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HealthandSafetyExecutive
Guidanceontheuseofrockboltstosupportroadways incoalmines
Thisguidanceonthesupportofmineroadwaysincoalminesbyrockbolts wasprepared,inconsultationwiththeHealthandSafetyExecutive(HSE), bytheDeepCoalMinesIndustryAdvisoryCommitteewhichwas appointedbytheHealthandSafetyCommissionaspartofitsformal advisorystructures.Theguidancerepresentswhatisconsideredtobe goodpracticebymembersoftheCommittee.Ithasbeenagreedbythe Commission.
Undercurrentlegislationrockboltsmayonlybeusedastheprincipal supportofmineroadwaysincoalminesifHSEhasgrantedexemption fromtherequirementsofsection49(i)oftheMinesandQuarriesAct1954 andregulations13and14oftheCoalandOtherMines(Support) Regulations1966.Itwillbeaconditionofanysuchexemption,tocarryout therockboltingoperationsinaccordancewiththeguidance.
Thiswebonlyversionreplacesthe1996editionofthisguidance.
Introduction
1 Thisdocumentprovidesguidanceonthesafeuseofrockboltstosupport roadwaysincoalmines.Itisaimedatcoalminemanagers,supervisorsandmine workerswhohaveresponsibilityforrockboltsupportoperations.
2 Theguidanceappliestotheplacesincoalmineswhererockboltsprovidethe principalsupportandmayinclude:
developmentheadingsandjunctions; coalfacedevelopmentdrivages; retreatdistrictgateroadsincludingthefaceTeejunction; roomandpillarcoalproductiondistricts; specialpurposedrivages,egtohouseequipment.
3 Examplesofplaceswhichmaynotbesuitableare:
goafscours; gateroadsservingadvancingfaces; crossmeasuresdrifts; headingsformedbyshotfiringoffthesolid.
4 Roadwaysimmediatelynexttogoafsarenotsuitableforsupportbyrockbolts andarenotcoveredbythisguidance.
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Definitions
5 Thefollowingdefinitionsapplythroughoutthisguidance:
Freestandingsupports aresupportswhichareerectedbetweenthefloor androof,egarches,girders,hydraulicpoweredsupports,chocks/cribs,props andbars.
Inspectionofficials areappointedtocarryoutinspectionsunderregulation 12oftheManagementandAdministrationofSafetyandHealthatMines Regulations1993(MASHAM).
Membersofthemanagementstructure aretheminemanagerandother peopleappointedtotheminemanagementstructureunderregulation10of MASHAM.
Principalsupportiswhererockboltsprovidethesupportevenwheretheyare usedinconjunctionwithsupplementarysupport.
Rockbolt isabarinsertedintotherooforsideofaroadwaywhichisusedin conjunctionwithfullyencapsulatingresinorsomeotherappropriatesubstance toprovidereinforcementoftheroofandsidesofaroadwayorworkingplacein a mine.
Rockboltedheading/roadway isaheading/roadwayinwhichrockbolts providethemainmeansofsupport.
Geotechnicalassessmentandsiteinvestigation
6 A geotechnicalassessmentandsiteinvestigationarefundamentalprerequisites forthedesignofasupportsystem.Theresultsneedtoberecorded.
7 Themanagershouldappointasuitablyqualifiedandcompetentpersonto undertakeandrecordtheresultsofageotechnicalassessmentandonthebasisof theassessmentdesignasafeandsuitablerockboltsystem.Asuitablequalification forsuchapersonwouldbeacharteredengineer,orequivalent,whohashadthree yearsappropriateexperienceinworkrelatedtominestratacontrol.Forthe purposesofthisbooklet,thispersonisreferredtoasthedesignengineer.
8 Theassessmentneedstotakeintoaccountallfactorslikelytoaffectthe performanceofthesupportsystemduringthelifeoftheroadway.Itshouldalso considerthestratadeformationprocessestobecontrolledandtheactionofthe boltingsystemincontrollingthedeformation.
9 Theareacoveredby theinvestigationneedstobedefinedandanysubsequent supportsystemdesignconfinedtothatarea(seeparagraph13).Theassessment needstoincorporateallrelevantfeaturesfromtheinitialdevelopmentand throughoutitsworkinglife.
10 Thesiteinvestigationneedstoincludereferencetothefollowing:
geology: includingthestratasection,rockproperties,faults,cleat,parting planes,presenceofwateroranysubstancelikelytoflow,boreholeinformation andgradients.Allfactorsneedtobecorrelatedrelativetothemininghorizon;
stress: thedirectionandmagnitudeofthestressfieldcomponentsforpremining,mininginducedconditionsandinteraction;
pillardesignandeffects: theassessmentneedstoincludedrawingsand diagramstoillustratepotentialriskareas;
environmentaleffects: theeffectsofambienttemperature,minewaterand associatedimpurities;
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bondstrength: measuredbyshortencapsulationpulltestsusingthe proposedrockboltingmaterialsandcomponents(seeAppendix1).Thetests needtobecarriedoutforallmajorroofhorizonchangeswithinthelengthof theproposedrockboltandtheeffectsofwetflushingoralternativedustcontrol systemonthebondstrengthdetermined.Thebondstrengthneedstohavea minimumvalueof130kNewtons,forabondlengthof0.3m,over50%ofthe boltlength;
standuptime: dilationrelatedtodistancefromtheface(seeAppendix9).
11 Theassessmentneedstobesignedbythepersonorpeoplecarryingoutthe investigation.
12 Ifrockboltingistobeconsideredelsewhereinthesameseam,sufficient investigationneedstobecarriedouttoconfirmthattheconditionsaresimilarto thoseatprevioussites.Ifconfirmed,theinformationestablishedatthosesitesmay beusedagainandreferencemadetotheearliersiteinvestigation.
13 Asupplementarysiteinvestigationshouldbecarriedoutwheneverthereisa majorchangeinthemethodofwork,lithology,structureorconditions.
Supportsystemdesign
14 Wherethesiteinvestigationandgeotechnicalassessmentindicatesthatthe strataissuitablefortheuseofrockboltsasthemainmeansofsupport,asupport designneedstobeprepared.Whereanexistingdesignhasalreadybeenproved, referencetoitmaybemadeforotherroadwaysofsimilardimensionsinthesame seam.Thisisprovidingthatsuitableandsufficientstepsaretakentoshowthatthe geologicalconditions,rockpropertiesandstressfieldsatbothsitesare substantiallysimilar.
