China Yangtze Three Gorges Dam The Yangtze River was completely blocked on Nov. 6, 2002 at the Three Gorges when the opening in the diversion canal of the Dam Project was closed. Hence the natural flow of the mighty river at the Three Gorges is cut. At the location of the Sandouping dam site, the river valley is relatively open and broad, with a small islet known as Zhoubaodao in the river, which is favorable for a river diversion scheme with phased construction. As regards communications, there is a railway to Yichang and a waterway to the dam site. A 26 km-long expressway has also been constructed from Yichang to the dam site. The bedrock at the dam site is sound, intact granite with a compressive strength of 100 developed. The rock mass has only very slight permeability.
Layout of Three Gorges Dam 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 79 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.
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. 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. Ship lift The TGP ship lift is the world's largest. With a one-step vertical hoisting mechanism, the ship lock, equipped with a 120*18*3.5-meter container, is capable of carrying a 3,000-ton passenger liner or cargo boat at a time. Temporary Ship lock A temporary ship lock was built during the TGP construction period with an effective chamber at 240*24*4 meters. 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 meters and capable of passing a 10,000-ton barge fleet. 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. Schedule of the Dam The Three Gorges Dam Project, which is the world largest water and power project, was kicked off on December 14,1994. The total construction period will be 17 years. Selection Of The Site Sandouping, 7 km from the entrance of Xiling Gorge at the lower reaches of the Yangtze River, was selected as the site of the Three Gorges Dam in 1959. The river here is much bigger than it is in other area. There is a small island named Zhongbaodao in the middle of this part of the river. It is the best choice of the site for the dam. The 1st Phase Of The Construction: 1993 - Nov.1997 The planning of the project was started in 1993. The actual building of the Dam started on 14 Dec. 1994. Zhongbao Island was used to build dyke A to dam the river water and to connect the right bank with the other dyke. In order to build the main part of the Dam and the diversion channel afterwards, foundation work B and foundation work C which is long and thin were built in the dry riverbed. At the same time, channel construction such as Lock D started. The 2nd Phase Of The Construction: Nov. 1997 - 2003 Dyke A was built and the left bank was connected to another dyke. Later, the flood-relief dam and the main part of the Dam B for the installation of generators were built in the dry riverbed and then, 14 generators were installed. Diversion Channel C was opened to navigation and it was dammed again in Nov. 2002. The 3rd Phase Of The Construction: 2003-2009 Diversion channel is dammed. Dyke A is being built and the right bank with the other dyke will be connected again. Reservoir begins to store water and generating set B on the left side will be put into operation. The five stage ship lock C will be put into operation. The main part of the Dam D for installation 12 generators is being built on dry riverbed. Completion: In 2009 The height of the Three Gorges Dam will be 185 meters. That would be the biggest dam in the world. All 26 generators will be put into operation by 2009. How to get there The dam site is 27 miles upstream from YichangCity proper, at
SandoupingTown, 38km upstream from the Gezhouba Dam Lock. It is very convinient to get there by ship from the cities along yangtze. Ship Most of the ships sail between Chongqing and Yichang, Shashi or Shanghai will stop here for an one-hour shore excursion. The avalibale luxury ships can be checked in the column of Yangtze Cruise. Bus: There is an express way connecting the dam site with Yichang. Travelers can take buses from Yichang to the Dam Site.