What is rockfill dam,Types of rockfill dam and design of rockfill dams ?

In this article we discussed what is rockfill dam,Types of rockfill dam and design of rockfill dams in detail.

What is a rockfill dam ?

• A rock fill dam, like an earth dam is composed of rock fragments with each particle independent of the other. 
• The mass stability of a rockfill darn is mainly developed by the friction and interaction of the particles. 
• A dense rockfill with well-graded rock fragments should be used. 
• Rocks are usually obtained by quarrying rocks. However, sometimes naturally occurring materials, such as talus, boulders, cobbles and coarse gravels, are also used. 
• The rockfill used in the dam should be capable of resisting erosion. Moreover, it should be strong enough to withstand very high stresses in wet conditions. Because the load due to water pressure is transmitted through the rockfill by rock to rock

A rockfill dam consists of two basic structural elements

1. An pervious element 
2. An embankment built of rock fill

Types of rockfill dams:-

1. Impervious membrane type
2. Earth core type

Components of the impervious memebrane type rockfill dams 

1. Impervious memebrane
2. Upstream cutoff
3. Upstream rock cushions or dry rubber masonry.
4. Main rockfill on the downstream

Types of the impervious membrane used in rockfill dams

1. Reinforced concrete facing
2. Asphalt concrete facing
3. Steel facing
4. Timber facing

Design consideration of the rockfill dams 

1. Top width
2. Free board
3. Slope and sections
4. Settlements
5. Axis of the dams