15 Adesignengineerwillpreparetheinitialdesignoftherockboltingsystemon thebasisoftheresultsofthesiteinvestigation.Asaminimum,thedesignneedsto takeaccountofthefollowing:
theprofileoftheheading; thelengthofrockboltstobeusedintheroofandribs.(Therecommended
minimumlengthintheroofis1.8m); thedensityofrockboltsintheroof.(Therecommendedminimumdensityof
supportis1bolt/sqmbutsiteinvestigationmayindicateaneedforhigher densities);
theplacingofrockbolts.Itisrecommendedthatboltstobeusedintheroof areinstalledasclosetothefaceoftheheadingaspossibleandassoonas practicableafterexposureoftheroof;
thetypeofrockbolt.Allboltstobeusedintheroofshouldbefullcolumnresin bonded;
holesdrilledforroofholes.Theyneedtobeformedinsuchawaythatthe bondstrengthparametersareachievedandthefinishedholediameterdoes notexceedthenominalboltdiameterbymorethan7mm;
a systemofsupportfortheroadwaysides,wheretheinitialassessment demandstheprovisionofsuchsupport.
16 Whentheinitialdesignhasbeencompleted,documentationneedstobe prepareddetailingthe:
useoftheroadway/junction; freestandingsupplementarysupportifapplicable; layoutanddimensionsoftherockboltingpattern;
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specificationofrockboltingconsumablestobeused; methodofwork; maximumfacetoboltdistance;and designverificationmonitoringsystem.
17 Thedesigndocumentshouldbesignedbythedesignengineerandwillform thebasisofthemanagerssupportrules.
Designverificationmonitoring
18 Theinitialdesignofthesupportsystemneedstobeverifiedbycomprehensive monitoring.
19 Comprehensivemonitoringfordesignverificationinvolvesdetailed measurementofroofdilationandrockboltloads.Itmayalsoinvolvedetailed measurementofribdilationandroadwayinternalmeasurements.Measurementof roofdilationneedstobetoanaccuracyof1mmataminimumof15pointsovera heightofatleast7m.Rockboltloadsneedtobemeasuredonaminimumoffour rockboltsdistributedacrosstheroadwaysection.Detailsoftheinstrumentsused areinAppendix2and3.
20 Wherechangesareproposedinroadwaydimensionsormethodsofworking, orwheretheyareobservedtooccuringeotechnicalconditions,furtherdesign verificationmonitoringneedstobecarriedouttoassessthecontinuedvalidityof thedesign.
21 Aplanneedstobepreparedshowingdetailsofthesitingofmonitoringstations inrelationtogeologicalandminingfeaturesandincludedetailsofthe instrumentationateachstation.Eachmonitoringstationneedstobegivena uniqueidentificationcodewhichcanbeusedtoidentifyreadings.
22 Monitoringinstrumentsneedtobereadbysuitablytrained,competentand authorisedworkersusingappropriateequipment.
23 Themonitoringresultsandinterpretationneedtoberetainedforfuture reference.
24 Theresultsofthemonitoringneedtobeinterpretedbythedesignengineer. Anyactionsorchangesrecommendedneedtobeincludedinthedesign documentation,andifappropriate,inthesupportrules.
Routinemonitoringandrecordingscheme
25 Whererockboltsareusedtosupportmineroadways,themanagerneedsto prepareaSchemefortheroutinemonitoringofroadways.
26 Themanagerneedstoappointasuitablyqualifiedandcompetentpersonto implement,auditandcoordinatethescheme.Asuitablequalificationwouldbea HigherNationalCertificateinaminingrelatedsubjecttogetherwithatleastsix monthsrelevantexperienceofstratacontrolactivitiesinacoalmineandthe completionofatrainingcourseinrockbolting.Forthepurposesofthisguidance thispersonisreferredtoastherockboltingcoordinator(coordinator).Where appropriate,sufficientsuitablytrainedandcompetentpeopleneedtobeappointed toassistintheperformanceoftheseduties.
27 Themanagersschemeneedstospecifythe:
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proceduresfortheauditingofroutinemonitoringdevicesinrockbolted roadways;
equipmenttobeused; dutiesofindividualsandtherequiredplans,schedulesandreports.
28 Theschemeneedstorecognisethe:
needtomonitorandreportphysicalchangesaffectingthesecurityofthe supportsystem;
needtotakeremedialmeasures; maximumlevelsofmovementallowedonthemonitoringdevicesbeforeaction
isrequired; actionstobetakenandthepersonresponsiblefortakingtheaction.
Routinemonitoringdevices
29 Twomaintypesofmonitoringdeviceareutilisedfortheroutinemonitoringof rockboltedroadways.Thesearedualheighttelltalesandmultihorizon extensometers.
Dualheighttelltales
30 Dualheighttelltalesgivevisualindicationofroofdilation.Theconstruction, installationprocedureandmethodofreadingdualheighttelltalesisshownin Appendix4.Thetelltalesneedtobeinstalled:
toatleasttwicetheheightoftheboltlengthor4.8m,whicheveristhegreater; atintervalsofnotgreaterthan20mmaximumdistance; ateveryjunction; atareasofknownorsuspectedinstability; atareasoflikelyinteractionfromoldandpresentworkings,andenlarged
excavations.
31 Telltalescanalsobesetatincreasedfrequenciesbypeopleworkingonsiteor throughsupervisoryormanagerialinstruction.
32 Telltalesneedtobeinstalledasnearverticalaspossibledrilledclosetothe centreoftheroadway,andasclosetothefaceoftheheadingaspracticable,oras directedbythecoordinator.
33 Atthesiteofeverytelltaleahighvisibilitysignneedstobeplacedbearinga uniquereferencecodetoenablethetelltaletobeeasilyidentifiedforreportingand recordingpurposes.
34 Alltelltaleswhichbecomedefective,obscuredoroutofrangeneedtobe replacedasquicklyaspossibleatthesameheightinthesameholeor,whenthisis notpossible,drillanewholeincloseproximity.Specificdutiesunderactionlevels mayalsoberequired.Whensomeonereplacesatelltale,thereadingoftheold telltaleneedstoberecordedandreportedinwritingthatithasbeenreplaced.This informationisthengiventoboththecommandsupervisorfortheareaandthecoordinator.Allreplacementtelltalesneedtobetoauniquecolourscheme.
35 Telltalesneedtobereadbysuitablytrainedandcompetentpeopleby:
observingthecolouredbands;or measuringthegraduationlines;orby electronicsystemstoamannedcontrolpoint.
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36 Theseniorofficialsattentionneedstobedrawntoanytelltalemovementin excessof25mmoneithertheAorBindicatororatthemanagersrulesaction level,whicheveristhelowerfigure.Managersrulesshouldalsodetailactionson theratesofmovementappropriateforthespecificminesite.
37 Forrecordingpurposesanytelltalereadingneedstoberelatedtotheunique referencecodeinparagraph33.
Multihorizonextensometers
38 Multihorizonextensometersaremonitoringdevicesdesignedtobeinstalledby a suitablytrainedandcompetentpersonandprovidedetailedinformationonroof dilationtoaminimumdistanceof7.0maboveroofheight.
39 Therearetwomaintypesofextensometer:
sonicextensometer; multiwireextensometer.
