Dam of the Three Gorges Project
( 2003-07-03 15:01) (Chinadaily .com.cn)
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?á9 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 shiplock, equipped with a 120?á18?á3.5-meter container, is capable of
carrying a 3,000-ton passenger liner or cargo boat at a time.
5.Temporary Shiplock
A
temporary shiplock was built during the TGP construction period with an
effective chamber at 240?á24?á4 meters.
6.Permanent Shiplock
The Three Gorges Project (TGP)
permanent shiplock is designed in a two-way, five-step pattern with each lock
chamber measuring 280?á34?á5 meters (L?áW?áD) 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.
|
