中文摘要：

水电工程中高度200 m及以上的特高坝的设计已经超出现行规范的适用范围;考虑流域梯级效应的水库群的安全标准,迄今尚属空白。本文从公共安全风险防范和梯级连溃系统风险分析的角度,在现行水利水电枢纽工程等级划分及其设计安全标准的基础上,针对特高坝及其对下游梯级具有溃坝影响的大坝,提出了设立特等工程、特级建筑物及其相应安全标准的建议。经初步论证,建议特2级土石坝年计失效概率为5×10-8,目标可靠指标为4.45,坝坡抗滑稳定安全系数为1.6;特1级土石坝年计失效概率为1×10-8,目标可靠指标为4.7,坝坡抗滑稳定安全系数为1.7。基于我国某流域实际情况的一个虚拟大坝连溃案例,验证了确定上述工程等级和安全标准的可行性,对我国现有水电工程设计规范的修正和完善具有一定的参考意义。

英文摘要：

The rapid development of China＇s hydropower projects has resulted in a number of large dams whose heights exceed 200 m, an applicability limit of various design codes. Another concern comes from the cascade hydropower devolvement on a river, in which break of one dam may cause serious downstream secondary disasterds. Based on a comprehensive review on the social and professional safety control stan- dards the authors propose in these paper two extra classes as well as their related design criteria to the ex- isting Chinese dam classification systems. Class E2 refers to a dam with a height ranged between 200-250 m, or a dam whose breaching would cause a secondary break of a downstream Class 1 dam if early warn- ing is not available. The allowableannual probability of failure, reliability index and slope safety factor are specified as 5~10s, 4.45, and 1.6 respectively. Class E2 refers to a dam with a height ranged between 250-300 m, or a dam whose breaching would cause a secondary break of a downstream Class 1 dam even with early warning. The allowable annual probability of failure, reliability index and slope safety factor are specified as 10s, 4.7, and 1.7 respectively. An in-depth study on risks and standards associated with these dams has been provided to assess the applicability of the proposed criteria which can be useful for the work of code revision.