1、Designation: D 4971 02 (Reapproved 2006)Standard Test Method forDetermining the In Situ Modulus of Deformation of RockUsing the Diametrically Loaded 76-mm (3-in.) BoreholeJack1This standard is issued under the fixed designation D 4971; the number immediately following the designation indicates the y
2、ear 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the estimation of in situmo
3、dulus of a rock mass at various depths and orientations.Information on time-dependent deformation may also be ob-tained.1.2 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.2.1 The method used to specify how data ar
4、e collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses, or both. How one applies the results obtained using thisstandard is beyond its scope.1.3 The values stated in SI units are regarded as standard.The inc
5、h-pound units in parentheses are for information only.1.4 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
6、of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD
7、 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6032 Test Method for Determining Rock Quality Desig-nation (RQD) of Rock Core3. Terminology3.1 See Terminology D 653 for general definitions.3.2 Definitions of Terms Specific to This Standard:3.2.1 deformationchange in shape or size,
8、 (see Terminol-ogy D 653). In this test method deformation is the change inthe diameter of the borehole.3.2.2 modulus of deformationratio of stress to strain for amaterial under given loading conditions; numerically equal tothe slope of the tangent or the secant of the stress-strain curve.The use of
9、 the term modulus of elasticity is recommended formaterials that deform in accordance with Hookes law, and theterm modulus of deformation is recommended for materialsthat deform otherwise, (see Terminology D 653). In this testmethod, the modulus of deformation is calculated from theapplied fluid pre
10、ssure, the relative change in hole diameter, afunction of Poissons ratio, and a constant.3.2.3 jack effciencyratio of the jack plate pressure to theapplied hydraulic pressure.4. Summary of Test Method4.1 The 76 mm (3.0 in.) jacks, (see Fig. 1 and Fig. 2), induceundirectional pressure to the walls of
11、 a borehole by means oftwo opposed curved steel platens each covering a 90 sector,over a length of 20.3 cm (8 in.).4.2 Raw data from a test consist of hydraulic-line pressure,Qh, versus readout from linear variable differential transform-ers (LVDTs) measuring platen movement. Knowing the dis-placeme
12、nt calibration of the LVDTs, the raw data can betransformed to a test record of hydraulic pressure versus holediameter, D. For each increment of pressure, DQh, and holedeformation, DD, theoretical data analysis (1),3assuming rigidjack plates and full 90 contact, give the theoretical rock massmodulus
13、, E (Etheoretical) as a function E=f (D QhDD T*),1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.Current edition approved May 1, 2006. Published June 2006 Originallyapproved in 1989. Last previ
14、ous edition approved in 2002 as D 497102.2For 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.3The boldface number
15、s in parentheses refer to a list of references at the end ofthe standard.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where T* is a coefficient dependent upon Poiss
16、ons ratio. If Eis measured on a linear segment of the loading curve, commonterminology is modulus of deformation. If E is measured on anunloading linear segment, it is referred to as the recoverymodulus.5. Significance and Use5.1 Results of this test method are used to predict displace-ments in rock
17、 mass caused by loads from a structure or fromunderground construction. It is one of several tests that shouldbe performed.5.2 Because the jack can apply directed loads, this testmethod can be performed to provide an estimate of anisotropy.5.3 In theory, the analysis of test data is straight forward
18、; themodulus estimate requires a record of applied hydraulicpressure versus borehole diameter change, and a knowledge ofthe rocks Poissons ratio. In practice, the above procedure,using the original theoretical formula, frequently has resultedin computing a material modulus that was demonstrably tool
19、ow.5.4 For analyzing the test data it is assumed that the rockmass is linearly elastic, isotropic, and homogeneous. Withinthese assumptions, this test method can provide useful data forrock masses for which equivalent continuous properties can notbe found or estimated.NOTE 1Notwithstanding the state
20、ments 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. Agencies that meet the criteria of PracticeD 3740 are generally considered capable of c
21、ompetent 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 provides a means of evaluatingsome of those factors.6. Interferences6.1 It is assumed that t
22、he tensile and compressive moduli ofthe rock are equal and there is no tensile cracking induced inthe rock mass because of jack loading. If tensile cracks arecreated at 90 to the loading direction, it has been shown (1)that the calculated modulus values can decrease by up to 29 %.Therefore, tensile
23、cracking would result in a decrease in theslope of the loading curve and test data in the region ofdecreased slope should not be used.6.2 The volume of rock mass involved in the 76 mm (3.0in.) diameter jack test has been estimated (2) to be about 0.15m3(5 ft3). This volume may not include enough dis
24、continuitiesto be representative of the rock mass on a larger scale.6.3 Two aspects of jack behavior, discussed in 6.3.1 and6.3.2, require careful consideration in the analysis of test dataand can be compensated for by the procedure outlined in thistest method and detailed by Heuze and Amadei (3).6.
