1. Spillway The Three Gorges Project is designed with a
concrete gravity dam with a crest elevation of 185 meters and maximum height of
175 meters. The dam axis runs 2, 309. 47 meters long, which is even longer than
the noted Grand Coulee Dam of US.
The 483-meter spillway, located in the middle of the main dam, has 23 bottom
outlets dimensioned at 7?Ã¡9 meters. Each of its 22 surface sluice gates
measures 8 meters wide. The maximum discharge capacity of the TGP is 116,000
cubic meters, the biggest in the world.
2. Left Powerhouse Two powerhouses, flanking the
spillway, accommodate altogether 26 sets of turbine-generators. As the world's
biggest unit ever made, each has a generating capacity of 700MW. The
643.6-meter-long left powerhouse, 60 meters longer than the 584.2-meter-long
right one, houses 14 sets of generators. With all these huge generators, the TGP
is designed to generate electricity of 84.7 TW/h.
3.Right Powerhouse On the right bank, enough room has
been preserved for the future underground powerhouse of 6 turbine generator
units with 4, 200 MW of installed capacity. The intakes of these units will be
constructed simultaneously with the project.
4. Shiplift The TGP shiplift is the world's largest. With
a one-step vertical hoisting mechanism, the ship lock, equipped with a
120?Ã¡18?Ã¡3.5-meter container, is capable of carrying a 3,000-ton passenger
liner or cargo boat at a time.
5.Temporary Ship lock A temporary ship lock was built
during the TGP construction period with an effective chamber at 240?Ã¡24?Ã¡4
6.Permanent Ship lock The Three Gorges Project (TGP)
permanent ship lock is designed in a two-way, five-step pattern with each lock
chamber measuring 280?Ã¡34?Ã¡5 meters (L?Ã¡W?Ã¡D) and capable of passing a
10,000-ton barge fleet.
7.Dam Site After a long but prudent study on 15
alternatives, the dam site for Three Gorges Project was finally determined at
Sandouping, where a number of favorable factors gather at the small town 30
kilometers west to the Yichang city. Sandoupin has a firm crystalline rock
foundation, which is the most important geological condition a massive hydraulic
project required of. The River valley here at Sandoupin is much broader than
other site alternatives and hills on each sites lower. A small islet, called
Zhongbaodao by locals and cleaving the Yangtze River at its center, offers the
most favorable pattern for the river diversion needs scheduled in the first
phase of the TGP. The bedrock of the dam site is sound and intact granite
with 100 MPa of compressive strength. The faults and fissures in the bedrock are
less developed and most of them are well cemented. The permeability of the rock
mass and the weathered layers in the hills on both sides are also ideal. No
potentially devastating geological structures was detected within 15 kilometers
of its vicinity. The regional seismic activities are small and not frequent.