1、Designation: D4435 13Standard Test Method forRock Bolt Anchor Pull Test1This standard is issued under the fixed designation D4435; 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 i
2、ndicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 The objective of this test method is to measure theworking and ultimate capacities of a rock bolt anchor. Thismethod does not measure the entire roof support
3、 system. Thismethod also does not include tests for pretensioned bolts ormine roof support system evaluation.1.2 This test method is applicable to mechanical, cementgrout, resin, (epoxy, polyester, and the like), or other similaranchor systems.1.3 The values stated in inch-pound units are to be rega
4、rdedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard. Reporting of test results inunits other than inch-pound shall not be regarded as noncon-formance with this test method.1.3.1 The gravitation
5、al system of inch-pound units is usedwhen dealing with inch-pound units. In this system, the pound(lbf) represents a unit of force (weight), while the unit for massis slugs.1.4 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractic
6、e D6026.1.4.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation,
7、 purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant dig
8、its used in analyticalmethods for engineering design.1.5 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 o
9、f regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 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 ConstructionD6026 Pr
10、actice for Using Significant Digits in GeotechnicalData3. Terminology3.1 DefinitionsFor definitions of common technical termsin this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 displacementthe movement of the rock bolt head.3.2.2 failurein rock bolt t
11、esting, failure is defined as theinability of the anchor system or rock to sustain increased loadwithout rapidly increasing deformation. In some instances, thepeak load itself cannot be sustained.3.2.3 loadthe total axial force on the rock bolt.3.2.4 ultimate capacitythe maximum load sustained bythe
12、 anchor system.3.2.5 working capacitythe load on the anchor system atwhich significantly increasing displacement begins.4. Summary of Test Method4.1 A rock bolt is installed in the same manner and in thesame material as its intended construction use. The bolt ispulled hydraulically and the displacem
13、ent of the bolt head ismeasured concurrently. The bolt is pulled until the anchorsystem or rock fails. The ultimate and working capacities of thebolt are calculated from the plot of load versus displacement.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the d
14、irect responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1984. Last previous edition approved in 2008 as D4435 08. DOI:10.1520/D4435-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
16、t Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Rock bolts are used for support in a variety of miningand civil engineering situations.3The pull test may be used toprovide a quantitative measure of the relative performance ofdifferent anchor systems in the same rock type.Anch
17、or systemsmay be different mechanical anchors or different bond materi-als or lengths for grouted anchors. Such data can be used tochoose an anchor type and determine bolt length, spacing, andsize.5.2 The objective of the method is to measure anchorperformance, and not the performance of the rock bo
18、lt itself.Thus, to make sure the bolt response during the test is minimaland predictable, high strength, short-length (6 to 8 ft (1.8 to 2.5m) bolts have been specified. The bolt should be just longenough to make sure that failure occurs in the anchor systemand not from the reaction pad bearing down
19、 on the rock mass.5.3 Ideally, the rock bolt anchor should fail by shear at theanchor-rock interface or bond. Therefore, the local character-istics of the rock, such as roughness and induced fractures, aresignificant factors in the anchor strength. To obtain realisticstrength values, the test holes
20、should be drilled using the samemethods as the construction rock bolt holes.5.4 Rocks with significant time-dependent behavior, such asrock salt or shale, may respond to the anchor system itself andchange the anchor strength. In these cases, considerationshould be given to testing bolts over a perio
21、d of time.5.5 In establishing a testing program, the following factorsshould be considered:5.5.1 Anchor pull tests should be conducted in all rock typesin which construction bolts will be installed. If the rock isanisotropic, for example, bedded or schistose, the tests shouldbe conducted in various
22、orientations relative to the anisotropy,including those at which the construction bolt may be installed.5.5.2 In each rock type, at each orientation, and for eachanchor system, a sufficient number of tests should be con-ducted to determine the average bolt capacities within a fixeduncertainty at the
23、 95 % confidence level. The allowable uncer-tainty band depends on the project and involves such factors asthe rock quality, expected project lifetime, and importance ofthe areas to be bolted. Its determination will require consider-able engineering judgment. As a rough guideline, at least 10 to12 p
24、ull tests for a single set of variables have been foundnecessary to satisfy the statistical requirements.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet
25、 thecriteria of Practice D3740 are generally considered capable of competentand objective testing. Users of this test method are cautioned thatcompliance with Practice D3740 does not in itself assure reliable results. Reliable results depends on many factors; Practice D3740 provides ameans of evalua
26、ting some of those factors.6. Apparatus6.1 Loading SystemThe system for pulling the rock boltsshall consist of a hollow-center hydraulic ram and mounting/reaction frame. The hydraulic ram shall be of sufficientcapacity to fail the anchor and shall have a travel range of atleast 2 in. (50 mm). The mo
27、unting/reaction frame shall beusable against uneven rock surfaces. The loading system shallapply a force that deviates by no more than 5 from the longaxis of the bolt during the test.6.2 Load TransducerAn electronic load cell is recom-mended to measure the load on the rock bolt. The cell shallhave a
28、n accuracy of at least 6200 lbf (6890 N), includingerrors introduced by the excitation and readout system, and aresolution of at least 100 lbf (445 N). Other types of loadtransducers may be used if their performance meets thesespecifications. Alternatively, a pressure gauge or electronictransducer m
