Vajont_Dampowerpoint_14.pptx
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Transcript Vajont_Dampowerpoint_14.pptx
Group 14
Angelina Hand
Mark Kelly
Lydia Rooney
Seán Stapleton
Vajont Dam, Italy
100km north of Venice
Constructed between 1956 and 1961
Built to provide power to Milan, Modena and Turin
Largest double-arched dam in the world when it was
completed
One of UNESCO’s five worst man-made disasters
caused by engineers and geologists!
Design
262m tall
27m thick at base and 3.4 m thick at top
150 million m3 of water retained
behind the dam
360,000m3 of
reinforced
concrete
Signs of Failure: Construction
Phase
Concerns for stability of valley walls during
construction
Tests showed possibility of ancient landslide on right
bank
Concluded that smaller slides in looser surface layers
were likely
BUT that deep seated landslides would be extremely
unlikely!
Signs of Failure: Filling of the
Reservoir
March 1960: First small landslide occurs
October 1960: Rate of displacement of 3.4cm/day
November 1960: Large landslide
Engineers realised that the large mass of the left bank was
unstable
Used varying levels of water and drainage tunnels to gain
control of the sliding mass
For the next two years dam was drained down and filled up
3 times to control the creep rate to avoid failure
Failure
October 9th 1963: Landslide occurred
Mass of 260 million m3 slid into river at
110km/hour
Caused 50 million m3 of water from the reservoir
to be swept over dam in a 250 m high wave
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Over 2000 lives lost
5 villages destroyed
Dam remained fairly intact
Only top 1m washed away
Causes of Failure
Increased water levels caused increased pore water
pressure in clays
Reduced effective strength and shear resistance
When dam levels dropped, hydraulic pressures were
induced
Caused brittle failure and disastrous loss of strength
Conclusion
Safe and sound structure
BUT
Emphasis on impacts of construction on surrounding
environment
Importance of soil testing
Town planning development of escape routes and
protection from floods
Animation
http://www.youtube.com/watch?v=uqkFXm2HtMA&f
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