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ID:36761759
大小:213.31 KB
页数:18页
时间:2019-05-14
《LEVELINGCaltransLEVELNG加州运输局》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、UNIT6LEVELINGBillJackson,PLSCarrolLeong,PLSCaliforniaDepartmentofWaterResourcesIntroduction“Leveling”isageneraltermusedinlandsurveyingthatappliestoverticalmeasurements.Verticalmeasurementsaremadeandreferencedtodatums,aselevations.Thereferencedatummightbeanarbi
2、traryelevationchosenforconvenienceoraveryprecisevaluedeterminedafterlengthystudies.ThestandardreferencedatumusedthroughoutCaliforniaismeansealevel,basedontheNationalGeodeticVerticalDatum(NGVD1929).Threemethodsusedtomeasuredifferencesinelevationaredirectvertica
3、lmeasurement,trigonometricleveling,anddifferentialleveling.Itisimportanttounderstandtheprocedure,equipmentandnotekeepingformatusedforeachmethod.CaltransLS/LSITVideoExamPreparationCoursePerformanceExpectedontheExamsDefinetheterms“curvature”and“refraction,”beabl
4、etocalculatetheircombinedeffectsandexplaintheprocedureusedtolimittheireffects.Explainhowtopegalevelandcalculatethecollimationcorrectionofaproperlyadjustedlevel.Givenfieldmeasurements,calculatethedifferenceinelevationbetweentwostationsusingtrigonometricleveling
5、method.Explain,interpret,reduceandadjustdifferentiallevelingnotes.Explain,interpret,reduceandadjustthree-wirelevelingnotes.Obtainthedifferenceinelevationbetweentwostationsbyreciprocalleveling.PlanandanalyzetheresultsofalevelingprojectwithregardtoNGSstandardsan
6、dspecifications.KeyTermsAltimetryLenkerrodAutomaticpendulumlevelMeansealevelBacksight(+shot)NationalGeodeticVerticaldatum(NGVD1929)BenchmarkNorthAmericanVerticalDatumCurvature(NAVD1988)DatumPeggingalevelDirectlevelingPhiladelphiarodDifferentiallevelingPlumblin
7、eElevationProfilelevelingForesight(-shot)ReciprocallevelingH.I.RefractionHorizontallineThree-wirelevelingHorizontalplaneTrigonometriclevelingIntermediateforesight(sideshot)Turningpoint(TP)LevelingVerticaldifferenceLevelsurfaceVerticallineLevelline6-2LevelingVi
8、deoPresentationOutlineBasicConceptsEarth'sSurface90˚1HorizontalLineElevationBenchmarkLevelLines2ElevationDatumVerticalLinesFigure6-1.Levelingconcepts.•Levelline•Horizontalline•Vert
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