从水库垮坝数量看我国的防洪标准

Viewing China Flood Control Standard Based on Quantity of Dam-Failure

1981年我国已建水库总数为86 881座,其中小型水库有81 215座;2006年为85 849座,其中小型水库有82 367座。在1954~2006年的52年间,共垮坝3 496座,其中属于洪水漫坝而垮者为1 800座,占垮坝总数的51.49%。但是,真正属于洪水超标准而垮者只有316座,其中大（2）型2座、中型水库17座、小型水库297座。采用超越概率和工程有效服务年数两种方法计算分析,结果表明：8万座小型水库在40~50年内因洪水超标准而垮坝的有297座,其相应的防洪标准为10 000~13 000年一遇。究其原因,一是在设计洪水计算过程中基于安全的考虑,层层加码,使计算结果严重偏大;二是在水工设计上,对大坝都设定了一定的安全超高等。

In 1981,the total existed reservoirs in China is 86 881,of which,small and medium sized ones 81 215.In 2006,the total number is 85 849,of which,small and medium sized ones 82 367.During 52-year period from 1954 to 2006,there are all together 3496 dam failures,of which,1 800 dam breaks because of flood overtopping,making up 51.49% of the total.While only 316 dams,including 2 large ones,17 medium sized and 297 small sized ones burst because of over standard floods.The paper calculates and analyzes the issue by using two methods of transcendental probability and the effective service life of project.The outcomes show that there are 297 small sized dams failure because of over standard floods among 80 000 ones during 40-50 years and the relevant flood frequency has reached to ones happened in 10 000-13 000 years.The reasons are as follows: a) during the calculation of design flood,it is getting greater and greater for safety purposes and finally the results of calculation become much greater and;b) on hydraulic design,the dam all has a certain limit of freeboard.