ASTM D4971-02(2006)
(Test Method)Standard Test Method for Determining the In Situ Modulus of Deformation of Rock Using the Diametrically Loaded 76-mm (3-in.) Borehole Jack
Standard Test Method for Determining the In Situ Modulus of Deformation of Rock Using the Diametrically Loaded 76-mm (3-in.) Borehole Jack
SIGNIFICANCE AND USE
Results of this test method are used to predict displacements in rock mass caused by loads from a structure or from underground construction. It is one of several tests that should be performed.
Because the jack can apply directed loads, this test method can be performed to provide an estimate of anisotropy.
In theory, the analysis of test data is straight forward; the modulus estimate requires a record of applied hydraulic pressure versus borehole diameter change, and a knowledge of the rock’Poisson’ratio. In practice, the above procedure, using the original theoretical formula, frequently has resulted in computing a material modulus that was demonstrably too low.
For analyzing the test data it is assumed that the rock mass is linearly elastic, isotropic, and homogeneous. Within these assumptions, this test method can provide useful data for rock masses for which equivalent continuous properties can not be found or estimated.
Note 1—Notwithstanding the statements on precision and bias contained in this test method; the precision of this test method is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D 3740 are generally considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D 3740 does not in itself assure reliable testing. Reliable testing depends on many factors; Practice D 3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers the estimation of in situ modulus of a rock mass at various depths and orientations. Information on time-dependent deformation may also be obtained.
1.2 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D 6026.
1.2.1 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to the accuracy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this standard is beyond its scope.
1.3 The values stated in SI units are regarded as standard. The inch-pound units in parentheses are for information only.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D4971–02 (Reapproved 2006)
Standard Test Method for
Determining the In Situ Modulus of Deformation of Rock
Using the Diametrically Loaded 76-mm (3-in.) Borehole
Jack
This standard is issued under the fixed designation D 4971; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope* D 6032 Test Method for Determining Rock Quality Desig-
nation (RQD) of Rock Core
1.1 This test method covers the estimation of in situ
modulus of a rock mass at various depths and orientations.
3. Terminology
Information on time-dependent deformation may also be ob-
3.1 See Terminology D 653 for general definitions.
tained.
3.2 Definitions of Terms Specific to This Standard:
1.2 All observed and calculated values shall conform to the
3.2.1 deformation—change in shape or size, (see Terminol-
guidelines for significant digits and rounding established in
ogy D 653). In this test method deformation is the change in
Practice D 6026.
the diameter of the borehole.
1.2.1 The method used to specify how data are collected,
3.2.2 modulus of deformation—ratio of stress to strain for a
calculated, or recorded in this standard is not directly related to
material under given loading conditions; numerically equal to
theaccuracytowhichthedatacanbeappliedindesignorother
the slope of the tangent or the secant of the stress-strain curve.
uses, or both. How one applies the results obtained using this
The use of the term modulus of elasticity is recommended for
standard is beyond its scope.
materials that deform in accordance with Hooke’s law, and the
1.3 The values stated in SI units are regarded as standard.
term modulus of deformation is recommended for materials
The inch-pound units in parentheses are for information only.
that deform otherwise, (see Terminology D 653). In this test
1.4 This standard does not purport to address all of the
method, the modulus of deformation is calculated from the
safety concerns, if any, associated with its use. It is the
applied fluid pressure, the relative change in hole diameter, a
responsibility of the user of this standard to establish appro-
function of Poisson’s ratio, and a constant.
priate safety and health practices and determine the applica-
3.2.3 jack effıciency—ratio of the jack plate pressure to the
bility of regulatory limitations prior to use.
applied hydraulic pressure.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 The76mm(3.0in.)jacks,(seeFig.1andFig.2),induce
D 653 Terminology Relating to Soil, Rock, and Contained
undirectional pressure to the walls of a borehole by means of
Fluids
two opposed curved steel platens each covering a 90° sector,
D 3740 Practice for Minimum Requirements for Agencies
over a length of 20.3 cm (8 in.).
Engaged in the Testing and/or Inspection of Soil and Rock
4.2 Raw data from a test consist of hydraulic-line pressure,
as Used in Engineering Design and Construction
Q , versus readout from linear variable differential transform-
h
D 6026 Practice for Using Significant Digits in Geotechni-
ers (LVDT’s) measuring platen movement. Knowing the dis-
cal Data
placement calibration of the LVDT’s, the raw data can be
transformed to a test record of hydraulic pressure versus hole
diameter, D. For each increment of pressure, DQ , and hole
h
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
deformation, DD, theoretical data analysis (1), assuming rigid
Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
jack plates and full 90° contact, give the theoretical rock mass
Current edition approved May 1, 2006. Published June 2006. Originally
modulus, E (E ) as a function E=f (D Q ·DD· T*),
approved in 1989. Last previous edition approved in 2002 as D 4971–02. theoretical h
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to a list of references at the end of
the ASTM website. the standard.
