对三峡工程三期截流的几点认识

Some recognitions on TGP's 3rd-stage river closure work

三峡工程三期截流 ,流量为 12 2 0 0m3 /s ,落差为 5 .77m ,此截流工程将是目前世界上综合难度最大的截流工程。依据三峡工程 1/ 80整体截流模型的试验成果及以往葛洲坝等工程的研究成果 ,对三期截流方案 ,防止抛投体流失的措拖 ,及垫底结构形式、施工时机等问题进行了讨论。认为 :三峡三期截流方案以双戗截流为好 ;龙口先平抛垫底加糙可以有效地防止抛投料的流失 ;为确保垫底施工成功 ,垫底施工期在今冬明春为好 ;目前 ,2 0t混凝土四面体加 3～ 5t大块石的垫底结构可基本满足渡汛的要求。

The suggested discharge for 3rd-stage river closure of TGP is 12 200 m3/s, and the final water drop is 5.77 m, thus, the closure work will be the largest one of comprehensive difficulties in the world. On the basis of primary test results on integrated closure model of TGP with a scale of 1:80 and the experience of Gezhouba Project's river closure, some problems, including 3rd-stage closure schemes, measures preventing the lose of riprap blocks in moving water, structure form of bedding course and its construction period selection, etc., are discussed. It is considered that: end dumping with double dykes is a preferable scheme; bedding course horizontally filled in advance with concrete blocks and stone materials for roughening the river bed may effectively prevent the lose of dumped materials; to guarantee the success of construction of bedding course, its construction period should be selected at winter 2001 to spring 2002. At present, the bedding course structure formed by 10 t-concrete tetrahedrons and large block stones weighing 3-5 t may meet the requirement for stability in flood season. But it is needed further study to be optimized.