针对深厚覆盖层与围堰水下抛填施工密度确定和粗粒料工程特性试验中的缩尺效应问题，国家十一五科技支撑计划课题“深厚覆盖层条件导截流及围堰安全控制技术”中的专题 3 以乌东德、白鹤滩和双江口等水电站围堰工程为依托，采用现场测试、室内试验、物理模型、数值计算等多种研究手段，进行了深厚覆盖层及堰体材料工程特性试验技术研究。概要地介绍了该专题的主要研究内容和技术路线以及取得的主要成果，详细研究方法和具体成果将另文介绍。

River diversion and closure and technology of cofferdam safety control with thick overburden is studied in a research project supported by the National Key Technology R&D program. In special topic 3 of the project, field test, laboratory test, physical modeling and numerical calculation are employed to investigate the engineering properties of thick overburden and cofferdam materials in the purpose of tackling the scale effect in engineering property tests on coarse  grained materials and determining the underwater dumping  filling density for the cofferdam with thick overburden. Wudongde, Baihetan and Shuangjiangkou Hydroelectric Station cofferdam projects are taken as background and case study for the special topic. The main content, technical route and important achievements of the topic are briefly presented. Detailed research approaches and achievements will be reported later.