龙滩碾压混凝土重力坝设计

龙滩水电站大坝为碾压混凝土重力坝，最大坝高前期为192m，后期为216．5m，是目前世界上在建的最高的碾压混凝土坝。通过对原材料的选择和试验，确定了推荐配合比，大坝下部碾压混凝土采用富胶凝材料。大坝优化设计后，为经济的断面体形；坝基面及坝体的稳定、应力均满足规范要求。龙滩大坝除基础垫层外，均可采用碾压混凝土。坝体防渗结构优化后采用表面布筋的变态混凝土与二级配碾压混凝土组合方案；坝体设有完善的排水系统。温控防裂专题研究表明，采取适当的温控措施后，坝体可不分纵缝通仓浇筑。龙滩大坝设计中的重大技术问题已解决，部分专题仍在继续深入研究中。

Design of Longtan RCC Gravity Dam

The dam for Longtan Hydropower Project is a RCC gravity type, with a height of 192 m in the first stage and 216.5 m in the second stage, the highest RCC dam in the world. Many tests were carried out and the mix proportion of RCC was recommended. A large amount of indoor- and field-tests proved that it is proper and necessary that rich cementing materials should be applied to the middle and lower portion of the dam body. The optimized dam sections were economical. Both the stresses and the sliding stability of the dam could meet the requirements of the standards. RCC can be placed for the whole Longtan Dam from its crest to foundation layer, except its foundation cushion layer. Its impermeable structure is composed of GEVR combined with grade-2 RCC is recommended and a drainage system is provided. The study on the crack control and temperature control showed that the placing of RCC without longitudinal joint would be feasible, so long as the concrete placement temperature is properly controlled. The key technical issues have been solved in the design of Longtan Dam. Nevertheless, some issues would still need to be studied during its construction period.