ASTM_D_7401_-_08.pdf

Designation:D740108Standard Test Methods forLaboratory Determination of Rock Anchor Capacities by Pulland Drop Tests1This standard is issued under the fixed designation D7401;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover the quantitative determinationof the working and ultimate static or dynamic capacities of fullscale rock anchors.Dynamic capacities are determined tosimulate rockburst and blasting conditions(1).2The rockanchors are installed in steel pipe to simulate standard bore-holes sizes.Rock anchor capacities are determined as afunction of resin to steel bolt bond strength and steel bolt yieldstrength.These tests are not intended to determine rock anchorto borehole rock surface shear strength.1.2 These test methods are applicable to mechanical,resin,or other similar anchor systems.1.3 Two methods are provided to determine the capacities ofrock anchors,as follows:1.3.1 Method AUsing a horizontal hydraulically loadedpull test system.1.3.2 Method BUsing a vertical dynamically loaded droptest system.1.4 The values stated in SI units are to be regarded as thestandard.No other units of measurement are included in thisstandard.1.5 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil,Rock,and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4435 Test Method for Rock Bolt Anchor Pull TestD4436 Test Method for Rock Bolt Long-Term Load Reten-tion TestD6026 Practice for Using Significant Digits in GeotechnicalData3.Terminology3.1 DefinitionsRefer to Terminology D653 for specificdefinitions.3.2 Definitions of Terms Specific to This Standard:3.2.1 linescan cameraa camera with high optical linearresolution that captures two-dimensional images by moving theobject perpendicularly to the scan line.3.2.2 maximum loadrepresents the highest load valuerecorded during the test.3.2.3 rock anchorusually constructed of steel,which isinserted into pre-drilled holes in rock and secured with a fixingagent for the purpose of ground control.3.2.4 RPMacronym for revolutions per minute.3.2.5 transverse stiffnessthe ability of the borehole or steeltube wall to deform radially.3.2.6 yield loadcorresponds to the onset of plastic defor-mation.4.Summary of Test Methods4.1 A rock anchor is installed in a steel pipe instead of aborehole the same manner and in the same material as its1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.12 on RockMechanics.Current edition approved Jan.1,2008.Published February 2008.DOI:10.1520/D7401-08.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 intended use(2).In the Pull test,the rock anchor is hydrauli-cally pulled horizontally and the displacement of the bolt headis measured concurrently.The bolt is pulled until the anchorsystem fails(or to the ultimate stroke of the ram).The ultimateand working capacity of the rock anchor is calculated from theplot of load versus displacement.In the Drop test,a knownmass is released vertically impacting on a plate at a presetdistance that is in turn affixed to the end of a rock anchor.Themaximum energy is expressed in kJ.5.Significance and Use5.1 For a support system to be fully effective,the supportsystem must be able to contain the movement of rock materialdue to excavation stress release,slabbing,etc.Data from theload tests are used by engineers to design the appropriatesupport system to improve safety and stability of undergroundsupport systems.Test Methods D4435 and D4436 are used forin-situ load tests.5.2 The local characteristics of the rock,such as roughnessand induced fractures,are significant factors in the anchorstrength.The material used to simulate the borehole surfaceshould be sufficiently roughened so that failure occurs in therock anchor and not at the simulated a