1、Designation: D 4555 01 (Reapproved 2005)Standard Test Method forDetermining Deformability and Strength of Weak Rock by anIn Situ Uniaxial Compressive Test1This standard is issued under the fixed designation D 4555; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the measurement of the deform-ability and streng
3、th of large in situ specimens of weak rock bya uniaxial - compressive test. The test results take into accountthe effect of both intact material behavior and the behavior ofdiscontinuities contained within the specimen block.1.2 The values stated in SI units are to be regarded as thestandard.1.3 Thi
4、s 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 Document
5、s2.1 ASTM Standards:2D 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used In Engineering Design and Construction3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 rock quality designation, RQDa method for quanti-tat
6、ively describing the nature of a rock mass from core borings.RQD is obtained by measuring the total length of all unweath-ered pieces of core greater than or equal to 100 mm anddividing the total by the length of the particular core run. Thisquantity is expressed as a percent and is used to classify
7、 in siturock.3.1.2 weak rockrock containing numerous weatheredjoints spaced 30 to 500 mm, with gouge filling/waste rock withfines. Weak rock has both rock and soil properties dependingon condition of use. The compressive strength is less than 35MPa and the RQD is less than 50 %.4. Significance and U
8、se4.1 Since there is no reliable method of predicting theoverall strength and deformation data of a rock mass from theresults of laboratory tests on small specimens, in situ tests onlarge specimens are necessary. Such tests also have theadvantage that the rock specimen is tested under similarenviron
9、mental conditions as prevailing for the rock mass.4.2 Since the strength of rock is dependent on the size of thetest specimen, it is necessary to test several specimens (labo-ratory or field, or both) of progressively increasing size until anasymptotically constant strength value is found. This valu
10、e istaken to represent the strength of the rock mass.3,4NOTE 1Notwithstanding the statements on precision and bias con-tained in this test method; the precision of this test method is dependenton the competence of the personnel performing it, and the suitability of theequipment and facilities used.
11、Agencies that meet the criteria of PracticeD 3740 are generally considered capable of competent and objectivetesting. Users of this test method are cautioned that compliance withPractice D 3740 does not in itself assure reliable testing. Reliable testingdepends on many factors. Practice D 3740 provi
12、des a means of evaluatingsome of those factors.5. Apparatus5.1 Preparation EquipmentEquipment is needed for cut-ting specimen blocks from existing underground exposedfaces, for example, a coal cutting machine, pneumatic chisel, orother hand tools. No explosives are permitted.5.2 Loading System:5.2.1
13、 Hydraulic Jacks or FlatjacksThis equipment isrequired to apply a uniformly distributed load to the completeupper face of the specimen. The loading system shall be ofsufficient capacity and travel to load the system to failure.Multiple hydraulic jacks fed by a common manifold should beavoided.5.2.2
14、Hydraulic Pumping SystemThis system is needed tosupply oil at the required pressure to the jacks, the pressurebeing controlled to give a constant rate of displacement orstrain, rather than a constant rate of stress increase.1This test method is under the jurisdiction of Committee D18 on Soil and Roc
15、kand is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved July 1, 2005. Published November 2005. Originallyapproved in 1985. Last previous edition approved in 2001 as D 4555 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact A
16、STM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Bieniawski, Z. T., and Van Heerdan, W. L., “The Significance of Large-Scale InSitu Tests,” International Journal of Rock Mechanics Mining Sci
17、ences, Vol 1, 1975.4Heuze, F. E., “Scale Effects in the Determination of Rock Mass Strength andDeformability,” Rock Mechanics, Vol 12, 1980, pp 167192.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
18、n, PA 19428-2959, United States.NOTE 2Experience has shown that deformation-controlled loading ispreferable to stress-controlled loading because it results in a more stable,and thus safer, test. This result is a consequence of the strain softeningnature of most rock or rock-like materials. A single
