About Dams
Construction sequence for Three Gorges Dam
The Three Gorges Dam is a gravity dam constructed from concrete. Each diagram on this page shows the plan of the dam site.
Stage 1
A
cofferdam
is formed on one side of the river by dumping rocks into
the water to create an embankment
dam.- Water is pumped out from the enclosure formed between the riverbank and the dam to create a dry pit.
- The pit is excavated to a deep enough level so that all of the river water can be diverted through it during Stage 2 of the construction.
- A concrete cofferdam is constructed along one side of the pit.
Stage 2
Two
more rockfill
cofferdams are constructed on the other side of the river,
again by dumping rocks in the water, one upstream of the
dam location and one downstream- These form an enclosure with the river bank and the Stage 1 concrete cofferdam. The enclosure is then pumped dry and excavated, so that the first portion of the main dam can be built within it.
- Meanwhile, the water flows through the deeper channel on the other side of the river formed during Stage 1.
Stage 3
Two
more rockfill cofferdams are constructed to create a final
enclosure, which is pumped dry and excavated to complete the
construction of the dam across the river.