25、3.1 The platen/rock contact may not cover 90 of theborehole circumference, as assumed, because of radius mis-match between the jack and the hole (4, 5).6.3.2 In rock with modulus of deformation greater thanabout 7 GPa (106psi), there is a longitudinal concave outwardbending of the jack platens that
26、requires correction. ThisFIG. 1 The 76-mm (3-in.) Borehole JackFIG. 2 Schematic of Loading of the Borehole JackD 4971 02 (2006)2correction is necessary because the bending gives higherdisplacements at the ends than at the center of the loadingplatens and LVDT displacement gages are located near thee
27、nds of the platens.7. Apparatus7.1 Borehole JackThe borehole jack for which equationsand corrections are presented in Section 12 is the so-called“hard rock” jack, that is currently manufactured under patent.The manufacturers specifications are: range of travel is 13 mm(0.5 in.) from closed at 70 mm
28、(2.75 in.) to fully open at 83 mm(3.25 in.), maximum pressure on borehole wall is 64 MPa(9300 psi), and deformation resolution is 0.025 mm (0.001 in.).The maximum jack pressure is achieved with a hydraulicsystem pressure of 69 MPa (10 000 psi). Deformation ismeasured by an LVDT at each end of the lo
29、ading platens.These are referred to as the near and far LVDT respectively.7.2 Pressure GageA hydraulic gage or electronic trans-ducer may be used to measure the hydraulic system pressure.The gage shall have an accuracy of at least 280 kPa (40 psi),including errors introduced by the readout equipment
30、, and aresolution of at least 140 kPa (20 psi).7.3 Casing Alignment SystemThe borehole jack is at-tached to 73 mm (2.875 in.) BX drill casing and placed intoposition in the borehole. To determine the orientation of thejack, an orientation mark is transferred to successive sectionsof casing as they a
31、re added. To avoid introducing a systematicand progressive error into orientation, an alignment deviceshall be used to transfer the mark from one casing section toanother. In vertical boreholes, a plumb line may be sufficient.In inclined or horizontal boreholes, a marking guide such as theone shown
32、on Fig. 3 has been found satisfactory (6).8. Sampling, Test Specimens, and Test Units8.1 Number and Orientation of BoreholesThe number,spacing, and orientation of boreholes depend on the geometryof the project and the geology of the site.8.2 Rock Sampling:8.2.1 Each type of rock should be tested. In
33、 addition, areasof low modulus of deformation, such as fracture or alterationzones within a rock mass, are of particular interest and shouldbe tested.8.2.2 Tests should be conducted at different orientations tosample the anistropy of the rock mass, for example, paralleland perpendicular to the long
34、axes of the columns in a basaltflow. Boreholes should generally be orthogonal to each otherand either parallel or perpendicular to the structure of the rockformation. At least ten tests in each rock material are recom-mended.8.3 Boreholes ReamedIt is recommended that a reamingshell with a nominal ou
35、tside diameter of 76 mm (3 in.) be used.It is further recommended that a bit fabricated to reaming shellgage 76 mm (3 in.) also be used. This will minimize the radiusmismatch between the borehole and the jack. Accurate mea-surement of the diameter of the borehole is important.8.4 Boreholes CoredThe
36、boreholes shall be drilled usingdiamond core techniques; continuous core should be obtained.Oriented cores are desirable but not mandatory.8.5 Core LoggedThe recovered core should be com-pletely logged, with emphasis on fractures and other mechani-cal inhomogeneties and water pressure. Rock quality
37、designa-tion (RQD) should be calculated for each 1.5 m (5 ft) of holecored or core ru, in accordance with Test Method D 6032.8.6 Test LocationWithin each borehole, locations for eachtest should be selected based on the core logs. In some casesobservation of the borehole with a borescope or boreholec
