水利水電專(zhuān)業(yè)文獻(xiàn)翻譯中英文對(duì)照-wenkub
2022-12-16 22:12:26 本頁(yè)面
【正文】 力 U為： U=r(h1+h2)t/2 (2) 式中： t是壩基的寬度， h1和 h2分別是壩踵和壩址處的水深。壩踵附近通常設(shè)有排水裝置，以便排除滲 流水量，以減小揚(yáng)壓力。 一些壩的實(shí)測(cè)資料表明，揚(yáng)壓力比公式（ 2）所給出的值小的多。 處于壓力作用下的水必然要在壩和壩基之間流動(dòng)，因而產(chǎn)生 了揚(yáng)壓力，揚(yáng)壓力的大小取決于基礎(chǔ)的特性和施工方法。靜水壓力可同時(shí)作用在壩的上游面和下游面。這些力 傳給壩基和壩座，而壩基和壩座則對(duì) 壩體產(chǎn)生一個(gè)大小相等方向相反的基礎(chǔ)反力。 壩高定義為路面或溢洪道頂與基坑最低點(diǎn)之間的高程差。工程可行性受地形 ﹑ 地質(zhì)及氣候條件所支配。在一座大壩的結(jié)構(gòu)中可包含不止一種壩型。拱壩通過(guò)拱的作用把水的水平推力中的大部分傳給拱座，因此，他的橫截面比重力壩單薄些。在 1976年 6 月愛(ài)達(dá)荷州泰托大壩失事后，美國(guó)對(duì)大壩安全更為關(guān)注。大壩失事可能造成生命財(cái)產(chǎn)的嚴(yán)重?fù)p失。它使尼羅河改道，并為古老的孟菲斯提供城址。 consequently, the design and maintenance of dams are monly under government surveillance. In the United States over 30,000 dams are under the control of state authorities. The 1972 Federal Dams Safety Act (PL92367)requires periodic inspections of dams by qualified experts. The failure of the Teton Dam in Idaho in June 1976 added to the concern for dam safety in the United States. 1 Type of Dams Dams are classified on the type and materials of construction, as gravity, arch, buttress ,and earth .The first three types are usually constructed of concrete. A gravity dam depends on its own weight for stability and it usually straight in plan although sometimes slightly curved. Arch dams transmit most of the horizontal thrust of the water behind them to the abutments by arch action and have thinner cross sections than parable gravity dams. Arch dams can be used only in narrow canyons where the walls are capable of withstanding the thrust produced by the arch a
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