ASTM D4971-16

Standard Test Method for Determining In Situ Modulus of Deformation of Rock Using Diametrically Loaded 76-mm (3-in.) Borehole Jack

SIGNIFICANCE AND USE
5.1 Results of this test method are used to predict displacements in rock mass caused by loads from a structure or from underground construction for the load range that the device can apply. 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 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'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 rock masses for which equivalent continuous properties cannot 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 D3740 are generally considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D3740 does not in itself assure reliable testing. Reliable testing depends on many factors; Practice D3740 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 This test method covers testing in an N size drill hole and is more relevant to a borehole jack device designed for “hard rock” than for soft rock.  
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
1.3.1 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.  
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard.  
1.5 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

• Status: Published
• Publication Date: 30-Nov-2016
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.12 - Rock Mechanics

Relations

• Replaces: ASTM D4971-08 - Standard Test Method for Determining In Situ Modulus of Deformation of Rock Using Diametrically Loaded 76-mm (3-in.) Borehole Jack
• Effective Date: 01-Dec-2016
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D3740-11 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Sep-2011
• Refers: ASTM D3740-10 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2010
• Refers: ASTM D653-09 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Jan-2009
• Refers: ASTM D653-08a - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Dec-2008
• Refers: ASTM D653-08 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Nov-2008
• Refers: ASTM D6032-08 - Standard Test Method for Determining Rock Quality Designation (RQD) of Rock Core
• Effective Date: 01-Jul-2008
• Refers: ASTM D3740-08 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2008
• Refers: ASTM D653-07f - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 15-Dec-2007

Overview

ASTM D4971-16 is the Standard Test Method for Determining In Situ Modulus of Deformation of Rock Using Diametrically Loaded 76-mm (3-in.) Borehole Jack. Developed by ASTM International, this standard provides guidelines for estimating the modulus of deformation of rock masses in their natural setting using a borehole jack device. By applying diametrically opposed loads through a hydraulically actuated jack in a 76-mm borehole, the method helps predict how rocks will deform under structural or underground construction loads. The results are used in engineering design to assess rock behavior, support design, and stability analysis, particularly for "hard rock" applications.

Key Topics

• Purpose and Scope

  • Designed to estimate the in situ modulus of deformation at various depths and orientations in hard rock.
  • Capable of providing data on time-dependent deformation.
  • Can assess rock anisotropy due to the ability to apply directed loads.

• Test Method Highlights

  • Utilizes a hydraulically operated borehole jack in an N size drill hole.
  • Deformation is monitored using linear variable differential transformers (LVDTs).
  • Test data are based on measurements of hydraulic pressure vs. borehole diameter change.
  • Assumes the rock mass is elastic, isotropic, and homogeneous for analysis.
  • Careful attention to calibration and alignment is essential for reliable results.

• Data Interpretation

  • Requires estimation of Poisson’s ratio and jack efficiency.
  • Analysis helps assess rock quality where equivalent continuous properties cannot be easily identified.
  • Effects of discontinuities, anisotropy, and time-dependent deformation are considered.

• Quality and Safety Considerations

  • Emphasizes the need for competent personnel and calibrated equipment.
  • Recommends compliance with ASTM D3740 for agency qualifications.
  • The test does not address all safety concerns; users must establish proper safety procedures.

Applications

• Site Investigation for Construction

  • Essential for the design and safety assessment of tunnels, foundations, dams, and underground caverns.
  • Provides engineers with realistic deformation parameters for structural calculations.

• Rock Mechanics and Geotechnical Engineering

  • Informs decisions on support measures and excavation methods.
  • Useful where laboratory core tests are insufficient due to scale or rock mass discontinuities.

• Assessment of Rock Mass Behavior

  • Helps predict deformations caused by imposed loads from structures or excavation.
  • Applied in both new projects and in situ monitoring of existing underground structures.

• Evaluation of Anisotropy and Discontinuities

  • Testing in various orientations allows for the assessment of directional variability in rock properties.
  • Provides targeted information on weak zones such as fractures or altered areas.

