Components of a DAM -- Detain, Accomodate, Maintain water
Components of Dam
Silt Pressure – Miscellaneous force coming on the dams on its upstream side. When water comes from catchment to water reservoir there will be lot of silt and get deposited and pile up at the bed of reservoir as the dam retains water reducing the velocity of water flow. Dredging is used to reduce silt pressure. By dredging you can get more effective depth to store water.
Uplift pressure and water pressure is resisted by self-weight of the dam. Dam will tend to turn about its toe because of the water pressure a clockwise moment, an uplift pressure a clockwise moment, it must be resisted by the vertical downward load an anticlockwise moment.
Limiting height of the dam is the maximum height of the dam at which it will not overturn designed looking at the elementary profile. Dam having less than a limiting height is called a low dam. Natural practice is to have actual height of dams more than limiting height which are called high dams.
To accommodate shutters, vehicles, platforms you need a width at the top of the dam. Practically elementary profile of dam is not in existence. In existence we have only practical profile of the dam. There are two types of practical profile of dams one is overflowing type, and another is non-overflowing type. Usually, dams will be non-overflowing type.
Total height of the dam = Maximum water level + tolerance for the FRL (full reservoir level) + tolerance for safety.
Design of dam is nothing but designing of base width of dam, designing height of the dam, designing the top width of the dam, designing the side slope of the dam.
The cavity designed inside the dam for inspection of dam is called the drainage gallery. Alteration to alignment of the dam, verticality of dam is inspected. Drainage gallery drains the reduces the uplift pressure. It is situated in the base of the dam. Any cracks detected can be grouted which is injecting cement to fill the cracks. Maintenance of dam is possible with this drainage gallery.
Dam shutters numbers will be selected according to requirements of discharge of water. Frequent shutter opening, greasing the rails for smooth lifting and lowering of shutters, is part of regular maintenance.
A sluice is a water channel controlled at its head by a gate. Under sluices for irrigation as well as for power generation. Covering sluices are also there for silt removal. Penstock is a pipeline connected to turbines. Three types of turbines the Pelton, Francis, and Kaplan turbines. Kaplan turbine is for low head, high speed. Francis turbine for medium height, medium speed. Pelton turbine for high head, low speed.
Intake structures of a dam for taking water and that will be used for domestic water supply. Water will be taken to treatment plant on the downstream side.
There will be set up for domestic purposes, electric power, irrigation, drainage excess water. Spillways once opened water directly goes to river and on either side of river you have canals. Stilling basin with baffle walls by which water will come to a still hence the name.
Fish ladder in the downstream of the dam through which fishes collected in upstream will come to downstream when shutters are open. Fish will come to stilling basins. From stilling basin there will be a small ramp with grids from the downstream side to the upstream side. Fish ladder also enables fish to go to the upstream.