Concrete dams are divided into three types: gravity dams, arch dams and buttress dams.

① Gravity dam: It relies on the friction generated between the dam body's own weight and the foundation to withstand the thrust of water and maintain stability.

The advantages of gravity dam are simple structure, easy construction, good durability, suitable for high dam construction on rock foundation, and convenient for setting up water release structures. However, the gravity dam is large in size, uses a lot of cement, and the material strength cannot be fully utilized.

② Arch dam: It is a space shell structure with an arch shape on the plane and bulges upstream. It uses the function of the arch to convert the horizontal load it bears into axial pressure and transmit it to the bedrock on both sides. The abutment supports the dam body and keeps the dam stable. Arch dams have high overload capacity. Arch dams have higher requirements on foundations and rocks on both sides, and their construction is more difficult than gravity dams.

Narrow valley dam sites with hard and complete rock foundations on both sides are particularly suitable for building arch dams. Generally, if the ratio of the dam bottom thickness T to the maximum dam height H (T/H) is less than 0.1, it is called a thin arch dam; if it is between 0.1 and 0.3, it is called an arch dam; and if it is between 0.4 and 0.6, it is called a gravity arch dam. If the T/H value is larger, the effect of the arch is very small, that is, it is close to a gravity dam.

③Buttress dam: It consists of inclined cover surface and buttresses. The buttresses support the cover, and the water pressure is transmitted from the cover to the buttresses, and then from the buttresses to the foundation. Buttress dam is one of the most economical and reliable dam types. Compared with gravity dams, it has the advantages of small size, low cost, and strong ability to adapt to the foundation.

According to the cover form, buttress dams can be divided into three main types: those with a flat cover are called flat dams; those with an arched cover are called continuous arch dams; those with a cover made of buttresses The thickened upstream end is called a big head dam. Buttress dams are generally concrete or reinforced concrete structures.

Compared with gravity dams, buttress dams have the following characteristics: the upstream cover is often tilted, and the weight of water on the cover can help stabilize the dam; buttress dams have thin components, uniform internal stress, and can Give full play to the strength of the material; the lateral stiffness of the buttress is small, and the working conditions of the buttress during lateral earthquakes should be checked during design; buttress dams have higher requirements for foundation conditions than gravity dams.

Extended information

The safety and reliability calculation of concrete dams is mainly reflected in two aspects:

① The dam body is along the dam base surface, the bank slopes on both sides of the dam base or The sliding stability along the weak structural plane in the rock mass has sufficient reliability.

②The strength of each part of the dam body is sufficiently guaranteed.

Concrete dams began to appear in the late 19th century and developed rapidly. In 1936, the United States built the Hoover Dam with a dam height of 221.4m and a volume of 3.36 million m2. It is a typical representative of modern concrete dams. Its main signs are:

① Establishing a more practical dam Dam body stress analysis method.

②Adopt a more reasonable dam structure.

③ Proposed a more complete construction method and adopted corresponding construction equipment.

④Complete measures to control concrete cracking have been formulated.

⑤ Use safety factor to coordinate the relationship between safety and economy. Most of the dams built around the world with a height of more than 100 meters are concrete dams. After the 1960s, due to improvements in construction technology and mechanization, the construction technology of earth-rock dams has been developed, and the proportion of concrete dams has declined.

However, with the continuous innovation of concrete dam design concepts, especially the development of roller compacted concrete dam construction technology, concrete dam construction will create broader prospects.

Baidu Encyclopedia - Dam

Baidu Encyclopedia - Concrete Dam