外文翻译跨越式精确三角高程测量.docx
- 文档编号:12017285
- 上传时间:2023-04-16
- 格式:DOCX
- 页数:21
- 大小:269.81KB
外文翻译跨越式精确三角高程测量.docx
《外文翻译跨越式精确三角高程测量.docx》由会员分享,可在线阅读,更多相关《外文翻译跨越式精确三角高程测量.docx(21页珍藏版)》请在冰豆网上搜索。
外文翻译跨越式精确三角高程测量
附录A外文翻译
PreciseHeightDeterminationUsingLeap-Frog
TrigonometricLeveling
AyhanCeylan1andOrhanBaykal2
Abstract:
Preciselevelinghasbeenusedforthedeterminationofaccurateheightsformanyyears.Theapplicationofthistechniqueisdifficult,timeconsuming,andexpensive,especiallyinroughterrain.Thesedifficultieshaveforcedresearcherstoexaminealternativemethodsofheightdetermination.Asaresultofmodernhigh-techinstrumentdevelopments,researchhasagainbeenfocusedonprecisiontrigonometricleveling.Inthisstudy,aleap-frogtrigonometricleveling(LFTL)isappliedwithdifferentsightdistancesonasampletestnetworkattheSelcukUniversityCampusinKonya,Turkey,inordertodeterminetheoptimumsightdistances.Theresultswerecomparedwithprecisegeometriclevelingintermsofprecision,cost,andfeasibility.Leap-frogtrigonometriclevelingforthesightdistanceS=150mresultedinastandarddeviationof±1.87mm/
andwithaproductionspeedof5.6km/day.
CEDatabasesubjectheadings:
Leveling;Height;Surveys.
Introduction
Thedevelopmentoftotalstationshasledtoaninvestigationofprecisetrigonometriclevelingasanalternatetechniquetoconventionalgeometricleveling(Kratzsch1978;RuegerandBrunner1981,1982;KuntzandSchmitt1986;Hirschetal.1990;Whalen1984;Chrzanowskietal.1985;KellieandYoung1987;Youngetal.1987;Haojian1990;Aksoyetal.1993).Mostofthesepapersgivemorepracticalresults,ratherthantheoretical.
Inthisstudy,wetreatthesubjectmoretheoretically,withcurrentinstruments.Wealsodiscusstheoreticalaspectssuchaslimitsofthetechniques,errors,andaccuraciesinleap-frogtrigonometricleveling.
Slopedistancesandzenithanglesaremeasuredusingeitheraunidirectionalorareciprocalorleap-frogmethodoffieldoperationintrigonometricleveling.Bothofthetargetsinleap-frogtrigonometriclevelingcanalwaysbeplacedatthesameheightabovetheground.Thus,sightlengthsarenotlimitedbytheinclinationoftheterrain,andsystematicrefractionerrorsareexpectedtobecomerandombecausetheback-andforesightlinespassthroughthesameorsimilarlayersofair.Thenumberofsetupsperkilometercanbeminimizedbyextendingthesight
lengthstoafewhundredmeters.Thisreducestheaccumulationoferrorsduetoinstrumentsettlementthatisanothersignificantsourceofsystematicerror.
1AssistantProfessor,EngineeringandArchitectureFaculty,KonyaSelcukUniv.,42031Konya,Turkey.E-mail:
aceylan@selcuk.edu.tr
2Professor,CivilEngineeringFaculty,IstanbulTechnicalUniv.,80626Istanbul,Turkey.
Note.DiscussionopenuntilJanuary1,2007.Separatediscussionsmustbesubmittedforindividualpapers.Toextendtheclosingdatebyonemonth,awrittenrequestmustbefiledwiththeASCEManagingEditor.Themanuscriptforthispaperwassubmittedforreviewandpossible
publicationonAugust6,2003;approvedonAugust25,2005.
PrincipleofUnidirectionalTrigonometricLeveling
Trigonometriclevelingisthedeterminationofheightdifferencesbymeansofthemeasuredzenithanglesandtheslopedistance.Similartogeometricleveling,theheightdifferencebetweentwoturningpoints(benchmarks)iscomputedasthesumofseveralsingleheightdifferencesobtainedfromeachsettlement.
Themeasurementmodeloftheunidirectionaltrigonometricleveling(UDTL)isillustratedinFig.1.Thetotalstationissetupatonlyonepointandtheobservationsareperformedonlyinonedirection.
InFig.1,
=geodetic(ellipsoidal)zenithanglefrom
to
;
=observedzenithanglefrom
to
;
=modelerrorduetotherefractioneffect;Ƹij=modelerrorduetothedeviationoftheplumbline;Sij=slopedistancebetweenPiandPj;hiandhj=ellipsoidalheightsofPiandPj,respectively;Rm=meanradiusoftheearth(≈6,370km)and∆hij=heightdifferencefromPitoPj.
Theheightdifference∆hijisformulatedas
(1)
wherethefirsttermisthenominalheightdifference,thesecondtermisthesphericaleffectoftheearth,andthethirdtermisthetotaleffectduetothedeviationoftheplumblineandtheverticalrefraction(CoskunandBaykal2002).
Thecoefficientofrefraction,kij,isdefinedastheratiobetweentherefractionangledZriandhalfofthecenterangle
(RuegerandBrunner1982);i.e.
(2)
and
(3)
Thecenterangle,
canbecomputedas
(4)
If
isintroducedintoEq.(3),themodelerrorduetotherefractioneffect,dZri
isobtainedasfollows:
(5)
TheheightdifferencebetweenthestationpointsPiandPjviaunidirectionalzenithangleobservationisobtainedfromEqs.
