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A
concrete gravity dam, 1210 meters (3970 feet) in length and
with a maximum height of 163 meters above the deepest foundation
level, is under construction across river Narmada.
The dam will be the third highest concrete dam (163 meters)
in India, the first two being Bhakra (226 metres) in Himachal
Pradesh and Lakhwar (192 meters) in Uttar Pradesh. In terms
of the volume of concrete involved for gravity dams, this
dam will be ranking as the second largest in the world with
an aggregate volume of 6.82 million cu.m. The first is Grand
Coule Dam in USA with a total volume of 8.0 million cu.m. This
dam with its spillway discharging capacity of 87,000 cumecs
(30.70 lac), will be the third in the world, Gazenba (1.13
lac cumecs) in China and Tucurri (1.0 lac cumecs) in Brazil
being the first two.
For chute spillway Radial gates, 7 in number and size 60'
x 60' and for service spillway, 23 Radial gates of size 60'
x 55' are to be provided to negotiate the design flood. 10
number of temporary construction sluices, each of size 2.15
m x 2.75 m. are provided in the boby of the spillway at RL
18 m. Another set of 4 permanent river sluices are provided
at RL 53.0 m. The lower sluices were closed in February, 1994.
The design of the dam allows for a horizontal seismic coefficient
of 0.125g and it also covers an additional risk due to reservoir
induced seism city. Most sophisticated seismological instruments
for monitoring and evaluation of the stresses in the body
of the dam as whell as the effect on the periphery of the
reservoir are under installation.
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