专业外语-水工部分

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1、Lesson11dams坝ThefirstdamforwhichtherearereliablerecordswasbuiltontheNileRiversometimebefore4000B.C.itisusedtodiverttheNileandprovideasitefortheancientcityofMemphis.据可靠记载，世界上笫一朋坝是公元前4000年以前在尼罗河上修建的。他使尼罗河改道，并为古老的孟菲斯城提供城址。TheoldestdamstillinuseistheAlmanzaDaminSpai

2、n,whichwasconstructedinthesixteenthcentury・Withthepassageoftime,materialsandmethodsofconstructionhaveimproved,makingpossibletheerectionofsuchlargedamsastheNurekDamwhichisbeingconstructedintheFormerSovietUnionontheVakshRiverneartheborderofAfghanistan.Thisdamwillb

3、e1017ft(333m)high,ofearthandrockfill.至今仍在使用的最古老的坝是16世纪修建的西班牙阿尔曼扎坝。随着岁月的流逝，各种建筑材料和施工方法得到了改善，修建列努克这样的大坝才成为可能。该坝正在前苏联境内靠近阿富汗边界的瓦赫什河上施工，是一座高达1017英尺(333米)的土石坝。Thefailureofadammaycauseseriouslossoflifeandproperty;consequently,thedesignandmaintenanceofdamsarecommonlyun

4、dergovernmentsurveillanee.IntheUnitedStatesover30,000damsareunderthecontrolofstateauthorities.The1972FederalDamSafetyAct(PL92-267)requiresperiodicinspectionsofdamsbyqualifiedexperts・ThefailureoftheTetonDaminIdahoinJune1976addedtotheconcernfordamsafetyintheUnited

5、States.大坝失事可能造成牛命财产的严重损失。因此，坝的设计和维修通常是在政府监督下进行的。美国有3万多屎坝由各州政府控制着。1972年(美国)联邦人坝安全法(PL92-367)规定，必须由合格的专家对大坝进行定期检查。在1976年6刀爱达荷州提堂人坝失事后，美国对人坝安全更为关切。1typesofdams坝的类型Damsareclassifiedonthebasisofthetypeandmaterialsofconstruction，asgravity,arch,buttress,andearth・Thefir

6、stthreetypesareusuallyconstructedofconcrete.Agravitydamdependsonitsownweightforstabilityandisusuallystraightinplanalthoughsometimesslightlycurved・Archdamstransmitmostofthehorizontalthrustofthewaterbehindthemtotheabutmentsbyarchactionandhavethinnercrosssectiontha

7、ncomparablegravitydams・Archdamscanbeusedonlyinnarrowcanyonswherethewallsarecapableofwithstandingthethrustproducedbythearchaction.Thesimplestofthemanytypesofthebuttressdamsistheslabtype,whichconsistsofslopingflatslabssupportedatintervalsbybuttress・Earthdamsareemb

8、ankmentsofrockorearthwithprovisionforcontrollingseepagebymeansofanimpermeablecoreorupstreamblanket.Morethanonetypeofdammaybeineludedinasinglestructure.Curveddamsmayco