(1)and(5)
(6)
Inpractice,theeffectofdeviationofplumblineisverysmallbecausethezenithanglesobservedalongthesightlengthsarenotlongerthan500m.Thus,thesecondterminEq.(6)canbeignored(RuegerandBrunner1982).Asaresult,theheightdifferencebetweenthestationpoints,PiandPj,iscomputedfromUDTLobservationsas
PrincipleofLeap-FrogTrigonometricLeveling
Observationofleap-frogtrigonometricleveling(LFTL)wasperformedinbackandforesightreadingatonesetupofthetotalstationbetweentwoturningpoints,thesamemethodusedingeometricleveling.ThemeasurementmodeloftheLFTLisshowninFig.2.
Fig.2.MeasurementmodelofLFTL
AccordingtoFig.2andEq.(7),theheightdifferencebetweenthestationpoints,PiandPj,isobtainedfromLFTLobservationsas
Considering
wherethefirsttermisthenominalheightdifference,thesecondtermisthesphericaleffectoftheearth,thethirdtermistheeffectduetotheverticalrefraction,andthefourthtermisthetotalinfluenceofallotherrandomerrors,namely,sinkingoftargetrods,verticalityandcalibrationofrods,anduncertaintiesinthedeviationsofplumblines.Ifweusethefollowingassumptions:
thesecondterminEq.(9)willbezero.Asaresult,theheightdifferencebetweenthestationpoints,PiandPj,iscomputedas
ItisobviousthattheheightdifferenceobtainedfromEq.(11)isaffectedbythedifferenceintheactualrefractioncoefficientsandotherrandomerrorsintheleap-frogtrigonometricleveling(LFTL).Therefractiontermrequiresfurtherinvestigation.TheuncertaintyintherefractiontermofEq.(11)canbeminimizedbymakingthelengthsoftheback-andforesightsequal.However,inequalitiesoftenexistbetweentherefractioncoefficientsofthebacksightandforesight,evenifthesedistancesareequal.Inanycase,themethodofLFTLwillmakethedifferenceinthecoefficientsofrefractiontolerablysmall.Foraspecialcase,themeancoefficientofrefractionkofalengthcanbecomputedfromreciprocalzenithangleobservations
TheaccuracyofLFTLcanbeobtainedbyapplyingthelawofvariancepropagationtoEq.(11)underthefollowingassumptions:
Afterpropagatingerrors,anexpressionforthevarianceinheightdifferencebetweenPiandPjcanbederivedas
Standarddeviationsofthedistances,thezenithangles,therefractioncoefficients,andotherrandomerrorsaredenotedby
respectively.Thevarianceofa1kmlevellineiscomputedas
Thecomputedstandarddeviationsofa1kmLFTLline,basedonstandarddeviationsof±1.0″,±2.0″,and±3.5mmforzenithanglesandslopedistances,respectively,aresummarizedinTable
1.Theuncertaintyinthecoefficientofrefractionistakenas±0.05and±0.10for(nonsimultaneous)reciprocalzenithangleobservations.Thevalueof
hasbeenarbitrarilyacceptedas±0.30mmfortotalinfluenceofallotherrandomerrors.
Table1.StandardDeviations_inmm_ofa1kmLFTLLinewithSightDistancesof100,150,200,and300mandAverageZenithAnglesof80,85,and90°
Applications
Thepreciseleveling(PL)andLFTLmeasurementswereperformedonalevelingnetworkwitheightpointsestablishedonhillyterrainattheCampusAreaofSelcukUniversityinKonya,Turkey(Fig.3).
DesignandCalibrationofSurveyingInstruments
PLmeasurementswerecarriedoutbyameasurementteamofsixpeople(oneobserver,onerecorder,tworodmen,andtwoauxiliary)usingapreciselevelinginstrument(WildN3)equipped
withaparallelglassmicrometerandapairof3minvarrods(Wild).
LFTLmeasurementswereperformedbyateamoffourpeopleusingapairoftargetrodsandatotalstation.Theaccuracyofzenithanglemeasurementwithsixseriesis±1″usingthetotalstationSokkiaSET2[telescopemagnification:
30x;minimumreading:
1″;accuracyofhorizontalandzenithanglemeasurement:
±2″;accuracyofdistancemeasurement:
±(3mm+2ppm·S)].Targetrodswereformedbytwoparts,abottomone,whichwasaninvarrodof2m,andatopone,whichwasanironbar1minlengthand2cmindiameter.Thesetwopartswereattachedtogether.Areflectorwasmountedontargetrodataheightof1.70mfromthebottominordertoimplementdistancemeasurementsandtwotargetplatesforverticalangleobservationsatlevelsof2.20and3.00m,respectively.Acircularspiritbubble(with10′precision)andatripodwereusedtoplumbthetargetrod(Fig.4).
Severaltargetplateswithdifferentpatternsofvariousdimensionswereinvestigatedfortargetingaccuracyofsightdistancesof200and300m.AredandwhitecoloredcircletargetwaspreferredforLFTL.Ithasbeenproventhattheaccuracyofsingletargetingisbetterthan30″/M(M=telescopemagnification)inaverageatmosphericconditions(Chrzanowski1989).Consequently,thetargetplateinFig.5ispreferred.
BecauseapairoftargetrodsisusedcommonlyinLFTL,theheightdifferencesbetweenthetargetplatesonbackwardandforwardrodsshouldbedeterminedwiththehighes
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 外文 翻译 跨越 精确 三角 高程 测量