资源描述：
《港航专业英语》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。
1、上WW事大学IIShanghaiMaritimeUniversity课程xxxx班级xxxx指导教师xxxxxxxxxxxx四年六月HydraulicEngineeringDamsAmongmankind'soldestworksareirrigationandwatersupplysystems;indeed,theearliestcivilizationsinrivervalleysintheMiddleEastwerebasedonagriculturethatdependedonirrigation.Harborfacilit
2、iesandcanalsfornavigationwerealsoearlyengineeringaccomplishments.Suchsystemsareusuallygroupedtogetherashydraulicengineeringprojects.Hydraulicsisthesciencethatdealswiththeflowandcontrolofwaterandotherfluids.Amongthemostimpressivemodernworksinhydraulicengineeringaresuchgr
3、eatdamsastheAswanHighDamontheNileinEgyptandtheHooverDamontheColoradoRiverintheSouthwesternUnitedStates.Thesedams,likemostmoderndams,serveanumberofdifferentpurposes.Amongthemarefloodcontrol,waterstorage,irrigation,navigation,andhydroelectricpower.Inaddition,mostdamsareal
4、solinksinahighwaysystem,witharoadwayrunningacrossthem.Thelakesbehindthem,likeLakeMeadwhichisbackedupbytheHooverDam,alsoserveasrecreationalareas・Beforedesignandconstructionofadamcanbegin,anextensivesurveyandstudyofthesitemustbemade・Thissurveyexaminesnotonlytopographicalf
5、eaturesofthearea,butalsosoilandrocksamplestodeterminethegeologicalfactorsthatmayaffectit.Thehydraulicfeaturesofthestreamorriverthatisbeingdammedmustalsobedeterminedtherateofvolumeofflowoftheriveratdifferentseasons,andthevolumeofwaterthatwillbebackedupbythedam.Engineersu
6、sethisinformationtocalculatepotentialwaterpressure.Itisalsonecessarytostudythesitetoseewhetherthedamcanbeconstructedwiththeuseofcofferdamsorwhethertheflowoftherivermustbediverted.Cofferdams,arewatertightpilesthatformanenclosurefromwhichwatercanbepumped・Whenitisnecessary
7、todiverttheriver,onetechniqueistodigtunnelsforthechannel;anotheristoexcavateatemporarychannelfortheriveraroundthedamsite.Evenafterthesitehasbeenthoroughlyinvestigatedandthedesignshavebeenmade,preliminaryworkisstillnotcomplete.Scalemodelsofthedamareoftenmadesothattheycan
8、betestedundersimulatedconditions.Computersarealsousedextensivelytocalculateallthedifferentstressestowhichsuchh
