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J~7. 0"110' flood. Brlntwood. E••••• CM15 9AU. England

Rock anchors ·state of the art

by G. S. LITTLEJOHN, BSe. PhD, MICE, MIStructE. FGS,and D. A. BRUCE, BSe. AMICE. FGS

Originally published in 'Ground Engineering' magazine between May 1975 and May 1976

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ContentsPage 1

11

PART 1 : DESIGNGENERAL INTRODUCTIONDESIGN - AN INTRODUCTIONUPLIFT CAPACITY OF TH!; ROCK ANCHOR

SYSTEMDesign proceduresExperimental evidenceSpacingRemarksBOND BETWEEN CEMENT GROUT AND ROCKIntroductionFixed anchor designFixed anchor dimensionsTheoretical evidenceExperimental evidenceRemarks

BOND BETWEEN CEMENT GROUT AND STEELTENDON

112233335678

IntroductionThe mechanisms of bondFixed anchor designDistribution of bondMagnitude of bondEffect of rust on bondRemarksTENDONIntroductionTendon characteristicsAllowable stresses and safety factorsTendon spacersRemarksGENERAL CONCLUSIONS

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1012121212121214151515

PART 2: CONSTRUCTIONINTRODUCTIONDRILLINGIntroductionDrilling methodsChoice of drilling methodDrilling equipmentDrilling ratesFlushingAlignment and deviationWATER TESTING AND WATERPROOFINGTENDONStorage and handlingFabrication

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HomingGROUTS AND GROUTINGGrout compositionAdmixturesGrout crushing strengthMixingGrouting methods 25Grouting pressures 25Quality control 26CORROSION AND CORROSION PROTECTION 27Mechanisms and causes of corrosion 27Classification of groundwater aggressiveness 28Degree of protection recommended in practice 28Corrosion protection systems employed in practice 29

Special test anchorsMonitoring of the overall anchor rock structure

systemSERVICE BEHAVIOUR OF PRODUCTION

ANCHORSIntroductionTime - dependant behaviour of steel tendonsRelaxationCreepField observationsRemarksGENERAL CONCLUSIONSACKNOWLEDGEMENTS

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PART 3: STRESSING AND TESTINGINTRODUCTIONSTRESSINGMode of stressingPractical aspects of stressingChoice of stressing systemMonitoring proceduresPresentationInterpretationRemarksTESTINGPrecontract component testingAcceptance testing of production anchorsLong term monitoring of selected production

anchors

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