CRITERIA FOR DESIGN OF EARTH DAMS

The criteria for the design of earth dams are: 1. Sufficient spillway capacity and freeboard are provided so that there is no danger of overtopping of the dam 2. Seepage flow through the embankment is controlled so that the amount lost does not interfere with the objective of the dam and there is no erosion(…)

EARTHFILL DAMS & ITS CLASSIFICATION

Earthfill dams are the most common type of dam built to any height. They are designed as a non-overflow section with separate spillway. The reason for such wide spread use of earthfill dams are: The foundation requirements are not as rigorous as other dams Local available soil is the main construction material High skill not(…)

A cofferdam is a temporary structure designed to keep water and/or soil out of the excavation in which a bridge pier or other structure is built. Types of Cofferdams Braced Earth-Type Timber Crib Double-Walled Sheet Pile Cellular Braced Cofferdams Formed from a single wall of sheet piling Drive into the ground to form a box(…)

Environmental Impacts of Large Dams

Dams have both intended and unintended impacts, which can be positive or negative. It is unlikely to find intended negative impacts, though positive impacts can be both intended and unintended. Each of these types of impacts can be inevitable in their entirety, reducible or totally avoidable. Most adverse social and environmental impacts of large dams(…)

FORCES ACTING ON A DAM STRUCTURE

In the design of a dam, the first step is the determination of various forces which acts on the structure and study their nature. Depending upon the situation, the dam is subjected to the following forces: 1. Water pressure 2. Earthquake forces 3. Silt pressure 4. Wave pressure 5. Ice pressure 6. Self weight of(…)

ANALYSIS OF GRAVITY DAM

The stability of a dam can be analysed in the following steps: i. Consider unit length of the dam. ii. Work out the magnitude and dimensions of all the vertical forces acting on the dam and their algebraic sum, i.e. ?V. iii. Similarly work out all the horizontal forces and their algebraic sum i.e. ?H.(…)

STRUCTURE OF A GRAVITY DAM

STRUCTURE (PARTS) OF A GRAVITY DAM Heel: contact with the ground on the upstream side Toe: contact on the downstream side Abutment: Sides of the valley on which the structure of the dam rest Galleries: small rooms like structure left within the dam for checking operations. Diversion tunnel: Tunnels are constructed for diverting water before(…)

CLASSIFICATION (TYPES) OF DAMS

CLASSIFICATION (TYPES) OF DAMS BASED ON PURPOSE 1. STORAGE DAM OR IMPOUNDING DAM 2. DETENTION DAM 3. DIVERSION DAM 4. COFFER DAM 5. DEBRIS DAM 1. STORAGE DAM OR IMPOUNDING DAM It is constructed to create a reservoir to store water during periods when there is huge flow in the river (in excess of demand)(…)