*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.
D4971–02 (2006)
is measured on a linear segment of the loading curve, common
terminology is modulus of deformation. If E is measured on an
unloading linear segment, it is referred to as the recovery
modulus.
5. Significance and Use
5.1 Results of this test method are used to predict displace-
ments in rock mass caused by loads from a structure or from
underground construction. It is one of several tests that should
be performed.
5.2 Because the jack can apply directed loads, this test
method can be performed to provide an estimate of anisotropy.
5.3 Intheory,theanalysisoftestdataisstraightforward;the
modulus estimate requires a record of applied hydraulic
pressure versus borehole diameter change, and a knowledge of
the rock’s Poisson’s ratio. In practice, the above procedure,
using the original theoretical formula, frequently has resulted
in computing a material modulus that was demonstrably too
low.
5.4 For analyzing the test data it is assumed that the rock
mass is linearly elastic, isotropic, and homogeneous. Within
these assumptions, this test method can provide useful data for
rockmassesforwhichequivalentcontinuouspropertiescannot
be found or estimated.
NOTE 1—Notwithstanding the statements on precision and bias con-
tained in this test method; the precision of this test method is dependent
onthecompetenceofthepersonnelperformingit,andthesuitabilityofthe
equipment and facilities used. Agencies that meet the criteria of Practice
D 3740 are generally considered capable of competent and objective
testing. Users of this test method are cautioned that compliance with
Practice D 3740 does not in itself assure reliable testing. Reliable testing
depends on many factors; Practice D 3740 provides a means of evaluating
some of those factors.
6. Interferences
6.1 It is assumed that the tensile and compressive moduli of
the rock are equal and there is no tensile cracking induced in
the rock mass because of jack loading. If tensile cracks are
created at 90° to the loading direction, it has been shown (1)
FIG. 1 The 76-mm (3-in.) Borehole Jack
that the calculated modulus values can decrease by up to 29 %.
Therefore, tensile cracking would result in a decrease in the
slope of the loading curve and test data in the region of
decreased slope should not be used.
6.2 The volume of rock mass involved in the 76 mm (3.0
in.) diameter jack test has been estimated (2) to be about 0.15
3 3
m (5 ft ). This volume may not include enough discontinuities
to be representative of the rock mass on a larger scale.
6.3 Two aspects of jack behavior, discussed in 6.3.1 and
6.3.2, require careful consideration in the analysis of test data
and can be compensated for by the procedure outlined in this
test method and detailed by Heuze and Amadei (3).
6.3.1 The platen/rock contact may not cover 90° of the
borehole circumference, as assumed, because of radius mis-
match between the jack and the hole (4, 5).
FIG. 2 Schematic of Loading of the Borehole Jack
6.3.2 In rock with modulus of deformation greater than
about 7 GPa (10 psi), there is a longitudinal concave outward
where T* is a coefficient dependent upon Poisson’s ratio. If E bending of the jack platens that requires correction. This
D4971–02 (2006)
correction is necessary because the bending gives higher and perpendicular to the long axes of the columns in a basalt
displacements at the ends than at the center of the loading flow. Boreholes should generally be orthogonal to each other
platens and LVDT displacement gages are located near the and either parallel or perpendicular to the structure of the rock
ends of the platens. formation. At least ten tests in each rock material are recom-
mended.
7. Apparatus
8.3 Boreholes Reamed—It is recommended that a reaming
shellwithanominaloutsidediameterof76mm(3in.)beused.
7.1 Borehole Jack—The borehole jack for which equations
It is further recommended that a bit fabricated to reaming shell
and corrections are presented in Section 12 is the so-called
gage 76 mm (3 in.) also be used. This will minimize the radius
“hard rock” jack, that is currently manufactured under patent.
mismatch between the borehole and the jack. Accurate mea-
Themanufacturer’sspecificationsare:rangeoftravelis13mm
surement of the diameter of the borehole is important.
(0.5in.)fromclosedat70mm(2.75in.)tofullyopenat83mm
8.4 Boreholes Cored—The boreholes shall be drilled using
(3.25 in.), maximum pressure on borehole wall is 64 MPa
diamond core techniques; continuous core should be obtained.
(9300psi),anddeformationresolutionis0.025mm(0.001in.).
Oriented cores are desirable but not mandatory.
