Inclinometer by milan kumar rai

Inclinometer

1. INCLINOMETERS
Presented By:
Name:MilanKumarRai
Roll No.: 17

2. CONTENTS
INTRODUCTION, INCLINOMETER CONFIGURATION, INSTALLING
(CASING)ANDMONITORING, INCLINOMETER MEASUREMENT
SYSTEM,OPERATION,IMPORTANCE OFSLOPEINCLINOMETER
DATA,PROPER INSTALLATION AND MONITORING OF
INCLINOMETER,ERRORS

3. INTRODUCTION
Aninclinometerisaninstrumentformeasuringangles
ofslope,elevationordepressionofanobjectwith
respecttogravity.
Slopeinclinometers/indicatorsareusedtodetermine
themagnitude,rate,direction,depthandtypeof
landslidemovement.Italsomonitorstheonsetand
continuationofdeformationnormaltotheaxisofthe
boreholecasingbypassingaprobealongthecasing.
Theyfallintotwocategories:probeinclinometersand
fixed-in-placeinclinometers.Mostlyprobeisused.
Probeinclinometerisbothuniaxialandbiaxial.

4. INCLINOMETER CONFIGURATION
Fig 1 a: Inclinometer ConfigurationFig 1 b: Inclinometer Operation

5. INCLINOMETER
CONFIGURATION (contd…)
Theinclinometerprobeisconnectedtoapowersourceand
readoutunittoenablemeasurements.
Theelectricalcablelinkingtheprobetothereadoutdevice
isusuallymarkedin0.3or0.6-mincrementssotheshapeof
thecasingcanbemeasuredatconsistentdepthsor
locations.
Themeasurementsaretakenstartingatthebottomofthe
inclinometer.Subsequentreadingsaremadeofthecasingas
theprobeisraisedincrementally,usuallyin0.3or0.6-m
intervals,tothetopofthecasing.Thisprocessisconducted
shortlyafterthecasingisinstalledtodeterminetheinitial
shapeofthecasing,i.e.,obtainthezeroreading.

6. INSTALLING & MONITORING
Thebottomoftheinclinometermustbelocatedwell
belowthepotentialzoneofmovementsothebottom
oftheinclinometerdoesnottranslateandalsothe
inclinometerwillnotcapturethetotalamountof
movement.
Thesameprobeandelectricalcableusedforthezero
readingshouldbeusedforsubsequentreadingssoall
ofthereadingsarecomparabletothezeroreading.
Allofthereadingsshouldbeperformedbythesame
person.

7. INSTALLING &
MONITORING (contd…)
Thesameelectricalcableshouldbeusedsothatthe
probereadingsaretakenatthesamedepthasthezero
readingsothedeflectionisdeterminedatthesame
depth.
Ifdifferentprobesareused,thesensorscan/willhave
differentsensitivities,zerovoltages,andcalibration
factorsthatcanresultintheappearanceofadifferent
inclinationorshapeofthecasing.

8. Operation
Thein-placeinclinometersystemconsistsofinclinometercasing
andachainofinclinometersensors.Theinclinometercasing,
whichcontrolstheorientationofthesensors,isinstalledina
trenchorhorizontalboreholewithonesetofgroovesoriented
vertically.Thesensorsarethenpositionedwithinthecasing.
Thesensorsmeasuretheinclinationofthecasing(tiltfrom
horizontal).Changesintheinclinationreadingsindicatethatthe
casinghasbeendisplacedbygroundmovement.Theamountof
displacementiscalculatedbyfindingthedifferencebetweenthe
currentinclinationreadingandtheinitialreadingandthen
convertingtheresulttoaverticaldistance.

9. IMPORTANCE OF SLOPE
INCLINOMETER DATA
MagnitudeAndLocationOfMovement
Theprobemeasuresthetiltofthecasingwhichcanbe
convertedtoahorizontalmovement.Thedeviationfrom
verticalisdeterminedbythesinefunctionandexpressedas:
Deviation from vertical = L x sinθ
where,θistheangleoftiltandListhedistancebetweenthe
probewheelcarriages.Thedeviationvaluescanbeplottedas
slopechangevs.depthtoshowmovementateach
measurementinterval.Thetotalhorizontaldisplacementis
achievedbysummingtheindividuallateraldeviationsfrom
thebottomofthecasingtothetop.

10. IMPORTANCE OF SLOPE
INCLINOMETER DATA (contd…)
Fig 3: Graph of displacement vs. time.Fig 4: Magnitude and direction of
movement using A-and B-axes.

11. IMPORTANCE OF SLOPE
INCLINOMETER DATA ( contd…)
RateofMovement
Itdetermineswhetherornottheslideisaccelerating,
decelerating,orcontinuingatthesamerate.
Iftheslideisslowing,evacuationmaynotbe
necessaryandremedialmeasuresmaybepossible.
Therateofmovementisalsoofimportanceto
investigatetheeffectofrainfall,slopeloading,toe
excavation,andremedialmeasuresonslopestability.

12. IMPORTANCE OF SLOPE
INCLINOMETER DATA ( contd…)
DirectionofMovement
Knowingthedirectionofmovementcanreducethe
numberofcross-sectionsthatneedtobeconsideredin
thestabilityanalysesandremedialdesign.
Thedirectionofmovementcanalsobeusedto
determineiftheslideismovingasasingleunitornot,
whichcanfacilitatedeterminingcausationand
remediation.

13. PROPER INSTALLATION
& MONITORING
CasingInstallation
Theinclinometercasingbeinstalledasstraightand
verticalaspossible.Errorsininclinometer
measurementsareproportionaltotheproductof
casinginclinationandangularchangesinsensor
alignment.
Adepthofabout6mormorebelowtheelevationof
theexpectedactivezoneofmovementissuggested.
Theinclinometercasingshouldbeflexibleenough
tomovewiththesoilwhenthesoildeforms
laterally.

14. PROPER INSTALLATION
& MONITORING (contd…)
InclinometerMonitoring
Thezeroorinitialmeasurementoftheoriginal
profileshouldbeestablishedbyatleasttwosetsof
readings.Ifanysetofreadingsdeviatefromthe
other,thesereadingshouldberechecked.
Inclinometermeasurementsgenerallyarerecordedas
thealgebraicsumsordifferencesofthepairof
readingsinthetwo-passsurvey.Computingthe
algebraicdifferenceofthereadingsforeachdepth
eliminateserrorsresultingfromirregularitiesinthe
casingandinstrumentcalibration.

15. PROPER INSTALLATION
& MONITORING (contd…)
InclinometerAccuracy
Theprecisionofinclinometermeasurements
dependsonseveralfactorssuchasthedesignofthe
sensorandqualityofthecasing,probe,cable,and
readoutsystem.
Bias-shifterror
Thesensorbiasisthereadingoftheprobewhenit
isvertical.Initially,thesensorbiasissetcloseto
zerointhefactory,butitmaychangeduringfield
use.,themagnitudeofthebiasshiftcanbe
evaluatedusingthechecksum,whichshouldbe
zeroifthereisnobiasshift.

16. ERRORS
RandomerrosversusSystematicerrors
Mikkelsen(2003)indicatesthatarandomerroris
typicallynomorethan±0.16mmforasingle
readingintervalandaccumulatesatarateequalto
thesquarerootofthenumberofreadingintervals
overtheentirecasing.Ontheotherhand,the
systematicerrorisabout0.13mmperreading
undercontrolledlaboratoryconditions,andit
accumulatesarithmetically
Thesystematicerrorsmaymaskshearmovements
occurringatslipsurfacesandthusshouldbe
evaluatedandcorrectedduringdataprocessing.

17. SYSTEMATIC ERROS
Themaintypesofsystematicerrorsarebias-shift
error,sensitivitydrift,rotationerror,anddepth
positioningerror.
Bias-shifterrorisrelatedtoasmallchangeinthebias
oftheinclinometerprobeovertime.Thebias-shift
erroristhemostcommonsystematicerror&result
fromslightjarringoftheprobeduetoroughhandling
bytheoperator.
Thesensitivitydriftisdirectlyproportionaltothe
magnitudeofthereadings,anditvariesbetweendata
setsbutisrelativelyconstantforeachdataset.
Therotationerroroccurswhentheinclinometercasing
deviatessignificantlyfromvertical.

18. Thank You!
for your Kind Attention.