40 Theconstructionandinstallationofthesonicextensometerisshownin Appendix3andthatofthemultiwireextensometerinAppendix5.
41 Installmultihorizonextensometersforroutinemonitoringatmaximumintervals of200minanydirectionoratcloserfrequencywhereconditionsdemand.
42 Installmultihorizonextensometersforroutineroofmonitoringinverticalholes, drilledclosetothecentreoftheroadwayandasclosetothefaceoftheheading aspracticable,unlessdirecteddifferentlybythecoordinator.
43 Atthesiteofeverymultihorizonextensometer,placeasignbearingaunique referencecodetoenableittobeeasilyidentifiedforreportingandrecording purposes.
44 Multihorizonextensometersneedtobereadbysuitablytrained,competent andauthorisedpeopleusingtheappropriateequipment.Forrecordingpurposes, anyreadingneedstoberelatedtotheuniquereferencecode.Theinformationmay beelectronicallytransmittedtoacontrolpoint.
45 Replaceallroutinemonitoringmultihorizonextensometerswhichbecome defective,obscuredoroutofrangeasquicklyaspossible.Whereanymultihorizon extensometerisreplaced,amendthesigntoindicatesuchreplacement.The commandsupervisorfortheareaandthecoordinatorneedtobenotifiedin writingofanyreplacements.
Plansandschedules
Planofrockboltedroadways
46 Aplanneedstobepreparedandmaintainedtoindicatethepartsofthemine whererockboltsareusedasthemainmeansofsupport.Posttheplanwhereit canbeeasilyseenbyallthosewhohaveresponsibilitiesunderthemanagers schemebeforetheygounderground.Makesureitisreviewedweekly.
Scheduleofmeasurementzonesandmeasurementfrequency
47 Ascheduleneedstobemaintainedatthemine,listingallrockboltedroadways andtherequiredfrequencyofmeasurementofmonitoringdevicesinthose
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roadways.AnexampleisshowninAppendix6.Therecommendedfrequencyof measurementsisasfollows:
dualheighttelltaleswhichareinstalledinroadwayswithinInbyedistrictsneed to beobservedandreportedoneachshiftbytheinspectionofficialand measuredandrecordedatleastweekly;
allroutinemonitoringdevicesinstalledinsectionsofroadwayswhichareareas ofknownorsuspectedinstabilityneedtobemeasuredandrecordedatleast daily;
measureandrecordallotherroutinemonitoringdevicesatthemineatleast onceeachmonth;
whereanyadversereadingortrendisrecorded,measurementandrecording needtobecarriedoutforeachshift.
48 Divideeveryrockboltedareaofthemineintomeasurementzonestoenablethe systematicmeasurement,recordingandauditingofroutinemonitoringdevicesat theprescribedfrequency.
Inspectingofficialstelltalechecklists
49 Produceatelltalechecklistforeverydistrictcontainingrockboltedroadways andupdateitatleastweeklytotakeaccountofnewandreplacementtelltales.An examplechecklistisshowninAppendix7.
Dutiesofpeopleinrelationtotheminemonitoringscheme
Minemanager
50 Theminemanagerensuresthatamonitoringschemeisinplacetomaintain stabilityofmineroadwayssupportedbyrockbolts.Themanagerappointsacoordinatortomanageandcoordinatethescheme.
51 Intheabsenceofthecoordinator,themanagercanappointasimilarlytrained andcompetentpersontoactasasubstitute.
52 Themanagerappointssufficientsuitablytrainedandcompetentpeopleand grantsfacilitytoensurecompliancewiththescheme.
53 Themanagersetsthelevelofmovementatwhichactionistobetakenand specifiestheremedialmeasurestobetakenatthoselevels.
Minerockboltcoordinator
54 Thecoordinatorensuresthatthemanagersschemeforroutinemonitoringof rockboltedroadwaysisfullyimplementedandkeepsthemanagerinformed,sothat theschemeisregularlyupdated.
55 Thecoordinatorensuresthatcommandsupervisorsandinspectionofficials havetherequisiteinformationtoenablethemtofulfiltheirdutiesinrelationto supportofmineroadways.
56 Thecoordinatorhasthefollowingspecificduties:
toensurethatroutinemonitoringdevicesareinstalledorreplacedtothe standardandfrequencyspecified;
toensurethatthescheduleofmeasurementzonesandmeasuringfrequencyis maintained;
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toensurethatallrelevantworkersareinformedofthecurrentactionlevelsand thattheappropriateremedialactionsarebeingtaken;
to reporttothemanagertheresultsofremedialactionsandcontinued requirementsuntilapositionofstabilityisrecorded;
to ensurethatallroutinemonitoringdevicesattheminearemeasuredand recordedatthefrequencyspecifiedinthescheme;
toensurethatthemanagerortheirnominatedrepresentativeisinformedofany abnormalresultsonadailybasis;
tocollateandassessallinformationondefectsandabnormalitiesaffectingthe stabilityofrockboltedroadways.Thecoordinatorneedstoconferwith appropriatemembersofthemanagementstructureandadvisethemofthe requiredremedialaction;
toensurethatrecordsofallmeasurementsofroutinemonitoringdevicesand copiesoftheirreportstothemanageraremaintainedatthemineforatleast threeyears;
toensurethatanyreportedgeotechnicalfeaturesorchangeswhichmayaffect stabilityarebroughttotheattentionoftheappropriatemembersinthe managementstructure.
Inspectionofficials
57 Whereaninspectiondistrictincludesareasofrockboltedroadway,an inspectionofficialshouldvisuallyexamineeverydualheighttelltaleintheroadway andrecordanydefectsandabnormalitiesinthestatutoryreport.
58 Theinspectionofficialneedstoensure:
theyarefamiliarwiththepresenceofanyrockboltedroadwayswithinthat district;
theyhavetheappropriatetelltalechecklistsforthatdistrict; theyarefamiliarwiththeactionlevels;and duringtheirinspection,they:
readeverytelltalebyobservingthecolouredbandsandrecordonthe checklisttheconditionofeverytelltalewhichhasregisteredchange;
examinetheconditionofeverytelltaleandexaminewhethertheyareproperly identified;
ensuretelltalesareinstalledattheappropriatefrequencyandreplacedwhen necessary;
examinetheconditionofthesupportsystem;
examineforanygeotechnicalchangeorfeatures;
takeactiononanyadverseaspectfound.
59 Iftheinspectionofficialbelievesanydefectorabnormalityaffectingthestability ofarockboltedroadwayneedsmoreattention,theyshouldinformrelevantpeople assoonaspossible.Suchpeoplearetheappropriatecommandsupervisorsand theseniormembersofthemanagementstructureondutyatthemine.
60 Attheendoftheinspectionofficialsshift,thefollowinginformationshouldbe includedintheinspectionreport:
defectsorabnormalitiesaffectingthestabilityoftherockboltedroadways; defectsinthemonitoringsystem; telltalesreplacedduringtheshift; remedialworkcarriedout; remedialworkrequired; geotechnicalchange;and thosewhohavebeeninformedofthesematters.
