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Cracks in hydro-power dam harmless: Experts
The Electricity Group of Vietnam (EVN) has submitted reports from both domestic and foreign experts, confirming that cracks in the dam at the Son La hydro-electric plant are harmless, to the State Council responsible for the project, the biggest of its kind so far in Vietnam.
EVN, the project’s investor and manager, reported that inspections have revealed that the cracks are simply the result of temperature differences between the surface and the interior of the concrete during the early stages of construction. They merely penetrate the surface of the concrete panels, and are no threat to the stability and impermeability of the dam.
EVN has based its report on its consultations with leading international firms, such as Colenco, from Switzerland and SMEC-NIPPON KOEI-JPOWER, from Australia and Japan.
At a recent symposium regarding the matter, representatives from these companies gave presentations on the probable causes and the possible impact of the cracks upon the safety of the dam, and came to similar conclusions.
EVN has also taken core samples of the dam’s roller-compacted concrete (RCC) to perform quality analyses.
The test results confirmed that the RCC meets the technical and safety standards for the dam.
The concrete dam at the Song La hydro-electricity project, at over 138m high, was constructed using almost 3.1 million cu.m. of concrete.
By Feb. 15, almost half of the concreting had been completed.
EVN said that all possible care was taken during the pouring of the concrete, with regular temperature readings being recorded before and during the process and the time period between layers of concrete being strictly monitored.
The cracks were discovered while executing the dam and were instantly recorded in an official document, which was signed by representatives of the investors, design consultants and supervisory agencies.
EVN said it immediately conducted inspections and primary evaluations, ensuring that the design consultants supervised any test drillings, reported on the probable causes and proposed solutions to prevent the remaining concrete from suffering a similar fate./.
Vietnamplus
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