Which type of dam is constructed as a concrete or masonry wall across a valley?
A) Arch Dam
B) Gravity Dam
C) Embankment Dam
D) Buttress Dam
The correct answer and explanation is :
The correct answer is A) Arch Dam.
Explanation:
An Arch Dam is a type of dam that is typically constructed as a concrete or masonry wall across a valley or canyon. The design of an arch dam relies on the strength of the material to withstand the water pressure and channel it towards the abutments, where the forces are transferred. The arch shape of the dam allows it to efficiently transmit the forces of the water to the rock formations or other structures at the sides of the valley. This design is particularly beneficial when the valley has a narrow, steep, or rocky profile, which can support the arch structure effectively.
Here’s a breakdown of how arch dams work and why they are used:
- Design and Materials: Arch dams are usually made from concrete or masonry and are constructed in valleys with steep, hard rock formations. The arch shape of the dam is designed to transfer the load of the water directly to the valley’s sides. The material’s inherent strength allows the dam to withstand significant water pressure.
- Efficient Use of Material: The arch design minimizes the amount of material needed compared to other dam types. Since the force is transferred to the abutments, a thinner structure can support the same volume of water as a thicker dam, making it an efficient choice when constructing in narrow valleys or where material is limited.
- Hydraulic Pressure Management: Water pressure on an arch dam is primarily directed along the curves of the dam towards the valley walls, reducing the need for extensive foundational support. This makes arch dams ideal for locations where the geological conditions support this kind of load distribution.
- Applications: Arch dams are typically used in narrow canyons or valleys where the topography supports the construction of a curved structure. They are also chosen when the dam needs to handle a large amount of water pressure without requiring large quantities of construction material.
In contrast:
- Gravity Dams rely on their weight to resist the force of the water, often used in wide valleys.
- Embankment Dams are made from earth materials and are typically used in wider or less steep areas.
- Buttress Dams have a sloping surface and are supported by multiple buttresses, providing strength without relying on a full solid wall.