The maximum jack pressure is achieved with a hydraulic
8.5 Core Logged—The recovered core should be com-
system pressure of 69 MPa (10 000 psi). Deformation is
pletely logged, with emphasis on fractures and other mechani-
measured by an LVDT at each end of the loading platens.
cal inhomogeneties and water pressure. Rock quality designa-
These are referred to as the near and far LVDT respectively.
tion (RQD) should be calculated for each 1.5 m (5 ft) of hole
7.2 Pressure Gage—A hydraulic gage or electronic trans-
cored or core ru, in accordance with Test Method D 6032.
ducer may be used to measure the hydraulic system pressure.
8.6 Test Location—Withineachborehole,locationsforeach
The gage shall have an accuracy of at least 280 kPa (40 psi),
test should be selected based on the core logs. In some cases
including errors introduced by the readout equipment, and a
observation of the borehole with a borescope or borehole
resolution of at least 140 kPa (20 psi).
camera (film or television) may be useful.
7.3 Casing Alignment System—The borehole jack is at-
tached to 73 mm (2.875 in.) BX drill casing and placed into
9. Personnel and Equipment Requirements
position in the borehole. To determine the orientation of the
jack, an orientation mark is transferred to successive sections
9.1 Personnel—All personnel involved in performing the
of casing as they are added. To avoid introducing a systematic
test,includingtechniciansandtestsupervisors,shouldbeunder
and progressive error into orientation, an alignment device
the guidance of someone thoroughly familiar with the use of
shall be used to transfer the mark from one casing section to
the jack. Sometimes the personnel may be required to be
another. In vertical boreholes, a plumb line may be sufficient.
formally pre-qualified under a quality assurance (QA) proce-
Ininclinedorhorizontalboreholes,amarkingguidesuchasthe
dures established as part of the overall testing program.
one shown on Fig. 3 has been found satisfactory (6).
9.2 Equipment Performance Verification— The compliance
ofallequipmentandapparatuswithperformancespecifications
8. Sampling, Test Specimens, and Test Units
of this procedure shall be verified. Performance verification is
8.1 Number and Orientation of Boreholes—The number,
generally done by calibrating the equipment and measurement
spacing, and orientation of boreholes depend on the geometry systems according to established procedures.
of the project and the geology of the site.
8.2 Rock Sampling: 10. Calibration
8.2.1 Each type of rock should be tested. In addition, areas
10.1 The borehole jack shall be calibrated before and at the
of low modulus of deformation, such as fracture or alteration
completion of the program according to manufacturer’s or
zones within a rock mass, are of particular interest and should
equivalent directions (7). In addition, the jack shall be cali-
be tested.
brated during the test program if the program consists of many
8.2.2 Tests should be conducted at different orientations to
tests or if the deformation readings become suspect. This is
sample the anistropy of the rock mass, for example, parallel
particularly likely if the difference in the readings of near and
farLVDT’sexceedsthemanufacturer’srecommendationof0.5
mm (0.02 in.), indicating excessive misalignment of the
platens.
10.2 Calibration of the boreholes jack must be documented.
Personnel calibrating the equipment must be qualified in
advance.
11. Procedure
11.1 Test each distinctive rock material in a borehole.
11.2 Testing Discontinuities—Locate tests in both intact
zones and fractured zones to evaluate the effects of disconti-
nuities. If the two LVDT’s give significantly different displace-
ment ($0.5 mm or 0.02 in.), discard the data and relocate the
FIG. 3 Marking Guide on Section of Casing jack.
D4971–02 (2006)
11.3 Boreholes—Boreholes shall be free from dirt and drill
cuttings. Wash the borehole with clean water if necessary.
11.4 Initial Seating Pressure—When the jack is at the test
location and in the desired orientation, raise the hydraulic
pressure to 350 kPa (50 psi) to seat the platens against the
borehole wall. Use this pressure as the “zero” pressure
throughout the remainder of the test.
11.5 Pressure Level—Test the rock to a pressure in excess
of that required for full platen contact, but not exceeding the
pressure or displacement capacity of the jack. Failure of the
rock may be recognized by an increase in the rate of deforma-
tion without corresponding increase in the rate of pressure.
11.6 Pressure Cycles—In at least 25 % of the tests in each
rock material, conduct multiple-pressure cycling to progres-
sively higher loads to evaluate permanent deformation and the
effects of cycling on modulus. The peak pressure shall be
approximately 30, 60, and 100 % of the maximum. During
each cycle, vary the pressure in at least five equal increments
and five decrements. At the end of each cycle, return the
pressure to the initial seating pressure.
11.7 Test at Various Orientations—If tests are desired in
different orientations, it is preferable to move the jack at least
30.5cm(12in.)beloworabovetheprevioustestlocationsoas
to provide an undisturbed site for testing. It is suggested that
successive orientations be perpendicular to each other. It is
recommended that the first test be conducted at the deepest
location, and the following tests be at successively shallower
depths to prevent possible borehole damage in a given test
from interfering with subsequent testing.
11.8 Indications of
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.