38、amera (film or television) may be useful.9. Personnel and Equipment Requirements9.1 PersonnelAll personnel involved in performing thetest, including technicians and test supervisors, should be underthe guidance of someone thoroughly familiar with the use ofthe jack. Sometimes the personnel may be re
39、quired to beformally pre-qualified under a quality assurance (QA) proce-dures established as part of the overall testing program.9.2 Equipment Performance Verification The complianceof all equipment and apparatus with performance specificationsof this procedure shall be verified. Performance verific
40、ation isgenerally done by calibrating the equipment and measurementsystems according to established procedures.10. Calibration10.1 The borehole jack shall be calibrated before and at thecompletion of the program according to manufacturers orequivalent directions (7). In addition, the jack shall be c
41、ali-brated during the test program if the program consists of manytests or if the deformation readings become suspect. This isparticularly likely if the difference in the readings of near andfar LVDTs exceeds the manufacturers recommendation of 0.5mm (0.02 in.), indicating excessive misalignment of
42、theplatens.10.2 Calibration of the boreholes jack must be documented.Personnel calibrating the equipment must be qualified inadvance.11. Procedure11.1 Test each distinctive rock material in a borehole.11.2 Testing DiscontinuitiesLocate tests in both intactzones and fractured zones to evaluate the ef
43、fects of disconti-nuities. If the two LVDTs give significantly different displace-ment ($0.5 mm or 0.02 in.), discard the data and relocate thejack.FIG. 3 Marking Guide on Section of CasingD 4971 02 (2006)311.3 BoreholesBoreholes shall be free from dirt and drillcuttings. Wash the borehole with clea
44、n water if necessary.11.4 Initial Seating PressureWhen the jack is at the testlocation and in the desired orientation, raise the hydraulicpressure to 350 kPa (50 psi) to seat the platens against theborehole wall. Use this pressure as the “zero” pressurethroughout the remainder of the test.11.5 Press
45、ure LevelTest the rock to a pressure in excessof that required for full platen contact, but not exceeding thepressure or displacement capacity of the jack. Failure of therock may be recognized by an increase in the rate of deforma-tion without corresponding increase in the rate of pressure.11.6 Pres
46、sure CyclesIn at least 25 % of the tests in eachrock material, conduct multiple-pressure cycling to progres-sively higher loads to evaluate permanent deformation and theeffects of cycling on modulus. The peak pressure shall beapproximately 30, 60, and 100 % of the maximum. Duringeach cycle, vary the
47、 pressure in at least five equal incrementsand five decrements. At the end of each cycle, return thepressure to the initial seating pressure.11.7 Test at Various OrientationsIf tests are desired indifferent orientations, it is preferable to move the jack at least30.5 cm (12 in.) below or above the p
48、revious test location so asto provide an undisturbed site for testing. It is suggested thatsuccessive orientations be perpendicular to each other. It isrecommended that the first test be conducted at the deepestlocation, and the following tests be at successively shallowerdepths to prevent possible
49、borehole damage in a given testfrom interfering with subsequent testing.11.8 Indications of Time-Dependent EffectsDeterminetime dependent deformation characteristics during the test bymaintaining the maximum test pressure for 15 min andrecording deformation at 5 min intervals. When the pressure isreduced to the initial seating pressure, take deformation read-ings again at 5 min intervals for 15 min. If at least three suchdeterminations are made in a given rock material, and thedeformation indicated by either LVDT changing by more than5 % of th
