黄土高原坝系工程的相对稳定性

Relative stability dam system in Loess Plateau

坝系要达到相对稳定,最基本的条件有3个:一是相对稳定系数必须大于或等于一定的允许值,这是坝系要达到相对稳定的关键;二是有足够的防洪能力;三是坝系工程安全无病险。同时也应该满足以下条件:20年一遇的暴雨洪水标准下坝地作物可以保收;当淤地面积达到设计的可淤面积时,坝地平均淤积厚度<20cm。其控制方法主要是:合理布设坝系规模与建坝顺序;实现对暴雨洪水的均衡分配;坚持坡面治理,提高流域治理度;布设排洪渠,以防坝地积水及超标洪水;加强日常养护。

The basic conditions, which the dam system can come up to relative stability, are as follow. First, the coefficient of relative stability must be equal or larger than a certain permissible value, which is the key to achieve the goal. Then there must be enough storage capacity of flood control, and last the dam system must be safe without disease and danger. In the same time it should be satisfied with these conditions. The harvest in the dam land can be ensured under the standard of storm flood once in twenty years. When the silt area has come up to design silt area, the average silt thickness will be smaller than 20 cm. The control methods of stability are rational arrangement of dam system scale and the order of construction, balanced distribution of storm flood persisting in slope control, raising the degree of watershed control, fixing up the flood carrying channels to prevent water logging at the dam land and flood exceeding the standard, as well as enhancing routine maintenance.