 |
New Targets for Three Gorges Project
Highlights: Eight years have passed since the beginning of the construction period of the Three Gorges Project in 1993. In the cross-century construction of this project, there are three important phased targets: First, the damming of the Yangtze River in 1997; Second, power generation by the first group of generating units in 2003, opening permanent ship-locks to navigation and the initial water storage of reservoirs; and third, the completion of the entire project in 2009.
The second target to be met in the next step is the crucial target of most important, turning-point significance.
Following is the text of this report written by Xinhua correspondent Shi Yongfeng
INSPRING TARGETSWhat does the 2003 target mean to the Three Gorges Project?
Firstly, power generation by the first group of generators will begin in 2003 for the Three Gorges Project. According to the preliminary design of the project, two generators in the first group of machine sets are designated to generate power.
Thanks to the smooth progress of the project, the project now decides that power generation by the first group of machine sets in 2003 will be arranged in accordance with the principle of getting three and striving for four to five generators of the first group of machine sets in 2003 to generate electricity.
The installed capacity of each of the Three Gorges machine units is 700,000 kw. Calculated on the basis of the electricity generated by four generators, the electricity volume provided a year will amount to around 13 billion kwh, almost equivalent to the total amount of power generated by the Gezhouba Project, so it will provide enormous electricity support to the economically developed but energy-deficient regions of east, central and south China.
Secondly, the permanent ship-locks of the Three Gorges Project will be opened to navigation in 2003. These ship-locks are the largest in the world, capable of allowing the passage of 10,000-ton-class fleet of ships. The ship-lock consists of five tiers, with the two-wire length totaling 6.4 kilometers and the largest drop between the upper and lower reaches reaching 113 meters, that is to say, a ship, when passing through the permanent ship-lock, has to cross the height of a 50-storied building.
The Three Gorges Project has also installed a ship lift capable of allowing the speedy passage of passenger or cargo ship, this world's largest ship lift is big enough for the passage of a 3,000-ton-class passenger ship or freighter at one time.
Thirdly, in 2003, the Three Gorges Reservoir will be able to store water up to 135 meters above sea level. The water table before the Three Gorges Dam will be raised by about 80 meters. Then, the rapid, narrow river will become broad and flat, thus freeing ships from the threats of hidden shoals and dangerous reefs and making sailing in the Three Gorges more safe and convenient.
UNPRECEDENTED CHALLENGESWith the setting of the three major targets of power generation, navigation and water storage, placed before the over 10,000 builders of the Three Gorges Project is a new unprecedented challenge posed by difficulties.
In terms of difficulties in construction, the most arduous task involved in the Three Gorges Project is the dam concrete depositing of high intensity and high requirement. In the eight years since the start of the Three Gorges Project construction, the first six years were mainly involved in earth and stone work, it was only till 1999 that large-scale dam concrete placing work began.
Although high-intensity concrete pouring work for the Three Gorges Project was carried out between 1999 and 2000 and new world records were repeatedly set, beginning from 2001, however, dam concrete deposit for the project not only has to be maintained at a high intensity of over 4 million cubic meters a year, but also began a complete entry into the complex position of guiding flow to bottom and deep holes and sluice gates, not only difficulty in concrete pouring has rapidly increased, but this work has to be carried out alternately with the burying of metal parts and the installation of machine units, these two types of work interfere with each other, making construction extremely difficult, this situation of difficult construction will continue all the way through to the end of 2002.
At present, the second-phased dam water checking front edge reaches a 120 meter elevation on average, by the end of this year, dam concrete-pouring will have reached an average 140-meter elevation, by October 2002, the second-phase dam concrete depositing will have reached 185 meters, the height of the top of the final dam, then it will possess the conditions for water storage and power generation.
Under the conditions of high intensity, pressing construction period and complicated construction work, how to complete the dam concrete pouring work in high quality is the most severe challenge facing the Three Gorges Project in 2003.
The Three Gorges' power generating units with the largest generating capacity in the world are now being manufactured by 14 factories in seven countries. For the need of flood control and sand discharge, the water-head change rate of the running of power generating units reaches 52 meters.
Under the condition of such a huge water table change rate, the generating units have to run steadily and possess the properties of good efficiency and cavitation, this set special demands on the manufacture and installation of machine units, the difficulties involved surpass any large machine unit in the world. The manufacture, installation and debugging of the Three Gorges extra-large machine unit is a project involving the most difficult technical problem facing the Three Gorges Project before 2003, which is faced with a series of challenges.
Before 2003, the Three Gorges Project will face another challenge, that is, construction of another Yangtze river dam project will be carried out in December 2002.
Because of the need of flow passage and navigation of the Yangtze River, the concrete pouring work will be carried out in two stages for the second- and third-phase schemes of the 2,300-meter-long Three Gorges Dam. The completion of the Yangtze Dam of the Three Gorges Project on November 8, 1997 was aimed at building the approximately 1,600-meter-long second-phase Dam. The construction of an over 900-meter-long Third-phase Dam requires damming the river second time. Because the second damming has to be carried out on a flow-guiding open canal of only 350 meters wide, so the difficulty involved will be higher than that in the first damming of the Three Gorges Project and the damming of Gezhouba Project.
Experts say that the designed runoff of the second dam of the Three Gorges Project will reach 12,200 cubic meters per second, with the fall reaching 5.4 meters. At present, designing and scientific research units of the Three Gorges Project are organizing second damming tests and tackling designing and technical problems.
Despite the series of unprecedented challenges posed by difficulties, the broad masses of the Three Gorges Project builders are confident and capable of surmounting every difficulty. When interviewed recently by reporters, an official with the China Yangtze Three Gorges Project Development Corporation indicated that the three major targets set for the Three Gorges Project in 2003 will certainly be met.
In This Section
|