29、ay be used to measure the pressure applied to theram, provided the load measurement requirements above aresatisfied, including the effects of friction in the hydraulic ram,and the like.6.3 Displacement TransducerA dial gauge is recom-mended to measure the displacement of the rock bolt head. Itshall
30、have an accuracy of at least 60.001 in. (0.025 mm), aresolution of at least 0.0005 in. (0.013 mm), and a range of atleast 2 in. (50 mm). It shall be mounted along the axis of therock bolt within 5. The end of the rock bolt, or pulling rod ifused, shall be smooth with a counter-sink area approximatel
31、y14 in. (6 mm) in diameter to accommodate the measuring tip ofthe dial gauge. Other types of displacement transducers may beused provided they satisfy the requirements of this section.6.4 Displacement Transducer Support The displacementtransducer shall be supported from a point no closer than 3 ft(0
32、.9 m) to the reaction frame, if attached to the same rock face.The support shall be sufficiently rigid such that no deflection orinstability occurs during testing.6.5 Anchor SystemsThe anchors used for testing shall befrom the manufacturers standard production stock. Mechani-cal anchors shall be ins
33、pected to make sure that no defectiveanchors are tested. Mechanical anchors should be of correctsize for the hole diameter and the anchorage size should beknown. Grout or resin shall be fresh (within the shelf life) andobtained from unopened containers. If grouted anchors are tobe tested, make sure
34、resin cartridge sizes are compatible withhole diameter, rock bolt bar diameter and length of anchoragerequired. For anchorages utilizing injected grout, make suremixing and injection equipment and systems are compatiblewith manufacturers recommendations.6.6 Rock Bolt and AccessoriesThe rock bolt sha
35、ll be ofsufficient diameter and strength that its elastic range is notexceeded during testing. Standard bearing plates, washers, andthe like may be used as required.6.7 Drilling EquipmentThe same type of drilling equip-ment and drill bits that will be used for installing rock boltsduring the constru
36、ction phase of the project shall be used asmuch as practical to drill the test holes.3For additional information see, “Suggested Method for Determining theStrength of a Rock Bolt Anchor (Pull Test),”Suggested Methods for Rock BoltTesting, International Society for Rock Mechanics Commission on Standa
37、rdizationof Laboratory and Field Tests, 1974.D4435 1326.8 Torque WrenchIf expandable shell mechanical an-chors are used, a torque wrench shall be used to set them. Thewrench shall have a capacity at least 20 % greater than themanufacturers recommended anchor-setting torque. Thetorque wrench shall ha
38、ve an accuracy of at least 62 % of thefull-scale reading, and a resolution of at least 1 % of thefull-scale reading.6.9 Borehole Diameter Measuring Gauge A gauge shallbe used to measure the diameter of the borehole at the anchorlocation. It shall have an accuracy of at least 60.02 in. (0.5mm) and re
39、solution of at least 0.01 in. (0.25 mm)6.10 ThermometerA thermometer shall be used to mea-sure temperature in the borehole, within the anchor zone ifresin or cement grout anchorages are being tested. The tem-perature of the resin or grout shall also be measured at the timeof injection. The thermomet
40、er should have an accuracy of atleast 60.5F (60.1C) and a resolution of at least 1F (0.5C).See Note 2.6.11 Fig. 1 shows a typical test setup.NOTE 2The accuracy and resolution for the thermometer are pre-sented in both Fahrenheit and Celsius units such that either type ofthermometer can be used as lo
41、ng as the accuracy and resolution require-ments as stated are met. The Celsius values are not direct conversionsfrom Fahrenheit.7. Procedure7.1 Drilling the Test Hole:7.1.1 Drill the test hole using the same procedure that willbe used during construction. Wash or blow the borehole cleanof all cuttin
42、gs.7.1.2 The hole need not be as deep as the proposed length ofthe rock bolts. It shall, however, be deep enough to set theanchor past the zone of disturbance caused by the excavationand the zone of stress concentration caused by the reaction ofthe pulling frame. For mechanical shell anchors, drill
43、the hole1 ft (0.3 m) past the end of the anchor. A hole approximately 6ft. (1.8 m) in length has generally been found to be adequate.7.1.3 Inspect the test hole visually using a flashlight ormirror to reflect sunlight down the hole. If more than one halfof the bottom of the hole cannot be seen, the
44、hole is notsufficiently straight for a pull test and shall not be used.7.1.4 Measure and record to the nearest 0.01 in. (0.25 mm)the test hole diameter in two perpendicular directions at the topand bottom of the anchor location borehole using a diametermeasuring gauge for a total of four measurement
45、s.7.2 Preparation of AnchorsIf any anchor preparations,such as degreasing or rust removal, will be done duringconstruction, prepare the test anchors in the same way. If nospecial preparation will be done during construction, do notprepare the test anchors.7.3 Setting the Anchor:7.3.1 If mechanical a
46、nchors are used, lightly lubricate thedownhole end of the rock bolt and screw on the anchor. Whenin position, torque the bolt to the manufacturers recommendedlevel to set the anchor. A pair of jam-nuts on the upper end ofthe rod may be used to apply torque without producing axialload in the bolt. If
47、 the manufacturers torque cannot beachieved because of anchor rotational slippage due to shearfailure in the rock, note the maximum torque reading andinstall subsequent anchors to 80 % of this value. Do not testanchors where rotation occurs between the rock surface and theanchor. In all cases, recor
48、d any slipping or other anomalousbehavior as shown in Fig. 2.7.3.2 Install cement grout or resin anchors according to themanufacturers recommendations.FIG. 1 Typical Rock Bolt Pull Test SchematicD4435 1337.4 Testing Method:7.4.1 All tests are performed on untensioned bolts. Measureand record the tem
49、perature in the borehole within the anchorzone, the temperature of the resin or grout at the time ofinjection, and the ambient air temperature to the nearest 1F(0.5C). Ideally the test anchorages should be installed underthe same temperature conditions as expected during construc-tion. The time required for resin or grout anchorages to reachtheir design strengths is temperature dependent and may varysignificantly. Consult the resin or grout manufacturers litera-ture for recommended curing times under various temperatureconditions. Curing times