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61 Attheendoftheshifttheyshouldsubmittheircompletedinspectionreport andtelltalechecklistasdesignatedbythemanager.
Surveyor
62 Thesurveyorshouldensurethattheplanofrockboltedroadwaysismaintained, reviewedandupdated.Theyhavetoinformthemanagerandthecoordinatorof anypredictedgeotechnicalchangeswhichmayaffectthestabilityofrockbolted roadways.
Operators
63 Operatorsshouldinstallrockbolts:
tothemanagerssupportrules; tothemanagersCodeofPractice; totheinstructionofacoordinatororofficial; accordingtothemanufacturers/suppliersinstructions.
Training
64 Allworkersinvolvedwithrockboltingneedtoreceivesuitabletraining(see Appendix8).Recordsofsuchtrainingareissuedtotheworkersinvolvedon successfulcompletionofthetraining.Additionaltrainingneedstobeprovided where circumstanceschangeandforrefresherpurposes.
Consumableitems
65 Allconsumableitemsformingpartoftheroadwaysupportsystemspecifiedin paragraphs1416mustbesuitableforthepurposewheninstalledincompliance withinstructionsprovidedbythesupplier.Aproductwouldberegardedassuitableif:
ithadreceivedanacceptancenumberundertheBritishCoalCorporations proceduresfortheAcceptanceofStrataReinforcementMaterialsand Equipmentbetween1April1992and30June1995;or
itcanbeshown,bymeansofindependentlyconductedandassessedtype testing,tomeetthecriteriasetoutinthedraftBritishStandardforStrata reinforcementsupportsystemcomponentsusedincoalmines; or
wherenocriteriaasreferredtoaboveexist,that: alaboratorytestprogrammeissetouttosimulate,ascloselyasis practicable,operationalconditions;
teststothisprogrammeareconductedbyanindependentaccreditedtest houseandareportisprepared;
theresultsofthetestareassessedindependentlyandfoundtobe satisfactory;
anassessmentofanyrisktosafetyand/orhealthhasbeencarriedout; thesupplieroftheproductisinpossessionofaletter,fromtheassessing body,settingouttheconditionsunderwhichtheproductmaybeused underground.Fieldtrialsmayberequiredtovalidateperformance.
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Appendix1UndergrounddeterminationofbondstrengthSteelrockbolt/resinsystemShortencapsulationpulltest
Introduction
Theshortencapsulationpulltestisusedtomeasuretheperformanceofa rockbolt/resin/rocksystem.Thetestisperformedundergroundandistheultimate prooftestofabolt/resin/rocksystem.Itshouldreplicatetheprocedures, consumablesandequipmentinuseforthesupport.
Briefdescription
A seriesofholesaredrilledtovaryingdepthsandboltsoftherequiredlengthare installedwithashortresincapsuletogiveanencapsulatedboltlengthofnotmore than300mm.Thepulltestneedstobeperformedafteracuringperiodofatleast 1 hourandnotmorethan24hours.Afterthistimeanaxialloadisappliedtothe endoftheboltandtheboltextensionmeasured.Theloadisappliedupto220kN oruntilthemaximumloadofthesystemhasbeenachieved,whicheveristhe greater.
Procedure
Equipment
Boreholemicrometer. Cabletiewrapsforpreparationofshortresincapsules. Knife. Tapemeasure. Pulltestequipmentcomprising:
asuitablehydraulicram; pressuregaugecapableofreadingpressuresequivalenttoaloadof300kN toanaccuracyofbetterthan10kN;
dialgaugecapableofreadingto0.01mm;
monopodtosupportdialgauge;
bearingplate;
drawbar;
shimsofvaryingthickness.
Note: Theramandpressuregaugeneedtobecalibratedregularly(ataminimum ofthreemonthlyintervals)toproduceaplotofpressureversusforceapplied.
Numberoftests
A minimumoftwotestsneedtobecarriedoutateachofthechosenroof horizons.Asanexample,fora2.4mbolt,thesehorizonswouldnormallybeat 600,1200,1800and2300mm.Ifsignificantchangesingeologyoccurwithinthe boltedhorizon,furthertestsneedtobecarriedoutatotherhorizonstodetermine theirinfluence,ifany,onthebondstrengthofanyproposedboltingsystem.
Boltpreparation
Theboltlengthneedstobeatleast40mmlongerthantheholelengthtoallowfull engagementofthedrawbaronthethreadedendofthebolt.Alltestbolts, includingfulllengthbolts,needtobecutsquaretotheboltaxis.
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Location
Placepulltestboltsascloseaspracticabletothefaceoftheheading.Choosea sectionofreasonablyflatroofwhichisnotsubjecttospalling.Thetestboltsshould notbeinstalledthroughmeshorstrapsandneedtobeatleast300mmapart. Boltsofthesamelengthneedtobeseparatedbyatleast1m.
Capsulepreparationandmeasurementofembedmentlength
Methodusingreamedouthole
Therockboltholeneedstobedrilledtothetopofthetesthorizonusingthe requiredbitandthenreamedouttoalargerdiametertowithin300mmofthehole depth.Thisprocedurewillensureaccurateknowledgeoftheencapsulationlength (Figures1aand1b).
Whentestinga22mmboltinanominal27mmdiameterhole,anembedment lengthof300mmisusuallyachievedwithacartridgelengthof170mm.
Preparethe170mmlongtestresincapsulesfromthefastsettingresinfoundin theheadingusingthetiewrapsandremovingtheexcesscapsule.Insertthebolt andresincartridgebyhandtoensuretheresincartridgeisnottornonthelip betweenthelargerandsmallerholes.Placealocatingmarkonthebolt correspondingtothecorrectinsertiondepthofboltandcartridgetoensurecorrect insertionintothesmallerhole(Figure1a).
Methodusingnonreamedhole
Theremaybeoccasionswhenthemethodsetoutinthelastthreeparagraphsis notappropriateforthesite.Thisisparticularlytruewhendrillingweakmudstones andflushingwithwater.Inthiscasequantitiesofthemixtureofmudstoneand watercanbeforcedbythereamerbitintothe300mmlongtestsection contaminatingthesurfaceofthetestborehole.Thiscoatingmaythenreducethe mechanicallockbetweenresinandrockleadingtospuriouspulltestresults.In thesecircumstancesreplacethereamedoutholemethodbythefollowing:
Drillholetolengthusingstandardbit. Measure:boreholediameter;boltdiameter;resincapsulediameter. Determinetheresincapsulelengthtoproducenotmorethan300mmbolt
encapsulationusingtheformula:
Capsulelength=(HoleD2 BoltD2 ) x encapsulatedlength CapsuleD2
Preparetestresincapsulesofthecalculatedlengthfromtheresinusedinthe headingusingthetiewrapsandremovingtheexcesscapsule.