Related Standards

• ASTM D3740: Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock.
• ASTM D653: Terminology Relating to Soil, Rock, and Contained Fluids.
• ASTM D6026: Practice for Using Significant Digits in Geotechnical Data.
• ASTM D6032: Test Method for Determining Rock Quality Designation (RQD) of Rock Core.

Practical Value

Implementing ASTM D4971-16 ensures reliable, repeatable measurement of in situ deformation modulus, improving geotechnical design confidence and reducing engineering risks. Its application is particularly valuable in hard rock environments where standard laboratory tests may not capture field-scale behavior. By following this standardized method, engineering teams can achieve more accurate predictions of deformation and thus design safer, more cost-effective structures.

Keywords: in situ modulus, rock deformation, borehole jack test, ASTM D4971-16, hard rock, geotechnical engineering, anisotropy, site investigation, deformation modulus measurement, rock mechanics.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4971 − 16
Standard Test Method for
Determining In Situ Modulus of Deformation of Rock Using
Diametrically Loaded 76-mm (3-in.) Borehole Jack
This standard is issued under the fixed designation D4971; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* Used in Engineering Design and Construction
D6026 Practice for Using Significant Digits in Geotechnical
1.1 This test method covers the estimation of in situ
Data
modulus of a rock mass at various depths and orientations.
D6032 Test Method for Determining Rock Quality Designa-
Information on time-dependent deformation may also be ob-
tion (RQD) of Rock Core
tained.
3. Terminology
1.2 This test method covers testing in an N size drill hole
and is more relevant to a borehole jack device designed for
3.1 Definitions:
“hard rock” than for soft rock.
3.1.1 For definitions of common technical terms in this
standard, refer to Terminology D653.
1.3 All observed and calculated values shall conform to the
3.2 Definitions of Terms Specific to This Standard:
guidelines for significant digits and rounding established in
3.2.1 deformation, n—change in shape or size, (see Termi-
Practice D6026.
nology D653). In this test method deformation is the change in
1.3.1 The method used to specify how data are collected,
the diameter of the borehole.
calculated, or recorded in this standard is not directly related to
theaccuracytowhichthedatacanbeappliedindesignorother
3.2.2 modulus of deformation, n—ratio of stress to strain for
uses, or both. How one applies the results obtained using this
amaterialundergivenloadingconditions;numericallyequalto
standard is beyond its scope.
the slope of the tangent or the secant of the stress-strain curve.
3.2.2.1 Discussion—The use of the term modulus of elas-
1.4 The values stated in SI units are to be regarded as the
ticity is recommended for materials that deform in accordance
standard. The values given in parentheses are mathematical
with Hooke’s law, and the term modulus of deformation is
conversions to inch-pound units that are provided for informa-
recommended for materials that deform otherwise, (see Termi-
tion only and are not considered standard.
nology D653). In this test method, the modulus of deformation
1.5 This standard does not purport to address all of the
is calculated from the applied fluid pressure, the relative
safety concerns, if any, associated with its use. It is the
change in hole diameter, a function of Poisson’s ratio, and a
responsibility of the user of this standard to establish appro-
constant.
priate safety and health practices and determine the applica-
3.2.3 jack effıciency, n—ratio of the jack plate pressure to
bility of regulatory limitations prior to use.
the applied hydraulic pressure.
2. Referenced Documents
3.2.4 hard rock borehole jack, n—this refers to a specific
borehole jack by the manufacture that has platens designed for
2.1 ASTM Standards:
harder rocks, goes to higher pressures than a soft rock borehole
D653 Terminology Relating to Soil, Rock, and Contained
jack and whose displacement range is not exceeded at the
Fluids
maximum allowable pressure for the borehole jack.
D3740 Practice for Minimum Requirements for Agencies
Engaged in Testing and/or Inspection of Soil and Rock as
4. Summary of Test Method
4.1 The drill logs for a drill hole hole to be tested are
examined. Specific depths and orientations in the drill hole are
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
selected based upon the objectives of the test program.
Current edition approved Dec. 1, 2016. Published January 2017. Originally
4.2 The borehole jack in the fully retracted position is
