of the water pushing against it. Gravity dams are designed so that each section of the dam is stable and independent of any other section of the dam.[1]​.

The most common classification of gravity dams is by the materials that make up the structure:

Composite dams are a combination of concrete dams and embankments. The construction materials for composite dams are the same used for concrete dams and embankments. Folsom Dam") is a composite dam.

Gravity dams can be classified according to plan (shape):

Gravity dams can be classified with respect to their construction height:.

Contenido

Las presas de gravedad se construyen cortando primero una gran parte del terreno en una sección del río, lo que permite que el agua llene el espacio y se almacene. Una vez cortado el terreno, hay que analizarlo para asegurarse de que puede soportar el peso de la presa y del agua. Es importante asegurarse de que el suelo no se erosionará con el tiempo, lo que permitiría al agua abrirse paso alrededor o por debajo de la presa. Normalmente el suelo es suficientemente fuerte para lograr estos objetivos, sin embargo, otras veces es necesario acondicionarlo añadiendo rocas de apoyo que refuercen el peso de la presa y del agua. Existen tres pruebas diferentes para determinar la resistencia de los cimientos: la de Westergaard, la euleriana y la lagrangiana. Una vez que los cimientos son adecuados, puede comenzar la construcción de la presa. Normalmente, las presas de gravedad se construyen con un material resistente, como hormigón o bloques de piedra, y tienen forma triangular para proporcionar el máximo soporte.[3]​[4]​.

Earthquakes

Gravity dams are built to withstand some of the strongest earthquakes. Although the foundations of a gravity dam are built to support the weight of the dam and all the water, they are quite flexible, absorbing a large amount of energy and sending it to the Earth's crust. A gravity dam has to be able to absorb the energy of an earthquake because, if the dam were to break, it would send a large amount of water downstream, destroying everything in its path. Earthquakes are the greatest danger to gravity dams, so every year, and after every major earthquake, they must be tested for cracks, durability and strength. Although gravity dams are expected to last between 50 and 150 years, they must be maintained and replaced periodically.[5]​.