19、stress level maycorrespond to different values of strain during any test, with the level ofstrain continuing to increase throughout a test. One way to achieveuniform deformation of the specimen is to use a separate pump for eachjack and to set the oil delivery rate of each pump to the same value.Sta
20、ndard diesel fuel injection pumps have been found suitable and arecapable of supplying pressures up to 100 MPa. The delivery rate of thesepumps can be set very accurately.5.3 Equipment to Measure Applied Load and Strain in theSpecimen:5.3.1 Load Measuring EquipmentThis equipment, forexample, electri
21、c, hydraulic, or mechanical load cells, permitsthe applied load to be measured with an accuracy better than65 % of the maximum in the test.5.3.2 Dial GageA dial gage, or similar displacementmeasuring devices, with robust fittings to enable the instru-ments to be mounted so that the strain in the cen
22、tral third ofeach specimen face is measured with an accuracy better than 6105. Strain is to be measured in the direction of applied loadand also in a perpendicular direction if Poissons ratio valuesare to be determined.5.4 Calibration EquipmentEquipment to calibrate theloading and displacement measu
23、ring systems, the accuracy ofcalibration to be better than the accuracies of test measurementspecified in 5.3.1 and 5.3.2.6. Procedure6.1 Preparation of Specimens:6.1.1 Cut specimens of the required dimensions from theexposed rock faces (Fig. 1). The specimen shall have aheight-to-minimum-width dime
24、nsion ratio of 2.0 to 2.5. Theratio of the maximum width of the specimen to the minimumwidth shall be as near to 1.0 as practicable.6.1.1.1 First, remove loose and damaged rock. Make verti-cal cuts as shown in Fig. 1 to form the vertical faces of thespecimen. Dimensional uniformity of each vertical
25、face of thetest specimen should not deviate by more than 20 mm. If thereis such deviation, abandon the specimen. Make a horizontal cutto form the top face of the specimen. Remove loose rock andtrim the specimen to final size using hand tools.NOTE 3Specimen dimensions cannot be specified because they
26、 de-pend very much on the rock properties, for example, the thickness of strataand the ease with which specimens can be prepared. It is recommendedthat a number of tests be done with a specimen with a width of about 0.5m and that the size of subsequent specimens should be increased until anasymptoti
27、cally constant strength value is reached. It is probable that thelargest test specimen will have a minimum width at least 10 times greaterthan the average dimension of the largest fragment defined by disconti-nuities.6.1.2 Clean and inspect the specimen. Record in detail thegeological structure of t
28、he block and nature of the reactionfaces of the block. Measure specimen geometry, including thegeometry of defects in the block, with an accuracy better than5 mm. Prepare photographs and drawings to illustrate bothgeological and geometric characteristics.6.1.3 Cast a concrete pad, suitably reinforce
29、d, to cover thetop face of the specimen (Fig. 2). This pad shall be sufficient togive adequate strength under the full applied load. The top faceof the pad shall be flat to within 65 of the basal plane of theblock.6.1.4 Remove the rock from above the specimen to makespace for the loading jacks. Cut
30、back the rock to a stratum ofsufficient strength to provide safe reaction. Generally, a con-crete reaction pad must be cast to distribute the load on the roofand to prevent undue deformation and movement of the jacksduring the test.The lower face of the reaction block shall be flatto within 65 mm an
31、d shall be parallel to the upper face of theFIG. 1 Sequence of Cuts and Excavation for SpecimenPreparationFIG. 2 Test ArrangementD 4555 01 (2005)2specimen block within 65. Cure all concrete for a sufficientperiod to provide adequate strength under the fully appliedload.NOTE 4If a suitably designed c
32、oncrete cap to the specimen is notemployed, the corners and sides of the specimen will often fail before thecentral portion. The corner jacks will then cease to operate, and the testresults will be suspect. The concrete cap should, if possible, be designedto ensure that the stress distributions in t
33、he top and bottom thirds of thespecimen are nearly identical.6.1.5 Install the loading jacks, platen, and load measuringequipment and check to ensure that they operate as intended.Install and check displacement measuring equipment. Calibrateall measuring instruments both before and after each test s