approved in 1989. Last previous edition approved in 2008 as D4971 – 08. DOI:
10.1520/D4971-16.
positioned at each location selected in the drill hole for the test
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
program. The 76 mm (3 in.) jacks, (see Fig. 1 and Fig. 2),
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
induce unidirectional pressure to the walls of a borehole by
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. means of two opposed curved steel platens each covering a 90°
*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 − 16
deformation data is collected. Testing is usually done from the
deepest test zone in the drill hole and then tested at subsequent
shallower test intervals to minimize risks to the borehole jack.
4.3 Raw data from a test consist of hydraulic-line pressure,
Q , versus readout from linear variable differential transform-
h
ers (LVDT’s) measuring platen movement. Knowing the dis-
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, ∆Q , and hole
h
deformation,∆D, theoretical data analysis (1), assuming rigid
jack plates and full 90° contact, give the theoretical rock mass
modulus, E (E ) as a function E=f (∆ Q ·∆D· T*),
theoretical h
where T* is a coefficient dependent upon Poisson’s ratio. If E
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
undergroundconstructionfortheloadrangethatthedevicecan
apply. 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
rock masses for which equivalent continuous properties cannot
be found or estimated.
FIG. 1 The 76-mm (3-in.) Borehole Jack: Assemble (a) and Disas-
sembled (b)
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
D3740 are generally considered capable of competent and objective
testing. Users of this test method are cautioned that compliance with
Practice D3740 does not in itself assure reliable testing. Reliable testing
depends on many factors; Practice D3740 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)
that the calculated modulus values can decrease by up to 29 %.
Therefore, tensile cracking would result in a decrease in the
FIG. 2 Schematic of Diametrical Loading of the Borehole Wall by
the Borehole Jack Platens
The boldface numbers in parentheses refer to a list of references at the end of
sector, over a length of 20 cm (8 in.) and pressure versus the standard.
D4971 − 16
in more hostile and remote field conditions than it high be for a more
slope of the loading curve and test data in the region of
sophisticated system.
decreased slope should not be used.
7.4 Casing Alignment System—The borehole jack is at-
6.2 The volume of rock mass involved in the 76 mm (3.0
tached to 73 mm (2.875 in.) BX drill casing and placed into
in.) diameter jack test has been estimated (2) to be about 0.15
position in the borehole. To determine the orientation of the
3 3
m (5 ft ).This volume may not include enough discontinuities
jack, an orientation mark is transferred to successive sections
to be representative of the rock mass on a larger scale.
of casing as they are added. To avoid introducing a systematic
6.3 Two aspects of jack behavior, discussed in 6.3.1 and
and progressive error into orientation, an alignment device
6.3.2, require careful consideration in the analysis of test data
shall be used to transfer the mark from one casing section to
and can be compensated for by the procedure outlined in this
another. In vertical boreholes, a plumb line may be sufficient.
test method and detailed by Heuze and Amadei (3).
Ininclinedorhorizontalboreholes,amarkingguidesuchasthe
6.3.1 The platen/rock contact may not cover 90° of the
one shown on Fig. 3 has been found satisfactory (6).
borehole circumference, as assumed, because of radius mis-
match between the jack platens and the interior wall of the drill
8. Sampling, Test Specimens, and Test Units
hole (4, 5).
8.1 Number and Orientation of Boreholes—The number,
6.3.2 In rock with modulus of deformation greater than
spacing, and orientation of boreholes depend on the geometry
about 7 GPa (10 psi), there is a longitudinal concave outward
of the project and the geology of the site.
bending of the jack platens that requires correction. This
8.2 Rock Sampling:
correction is necessary because the bending gives higher
8.2.1 Each type of rock should be tested. In addition, areas
displacements at the ends than at the center of the loading
of low modulus of deformation, such as fracture or alteration
platens and the displacement gauges are located near the ends
zones within a rock mass, are of particular interest and should
of the platens.
be tested.
6.4 Any effects on the data from the in situ stress field
8.2.2 Tests should be conducted at different orientations to
around the borehole wall may need to be considered.