Holepreparation
Thesamedrillingmachineandoperatorneedtobeusedthroughoutthetests.Use thedrillbitspecifiedforthesitefordrillingthetestholes.
Useanewbit. Measurethebitdiameterbeforeeachtest. Usewetdrillingunlessclearlystipulatedotherwise. Drillholestotherequireddepth. Usingaboreholemicrometer,determinethemeandiameteroverthetop
300mmoftheholebytakingseveralreadingsinthisregion.
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150 - 200 mm Cartridge (length not critical)
300 mmTesthorizon
Tape checks that the cartridge and boltare correctly inserted into small hole
300 mm Test horizon
Hole diameter over test horizon (typically 26 mm to 28 mm)
Jack
Enlarged hole(>30 mm)
Resin in largerhole has negligibleeffect on loadtransfer
Figure1aMethodofcheckingcorrectinsertionofboltintosmallhole
Figure1bArrangementofboltwithinsmallholeandenlargedholetoensure300mm encapsulation.
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Boltinstallation
Thesurfaceconditionofthetestsectionofboltneedstobefreefromrust,grease, paint,dirtoranyothersurfacecontaminant.
Insertthecapsuleandboltandpushthecapsuletothebackofthetesthole byhand.
Raisethemachinetotheboltandengage. Thrustandspintheboltslowlytothebackoftheholetakingthreetofive
seconds,afterwhichtheboltshouldbespunforatleastafurtherfiveseconds. Waitforasuitableperiod,30secondsforfastsetresinforexample,andthen
lowerthemachine. Identifythetestboltforlength,bymarkingtheroofand/ormakingasiteplan.
Pulltesting
Boltsneedtobepullednosoonerthanonehourandnolaterthan24hoursafter installation.Thisistoensurethattheresinhastimetocureandthatnotimedependentroofmovementmechanicallylockstheboltinthehole.
AssembletheequipmentasshowninFigure2.Aligntheramalongtheaxisoftheboltandmakesuretheboltisnotincontactwiththewallofthehole.Thisis bestachievedbyfirsttrimminganyloosematerialfromaroundthemouthofthe holeandthenaligningtheassemblybywedgingsteelshimsbetweentheroofand bearingplate.Whentheassemblyisfullyaligned,thestemofthedialgaugeis locatedintotheidentontheendofthepullbarsothatitisalsoinlinewiththeboltaxis.
Atleasttwoskilledoperatorsarerequiredtooperatethepumpandtoreadthedialgauge.
Applytheboltloadslowlyandsmoothlyandwithoutpause.Theboltdisplacement needstobenotedat10kNintervals.
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Embedded length300 mm
Bolt
Hydraulic ram
Dial gauge
Nut andbearing
plate
Hydraulic pumpwith force indicator
Drawbarcoupler
Figure2 Equipmentforpulltest
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Analysis
Computersoftwareisavailabletocalculatetheyieldbondstressofthe rock/resin/boltsystem.
Thesoftwareisbasedonthefollowingcalculations:
EExtensioninbolt= FxLF
S x x D2
4
Bonddisplacement=Measuredboltdisplacement(boltextension+drawbarextension)
Where:
F = Appliedforce(Newtons) LF = Boltfreelength(mm)=boltlength(encapsulatedlength+length
inpullbar) Es = Youngsmodulusforsteel(206000MPa) BoltD = Nominalboltdiameter(mm)
A graphofappliedforce(kN)vbonddisplacement(mm)needstobeplotted.The bondstrengthistheappliedforceatwhichtheslopeofthegraphfallsbelow20kN/mm.Wherethebondlengthisnot300mm,theresultsneedtobe correctedtoa300mmbondusingtheformula:
Correctedbondstrength(kN)=measuredbondstrength(kN)x300 encapsulationlength(mm
Thereportedresultsneedtoincludetheaveragemeasuredtestholediameterand theencapsulationlength.Asuggestedformatforapulltestlogsheetisshownin Figure 3.
Testrequirements
Ingeneral,theaveragebondstrengthover50%oftheholelengthneedstoexceed 130kNforabondlengthof300mm.Thisvalueisequivalenttoabondstressof5 MPaforatestholediameterof27.6mm.
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PULL
TE
ST RESULTS
COLL
IERY:
DISTR
ICT:
DAT
E:
MM:
BIT
TY
PE
:
BIT
:
ENCAPSULA
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NGTH
: TE
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BOLT
LENGTH
mm
BOLT
RIB
mm
BOLT
CORE
mm
HOLE
mm
RESIN
CAPSULE
mm
RESIN
LENGTH
mm
BOLT
FREE
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mm
kN
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REMARKS
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Figure3 Anexampleofapulltestlogsheet
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Appendix2Straingaugedrockbolts
Description
Straingaugedrockboltsareusedtomeasureaxialandbendingstrainsimposedon therockboltswheninstalledinaroadway.Thestraingaugedboltsreplacesomeor allofthenormalboltsintheboltingpattern.
Strainsaremeasuredusingpairsofstraingaugesattachedtooppositesidesofthe rockboltsatintervalsalongitslength.Fromthemeasuredstrains,theboltmean strainsandstraindifferencescanbecomputedatthestraingaugepositionand boltloadprofilesandbendingmomentsestimated.
Theboltsmustbecorrectlyinstalledandalignedtogiverepresentativeresults.
Specification
Thestraingaugedboltsneedtobemanufacturedfromactualrockboltsasusedin thesupportsystem,ie:
samesteel; samesurfaceprofile; samelength,diameters,threadetc.
Installthestraingaugesdiametricallyopposedinalignedpairsatintervalsalongthe axisofthebolts.
Makesurethemaximumdistanceofthefirstpairfromeachendoftheboltdoes notexceed0.2m.Makesurethemaximumaxialdistanceapartofgaugepairs doesnotexceed0.3m.
Theminimumnumberofgaugepairsforvariousboltlengthsaretherefore:
1.8mbolts6pairs; 2.1mbolts7pairs; 2.4mbolts8pairs; 2.7mbolts9pairs.
Forboltlengthsgreaterthan2.7m,thedistancebetweengaugepairsmaybe increasedbeyond0.3m,providingaminimumofninegaugepairsareinstalled.
Thestraingaugedboltshavetobecapableofbeinginstalledinanidentical mannertothatusedfornormalbolts.Makesuretheyareprovidedwithasuitable connectortoallowreadingofthegaugesbeforeandafterinstallation,using suitablemonitoringequipment.Theboltsneedtobesubjectedtotestingand qualitycontrolproceduresduringandaftermanufacture.