34、eries.6.2 Testing:6.2.1 Apply an initial load of approximately one-tenth of theestimated full test load and check the jacks to ensure that eachis in firm contact with the loading platen. Again checkdisplacement measuring equipment to ensure that it is rigidlymounted and is functioning correctly. Tak
35、e zero readings ofload and displacement.6.2.2 Increase the specimen load by applying the same slowand constant oil delivery to each jack. The rate of specimenstrain shall be constant across the test surface, such that adisplacement rate of between 5 and 15 mm/h is recorded ateach of the four faces o
36、f the specimen block.6.2.3 Record readings of applied load and displacement atintervals such that the load - displacement or stress - straincurve can be adequately defined. There shall be at least tenpoints on this curve, evenly spaced from zero to the failureload.6.2.4 Unless otherwise specified, t
37、erminate the test when thespecimen fails. Specimen failure is indicated by a drop ofhydraulic pressure to less than one-half the maximum applied,or by disintegration of the specimen to an extent that theloading system becomes inoperative or the test dangerous tocontinue. Record the mode of specimen
38、failure and make asketch of all developed cracks and failure surfaces.7. Calculation7.1 Calculate the uniaxial compressive strength of the speci-men by dividing the maximum load carried by the specimenduring the test by the original cross-sectional area of thespecimen.7.2 The deformation modulus for
39、 the specimen shall, unlessotherwise specified, be calculated as the tangent modulus Et50at one-half the peak uniaxial compressive strength. Thismodulus is found by drawing a tangent to the stress - straincurve at 50 % maximum load, the gradient of this tangent beingmeasured as Et50. Show on the str
40、ess - strain curve theconstruction and calculations used in deriving this, and anyother modulus values.7.3 A number of specimens of different sizes can be tested,and the trends in strength values due to size effects can beplotted graphically, as shown in Fig. 3.8. Report8.1 Report the following info
41、rmation:8.1.1 A diagram showing the details of the locations ofspecimens tested, the specimen numbering system used, andthe situation of each specimen with respect to the geology andgeometry of the site.8.1.2 Photographs, drawings, and tabulations giving fulldetails of the geological and geometrical
42、 characteristics of eachspecimen, preferably including index test data to characterizethe rock. Give particular attention to a detailed description ofthe pattern of joints, bedding planes, and other discontinuitiesin the specimen block.8.1.3 A description, with diagrams, of the test equipmentand met
43、hod used.8.1.4 Tabulated test results, including recorded values ofload and displacements, together with all derived data, calibra-tion results, and details of all corrections applied.8.1.5 Graphs showing load versus displacement or stressversus strain, including points representing all recorded dat
44、a,FIG. 3 Hypothetical Example Showing the Representation of Strength DataD 4555 01 (2005)3and a curve fitted to these points. Show the uniaxial compres-sive strength value, together with all constructions used indetermining the deformation modulus and other elastic param-eters. Show by diagram and d
45、escribe the mode of specimenfailure.8.1.6 Summary tables and graphs giving the values ofuniaxial compressive strength and deformation modulus, andshowing how these values vary as a function of specimen shapeand size and the character of the rock tested.9. Precision and Bias9.1 PrecisionDue to the na
46、ture of rock materials tested bythis test method, it is, at this time, either not feasible or toocostly to produce multiple specimens that have uniform physi-cal properties. Therefore, since specimens that would yield thesame test results cannot be tested, Subcommittee D18.12cannot determine the var
47、iation between tests since any varia-tion observed is just as likely to be due to specimen variationas to operator or laboratory testing variation. SubcommitteeD18.12 welcomes proposals to resolve this problem that wouldallow for development of a valid precision statement.9.2 BiasThere is no accepte
48、d reference value for this testmethod; therefore, bias cannot be determined.10. Keywords10.1 compression testing; deformation; in situ stress loadingtestsSUMMARY OF CHANGESIn accordance with Committee D18 policy, this section identifies the location of changes made to this standardsince the last edi
49、tion (2001) that may impact the use of this test method.(1) Updated footnote 1 information. (2) Updated footnote 2 information.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewe
