April 2, 2002
Small cracks in the Three Gorges dam discovered in 1999 have multiplied and grown. Construction officials say that although they regret not having taken the problem seriously at first, it is now being fixed.
[Small cracks in the Three Gorges dam discovered in October 1999 have multiplied and grown. Some now extend from the top to the bottom of the huge concrete structure and as far as two metres into it. Construction officials say that although they now regret not having taken the problem seriously at first, they are lucky to have detected it early on and that it is being fixed. The following is a translation of an article on the problem that appeared on March 11 in South Wind Window (Nanfeng Chuang), a popular magazine and sister publication of Guangzhou Daily (Guangzhou Ribao). The article was also reprinted on the Web site of the Changjiang Water Resources Commission.]
It has been rumoured for the past several years that cracks have appeared in the Three Gorges dam. The Beijing media have even been quoted as asking, ‚”Can the dam still hold water, given that it is cracked?”
With this question in mind, a reporter from South Wind Window (Nanfeng chuang) travelled to the dam site to investigate. There, it can be seen that part of the dam has been built up to its greatest height –185 metres above sea level. In the central area of the dam, on the upstream face, about 23 sections of scaffolding have been built. Below these, a ditch hundreds of metres long and tens of metres deep has been dug along the foundation of the dam. There, a group of workers is busy repairing cracks on the surface of the dam.
The cracks can be seen stretching from the top to the bottom of the dam, and some are wide enough to accommodate an adult’s hand. Asked why these cracks have appeared, a worker who appeared to be in charge of the repairs said: “It seems that something went wrong with the material in the partition boards separating the different sections during the concrete-pouring work. There was probably also some problem with the foundation of the dam.”
Wang Jiazhu, vice-president of the Three Gorges Project Development Corp., spoke about the issue at a small news conference at the dam site to which Chongqing and Hubei officials and domestic reporters were invited on Feb. 11.
“The construction of the Three Gorges dam has been proceeding in the right direction for nine years, but there have been flaws, accidents and so forth, some of which are actually very serious,” Mr. Wang said.
“For instance, the surface of the bottom outlets [in the spillway section] is not very level and smooth, partly because they are built on stilts, an issue we have been addressing for more than a year. The cracks on the upstream face of the dam were discovered in October 1999. At that time just one crack was found, with a depth of only 0.1 to 0.2 millimetres. But later more cracks were discovered, and they became so deep that some of them extended for more than two metres into the dam.”
Asked whether the problem was so severe as to warrant dismantling the dam completely and starting again, Mr. Wang said: ‚”It is true that the problem will have a significant effect on the construction timetable, especially this year’s schedule, given that we are going to dam the river again in November. We’re lucky to have discovered the problem early on, because we have had time to take remedial action. But from now on, we need to be more careful. If something like this goes wrong in the near future, we will have no time to address it because of the tight schedule decided on by the central government.”
Pen Qiyou, another high-ranking Three Gorges corporation official, said: “Cracks in a dam such as the Three Gorges are unavoidable. The question is whether the cracks will hurt the project itself. Based on an inspection by dam experts, the current cracks are not serious enough to harm the dam. However, it is highly likely that they could develop into harmful cracks if not repaired quickly and thoroughly.”
Zhang Chaoran, chief engineer of the Three Gorges corporation, offered further details: “By consulting several leading dam experts in China, we were able to determine that, first, the cracks are caused by variations in temperature during the concrete pouring, and that they are superficial; second, after repairs, the dam will be up to standard in terms of project design and future operation. As a matter of fact, this is a normal phenomenon, and cracks such as these can be observed in almost all large dams around the world.”
“Our problem was that we failed to take them seriously at first. We didn’t think they would develop so quickly or so dramatically, beyond our expectations. However, I should add that we never tried to cover up the problem, but instead reported it immediately to Qian Zhengying, vice-chairman of the Chinese People’s Political Consultative Conference and head of the Three Gorges project quality inspection group.”
“In fact, we have paid a great deal of attention to addressing problems with the construction of the dam. For example, it is our policy to offer rewards to anyone who discovers quality-control problems while building the dam. More importantly, we have taken a series of effective measures to tackle the problem of the cracks by deploying more engineers and workers, employing more advanced technologies and better materials, and introducing higher quality-control standards.”
“In addition, we have had everything inspected at the construction site in an effort to find any cracks or flaws on the surface of the dam, in the shiplock, almost everywhere at the site. We are expecting to complete the repair work by the end of March this year, and then to have it checked by an inspection team organized by the State Council. Of course, we won’t dare to fill the reservoir before the State Council inspectors sign off on our work. We believe we can fix the cracks and that we will encounter no other such problems, fulfilling our commitment to the State Council to build a first-class dam by eliminating all hidden troubles.”