Installation
Installthestraingaugedboltsaspartofthenormalcycleofboltingoperations usingthesameequipment,consumablesandboltingpatternsasfornormalbolt installation.Readtheboltsshortlybeforeinstallationandagainassoonaspossible afterinstallation.Duringinstallationaligntheboltssothatthestraingaugepairsare alignedacrosstheroadwayormineopening(ietheboltaxialplanecontainingthe straingaugepairsisperpendiculartotheroadwayormineopeningaxis).
Thisisnecessarytoobtainmeasurementofthestraindifferenceatthegaugepairs duetolateralshearintheroadwayroof.
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Readingandresultsanalysis
UsesuitableI.S.instrumentation,cablesandconnectorstotakereadingsofthe analysisstraingaugesatthespecifiedintervals.Analysetheresultsusingsuitable computersoftware,intermsofmeanstrainsandstraindifferences,loadprofiles andbendingmoments.
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Appendix3Sonicextensometer
Introduction
Thesonicprobeextensometerisdesignedtomeasurethedistancebetweenpairs ofmagnetsupto10maparttoanaccuracyof0.02mm.
Theinstrumentconsistsofaflexibleprobewithatransducerheadattachedanda portablebatterypoweredreadoutunit.Theprobeisinsertedintoapredrilled hole,usuallyof43mmdiameter,containingupto20permanentmagnetswhich areanchoredtothestrata.Thismeasurementsystemisknownasthesonic extensometer(seeFigure4).
Installationprocedure
A verticalhole,atleast7mlong,isdrilledintothecentreoftheroofatthefaceof theheading.Aflexible,plastic,hollowtubeistheninsertedintheholeand anchoredinplace.Upto20permanentmagnetsarethen,inturn,placedaround thiscentralguidetubeandanchoredatpredeterminedintervalsalongthehole.
Readingsaretakenbyinsertingtheflexibleprobeinthecentralguidetubeand connectingtheprobetransducertothereadoutbox.Allmagnetdistancesare referredtothemagnetlocatedatthecollaroftheboreholeandthemagnet locationsaremeasuredinsequence.
Principleofoperation
Whenconnectedtothereadoutunit,theprobereceivesasmallcurrentpulse whichtravelsalongathinwalledmetaltubewithintheprobe.Ateachmagnet positiontheinteractionofthestaticfield(duetothemagnet)andthefield(dueto thecurrentpulse)producesatorsionaldeformationinthethinwalledtube.This deformationistransmitteddownthetubeasasonicpulseanddetectedbya torsionaltransducerlocatedattheendoftheprobe.Sonicpulsesfromeach magnetpositionarriveatthetransducerheadatdifferenttimes,dependingonhow fartheyhavetravelled.Thespeedofthemechanicallytransmitted,sonic,pulseis knownand,usingaveryaccuratetimer,thereadoutunitcalculatesanddisplays thepositionsofthemagnetswithhighresolution.
Results
Sonicextensometersoftwareisavailablewhichcanbeusedtoanalyseand presentthedatainavarietyofways,including:
totalroofmovementattheanchorpositionsatdifferenttimesorfaceadvance; strainbetweenanchorsatdifferenttimesorfaceadvance; totalmovementatindividualanchorpositionsplottedagainsttimeorface
advance.
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Guide tube anchoredat top of hole
Typically43 mm
MagnetAnchor
Up to 20 magnetsanchored to strata
Reference magnetand anchor
Sonic extensometer probeinserted in the guide tube
To readout
At least 7 metres
Figure4Sonicextensometer
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Appendix4Dualheighttelltale
Introduction
Dualheighttelltalesareavailableforuseinavarietyofholesizesfromnominal27mmdiametertonominal55mmdiameter.ThegeneralassemblyisshowninFigure5.
Installation
Drillhole,usingappropriatebitsize,totherequiredheight(2xboltheightor 4.8m,whicheverisgreater).
Insertreferencetubeandpushintight. Inserttopanchor,attachedtosmallestindicatorB,totopofhole.Checkfor
firmanchorage. Insertloweranchor,attachedtoIargerindicatorA,to0.3mbelowthebolted
height,eg2.1mfor2.4mbolt. PositionthetopofthegreenbandonindicatorAtobelevelwithbottomof
referencetube.Aligntoscale.Crimpferruleinposition. PositionthetopofthegreenbandonindicatorBtobelevelwithbottomof
indicatorA.Aligntoscale.Crimpferruleinposition. Recorddetails:positionofhole,dateandtime,anchorheights.
Readingmethods(seeFigure6)
1.Bycolour
Reportwholeandpartbandsvisible,forexample:
A:1/2green,yellow,red.
B:3/4yellow,red.
2.Byscale
Reportmeasurement,inmillimetres,liningupwithreferencemarkforeachanchor.
ReferenceforAisbottomofreferencetube.
ReferenceforBisbottomofindicatorA.
Scalehasmillimetredivisions,withcentimetremarks.Forexample:
A:12mm;
B:31mm.
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Interpretation
MovementofArelativetothereferencetubeisequaltothestrataexpansion withintheboltedheight.
MovementofBrelativetoitsreference(bottomofA)isequaltothestrata expansionbetween thetopoftheboltandtheupperanchorposition.
ThetotalstrataexpansionisAplusB. Expansionofstrataabovethetopanchorisnotdetected.
'A' Anchor
'B' Anchor
'A'
'B'
10
20
30
40
50
60
70
10
20
30
40
50
60
70
yellow
yellow
Referencetube
green
red
green
red
Figure5Dualheighttelltalegeneralassembly
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Action
See paragraphs54to60inthemaintextofthisdocument.
A
B
yellow
yellow
green
red
green
red
Readingbycolour
Readingbyscale
yellow
yellow
10
20
30
40
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60
70
10
20
30
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50
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70
ReferencepointforA
ReferencepointforB
green
red
green
red
Figure6Rockboltdualheighttelltalereadingmethods
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Appendix5Multiwireextensometers
Introduction
Themultiwireextensometerconsistsofa7mlong,verticalhole,usuallyof35mm diameter,drilledintothecentreoftheroofatthefaceoftheheading,containing fourseparatewires,eachanchoredatadifferentheight.Thewiresareterminated justbelowthebottomofthehole.Thesystemcanbereadmanuallybymeasuring thedistancefromareferencepointoneachwiretothemouthofthehole. Alternatively,aremotemonitoringsystemwithsuitabletransducersanddata transmissioncanbeemployed.
Principleofoperation
A diagramofthesystemisshowninFigure7.Thewiresareanchoredatdifferent heightsintheboreholeusingtwosimpleprongsprings.Thesearecheap,effective andeasilyinstalled.Therecommendedanchorageheightsofthespringsareas follows:
Minimum7m: Thehigherthetopspringisanchoredthemorelikelyitistobe anchoredinstableground.Thisisdesirableasthetopanchorprovidesthe referenceagainstwhichthemovementofalltheothersiscompared.
Boltlength+0.3m: Thisanchormeasuresroofdilationjustabovethebolted height.
Boltlength0.3m: Thisanchorisplacedattheboundarybetweenthebolted heightandtheroofabovetheboltedheight.Itisplacedbelowthetopofthe boltsasitispossibleforthetopsoftheboltstobewithdrawnfromthe overlyingstrataifroofdilationoccurswithinthetop0.3moftheboltedheight.
0.5m: Thisanchorisplacedbetweentheimmediateorlowerroof,whichcan bepronetospall,flakingandslabbing,andtherestoftheboltedheightwhich needstobefullystabilisedbytherockbolts.
Additionalanchorsmaybeplacedatotherheightsifrequired.Thiswouldbe appropriateif,forinstance,therewasanabruptchangeofrocktypewithinthe lengthofthehole.Theuseofmorethansixanchorsisnotrecommendedas thereisadangeroftanglingthewires.
Thepositionofeachanchorneedstobeaccuratelyrecorded.
Thewiresarebroughtthroughasuitablereferencepointplacedatthemouthofthe holeandareterminatedabout250mmbelowthereferencewithanelectrical connector.Thewireshavetobeuniquelylabelled.Numberedcollarsareusually usedforthispurpose.
Readingmethod
Placeresponsibilityforreadingthewireextensometerswithacompetentperson, asitrequirescare,accuracyandconsistency.Thatpersonalsoneedstobemade responsibleforrecordingthereadings,analysingthedataandprovidingtheresults tothemanagerofthemine,orarepresentative.
Clearlynumbereachextensometerandkeeparecordofitspositionandnumber.
Toreadanextensometer,hangaweight(suchasasafetylamp)fromeachwirein turnandmeasurethedistancebetweenthereferencepointandtheupperendof theelectricalconnector.Asteeltape,orruler,isadequatefortakingthereadings whichneedtoberecordedtothenearestmillimetre.Ensureeveryeffortismade forthesamepersontotakethereadingsusingthesametapetoreduceerrors. Recordboththedateandfacedistanceforeachsetofreadings.
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Results
Theresultsmaybegraphedbyhand.However,suitablesoftwarepackagesare availablewhichcanbeusedtoanalyseandpresentthedatainavarietyofways including:
totalroofmovementattheanchorpositionsatdifferenttimesorfaceadvance; strainbetweenanchorsatdifferenttimesorfaceadvance; totalmovementatindividualanchorpositionsplottedagainsttimeorface
advance.
1 3 24
1
2
3
4Stable reference anchor
7 metres
Figure7Multiwireextensometer
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Appendix6Exampleofscheduleofmeasurementzonesand measurementfrequencies
Location Zonenumber Measurementfrequency
Telltales Extensometers
WestParkgateA&BroadstoNo.5slit 1 W M
WestParkgateA&BroadsNo.5toNo.12slit 2 W M
WestParkgateA&BroadsNo.12toNo.15slit 3 W M
WestParkgateIntakeCroadQtoDT3 4 W M
WestParkgateIntakeEroadUtoSA4 5 M M
103sAccessA&Broads&DMReturn 6 M M
101sTailGateC&DroadstoNo.6slit 7 M M
101sTailGateC&DNo.6toNo.10slit 8 W M
101s TailGateC&DNo.10toNo.14slit 9 M M
101s TailGateC&DNo.14toNo.18slit 10 M M
101sTailGateC&DNo.18toNo.22slit 11 W M
101sTailGateC&DNo.19toNo.23slit 12 W M
* W = Weekly M = Monthly
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Appendix7Inspectingofficialstelltalechecklist
COLLIERY:....... SHIFT:.........DATE:........
INSPECTION DISTRICT:........ NO.TELLTALESONDISTRICT:...................
TELLTALENUMBER ACOLOUR BCOLOUR SIGNY/N ACTION/COMMENT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
PRINTNAME: SIGNATURE:.....................................
AlldefectsindicatedonthisformshallbeextractedandrecordedonyourDistrictInspectionReport.
ThisformshallbesubmittedtotheRegulation13.1(d)OfficewithyourDistrictInspectionReport.
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Appendix8Training
Trainingcoursesforthoseinvolvedinrockboltingneedtoincludethefollowing aspects:
Managers
Provideanunderstandingoftheforcespresentintherockandthe redistributionoftheseasaconsequenceofminingoperations.
Illustratethedifferencesbetweenconventionalsupportandrockbolting. Explaintheactionofrockboltsinlimitingroofmovementandroadway
deformation. Highlighttheadverseeffectsofpoorinstallationstandards. Provideanappreciationofmonitoringtechniquesandtheinformationobtained,
togetherwithdetailsoftheinstallationandinspectionproceduresforthetelltale monitoringsystemandalsothesettingofactionlevelsandassociatedactions.
Giveguidanceontheconstructionandimplementationofthemanagers schemefortheroutinemonitoringofrockboltedroadways.
Instructontheinspectionofboltedroofandribsforsignsofexcessivebolt loadingordeterioration,andtheactiontobetakenifthesearediscovered.
Rockboltingcoordinator
Anintroductiontorockmechanicsprinciplesasappliedtorockboltingincluding suchtopicsasstress,thestrata,designofreinforcementsystems, undergroundengineering,consumablesandseveraldetailedcasehistoriesand includesitevisitswherepossible.
Managementofthemanagersschemefortheroutinemonitoringofrockbolted roadways.
Installation,replacementandreadingofallroutinemonitoringdevicesusedat theirmine.
Familiarisationanduseoftheappropriatecomputersoftware. Settingofappropriateroutinemonitoringactionlevelsforeachareaofthe
mine. Settingofappropriatecorrespondingremedialactionforactionlevelsforeach
areaofthemine. Determinationofappropriatemeasuringfrequenciesforroutinemonitoring
deviceswithinthemine. Followuponremedialactionstosecurestability. Formulationandupdatingofthescheduleofmeasurementzonesand
measuringfrequencyandrelatedmeasuringtimetables. Productionofofficialstelltalechecklists.
Officials
Anappreciationofbasicrockmechanicsasappliedinrockbolting. Allaspectsoftheminemonitoringsystem. Actionlevels. Action,dutiesandresponsibilities. Remedialmeasures. Followupactions. Communicationlinks. Allaspectsofthetelltalechecklistsystemattheirmine. Appreciationoftelltales. Thecorrectinstallationoftelltales. Thereplacementoftelltales. Theidentificationoftelltales. Readingoftelltalesandappropriateactionlevelsandtheassociatedactionto
betaken.
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Instructionontheinspectionofboltedroofandribsforsignsofexcessivebolt loadingordeteriorationandtheactionstobetakenifthesearediscovered.
Appropriatetypesofextrasupporttosecuretheroofinadverseconditions.
Operators
Theactionofrockboltsandtypicalrockboltpatterns,highlightingthe importanceofgoodinstallationpractice.
Correctinstallationofrockboltsincludingadequate,practicalonsitetraining. Thesequenceofoperationsandthetimeatwhichrockboltingiscarriedout. Maintenanceoftherockboltingequipment(drillingmachinesetc)toensurethat
performanceismaintainedatdesignedlevels.Particularattentionneedstobe directedtoensureprovisionofasufficientsupplyofeitherhydraulicfluid,or compressedair,(asappropriate)toallowthedrillingequipmenttooperate withindesignparameters.
Provisionofthecorrectlengthofdrillrodinanundamagedconditionand arrangementstoensurethatthecorrectdepthofholeisdrilled(forexample premarkingthedrillrod).
Thetype,numberofcapsulesandsequenceofinsertionofresinintothehole, togetherwiththeimportanceoftherecommendedmixandwaittimes.
Anappreciationofthemanagersschemeforrockboltmonitoring,the informationindicatedbymeansofthetelltalemonitoringsystemandaction, whereappropriate.
Aninstructionthatoperators,intheeventofdifficultyintheapplicationof rockboltingandmonitoring,needtobringthosematterstotheattentionof thosehavingstatutoryresponsibilityforthesupervisionofoperations.
Wherecableboltsaretobeinstalledasadditionalsupport,operativesshould alsoreceivetrainingin: correctcableboltinstallationproceduresincludingonsitetraining; approvedconsumables; personalprotectiveequipment.
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Appendix9Standuptimeforextendedcutouts:Assessing extendedcutoutdistance
Whereadistancegreaterthanthatrequiredtosetthenextrockboltsupportiscut, thepossibleeffectofthisextendedcutoutonroofstabilityneedstobeassessed. Thisinvestigationoughttotaketheformofaprogressiveincreaseincutout distancetotheplannedvaluewithassessmentateachstageasfollows:
Assessexistinggeotechnicalinformationtoconfirmsitesuitabilityforan extendedcuttrialintermsofstrataconditions,totalroofmovement,rateof movementandpositionofroofstrainzones.
Excavatetheproposedincreasedcutoutdistanceatthetrialsitewithout exposingthedrivertounsupportedroof.
Donotinstallrockbolts. Installsufficienttemporarystandingsupporttoallowaremotereadingroof
extensometertobeinstalledhalfwayalongtheexcavatedsection. Removethetemporarysupportifappropriate. Monitorroofdilationviatheremotereadingextensometerforthemaximum
likelydelaytimebeforeboltsareinstalled(48hoursisconsideredtobea minimum).
Themeasuredpatternofroofdeformationshouldbecomparabletoprevious siteresults.Ifthereisnosignificantroofdeformationinthisperiod,anextended trialshouldtakeplaceasfollows:
(a)assesstheoveralleffectofthecutoutdistanceonroadwaystabilityby monitoring,eginstallationofadditionaltelltalesandextensometers.The assessmentneedstoincludethepossibilityofafalloverridingsupportedroof;
(b) iftheresultsoftheassessmentaresatisfactory,then,instages,increasethe cutoutdistancetotheproposedvalue.Eachstageneedstobesubjecttothe monitoringandassessmentdescribedin(a).
Theextendedcutoutdistanceneedstobeconsideredamaximumandvariedto suittheprevailinggeotechnicalconditions.
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Appendix10Liftingandsuspensionofequipmentin rockboltedroadways
1 Rockboltsinstalledforroofsupportpurposesshouldonlybeused(with suitableliftingshackles)forliftingorsuspendinglightloadsofuptoamaximumof 1 tonneonanindividualbolt,providedthattheloadonanyrowofboltsdoesnot exceed1tonneintotal.
2 Anyboltusedfortheliftingorsuspensionofequipmentotherthanasabove shouldbeananchorbolt.
3 Anchorboltsandtheirassociatedliftingshacklesshouldbesuitableforthe purposewheninstalledincompliancewithinstructionsprovidedbythesupplier. Theyshouldbereadilyidentifiableasanchorboltsbothbeforeandafterinstallation.
4 Themanagerofthemineshouldmakeruleswhichcovertheliftingor suspensionofequipmentinroadwayssupportedbyrockboltsandwhichtakeinto account:
thespecificationoftheboltsandliftingshackles; theweightoftheequipment; anyinducedloadthatmayactontheboltsorsuspensionequipment.(The
dynamicloadfromtheinflexionpointofatensionedconveyorisoneexample of aninducedload);
thenumberandlayoutoftheboltstoensurestabilityoftheequipment; themanufacturersinstructionsfortheinstallationanduseofthebolts; theintegrityoftheboltandtheeffectsofcorrosion; theadditionalimposedloadingonthestrata;and theneedforadditionalroofsupport.
5 Beforeanchorboltsareinstalledthecoordinatororacompetentperson appointedbythemanagershouldexamineandtest,ifnecessary,theroofstrata where theboltsaretobeinstalledtoensurethatthecurrentsupportisadequate andthestrataisinasuitablecondition.Thisinspectionshouldincludeinspectionof nearbymonitoringdevices.
6 Followingtheinstallationoftheanchorboltsandpriortosubsequentuse thereof,thecoordinatororacompetentpersonappointedbythemanagershould examinetheinstallationoftheanchorbolts,supplementedbytestsifnecessary,to confirmthattheyhavebeeninstalledinaccordancewiththemanagersrulesand theroofsupporthasnotdeterioratedsincethepreviousexamination.
7 Whereanchorboltsareinstalledforthepurposesofliftingorsuspensionof equipment,monitoringofthestratashouldbeincorporatedinthemanagersrules. Whereexistingmonitoringdevicesareremotefromthesiteandwouldnotbe representativeoftheimmediateareawheretheliftingoperationsaretotakeplace, dedicatedmonitoringshouldbeinstalledpriortolifting.Monitoringdevicesshould bereadbeforeandafterallliftingoperationsandshouldbemonitoredatregular intervalswhenliftingistakingplace.
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Furtherinformation
HSEpricedandfreepublicationsareavailablebymailorderfromHSEBooks,
POBox1999,Sudbury,SuffolkCO102WATel:01787881165Fax:01787313995
Website:www.hsebooks.co.uk(HSEpricedpublicationsarealsoavailablefrom
bookshopsandfreeleafletscanbedownloadedfromHSEswebsite:
www.hse.gov.uk.)
ForinformationabouthealthandsafetyringHSEsInfolineTel:08453450055
Fax:08454089566Textphone:08454089577email:hse.infoline@natbrit.comor
writetoHSEInformationServices,CaerphillyBusinessPark,CaerphillyCF833GG.
Thisdocumentisavailablewebonlyat:www.hse.gov.uk/pubns/mines01.pdf
CrowncopyrightThispublicationmaybefreelyreproduced,exceptfor
advertising,endorsementorcommercialpurposes.Firstpublished3/96.Please
acknowledgethesourceasHSE.
PublishedbytheHealthandSafetyExecutive Mines01 05/07 32 of32pages
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