sample the anistropy of the rock mass, for example, parallel
and perpendicular to the long axes of the columns in a basalt
7. Apparatus
flow. Boreholes should generally be orthogonal to each other
and either parallel or perpendicular to the structure of the rock
7.1 Borehole Jack—The borehole jack (Fig. 1) for which
formation. At least ten tests in each rock material are recom-
equations and corrections are presented in Section 12 is the
mended.
so-called “hard rock” jack, that is currently manufactured
under a patent.Ahydraulic hose and electrical cable extending
8.3 Boreholes Reamed—It is recommended that a reaming
from the borehole jack up the borehole to the surface and is
shellwithanominaloutsidediameterof76mm(3in.)beused.
connected to a readout unit or units for reading displacement
It is further recommended that a bit fabricated to reaming shell
and to hydraulic pressure system that is used to apply and
gauge76mm(3in.)alsobeused.Thiswillminimizetheradius
measure the hydraulic pressure applied to the jack. The
mismatch between the borehole and the jack. Accurate mea-
manufacturer’sspecificationsare:rangeoftravelis10mm(0.5
surement of the diameter of the borehole is important.
in.) from closed at 70 mm (2.75 in.) to fully open at 80 mm
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—Therecoveredcoreshouldbecompletely
system pressure of 69 MPa (10 000 psi). Deformation is
logged, with emphasis on fractures and other mechanical
measured by an LVDT at each end of the loading platens.
inhomogeneties and water pressure. Rock quality designation
These are referred to as the near and far LVDT respectively.
7.2 Pressure Gauge—Ahydraulic gauge or electronic trans-
ducer may be used to measure the hydraulic system pressure to
the platens. The gauge or transducer shall have an accuracy of
at least 280 kPa (40 psi), including errors introduced by the
readoutequipment,andaresolutionofatleast140kPa(20psi)
and a range of at least 69 MPa (10 000 psi).
7.3 Displacement Recorder—An electronic readout box is
used to record the displacement measured by each LVDT
associated with the platens. The readout boxes used shall have
an accuracy of at least 0.025 mm (0.001 in.) and able to read
arangeoftravelof10mm(0.5in.)fromclosedat70mm(2.75
in.) to full open at 80 mm (3.25 in.).
NOTE 2—A more sophisticated data acquisition system may be used
than what is discussed in 7.2 and 7.3. The data acquisition equipment
mentioned is sufficient and is usually more robust in the field; especially FIG. 3 Marking Guide on Section of Casing
D4971 − 16
(RQD) should be calculated for each 1.5 m (5 ft) of hole cored rock may be recognized by an increase in the rate of deforma-
or core run, in accordance with Test Method D6032. tion without corresponding increase in the rate of pressure.
8.6 Test Location—Within each borehole, locations for each 11.7 Pressure Cycles—In at least 25 % of the tests in each
test should be selected based on the core logs. In some cases rock material, conduct multiple-pressure cycling to progres-
observation of the borehole with a borescope or borehole sively higher loads to evaluate permanent deformation and the
camera (film or television) may be useful. effects of cycling on modulus. The peak pressure shall be
approximately 30, 60, and 100 % of the maximum. During
9. Personnel and Equipment Requirements each cycle, vary the pressure in at least five equal increments
and five decrements. At the end of each cycle, return the
9.1 Personnel—All personnel involved in performing the
pressure to the initial seating pressure.
test,includingtechniciansandtestsupervisors,shouldbeunder
the guidance of someone thoroughly familiar with the use of 11.8 Test at Various Orientations—If tests are desired in
the jack. Sometimes the personnel may be required to be different orientations, it is preferable to move the jack at least
formally pre-qualified under a quality assurance (QA) proce- 30.5cm(12in.)beloworabovetheprevioustestlocationsoas
to provide an undisturbed site for testing. It is suggested that
dures established as part of the overall testing program.
successive orientations be perpendicular to each other.
9.2 Equipment Performance Verification— The compliance
11.9 Indications of Time-Dependent Effects—Determine
ofallequipmentandapparatuswithperformancespecifications
of this procedure shall be
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4971 − 08 D4971 − 16
Standard Test Method for
Determining In Situ Modulus of Deformation of Rock Using
Diametrically Loaded 76-mm (3-in.) Borehole Jack
This standard is issued under the fixed designation D4971; 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 (´) indicates an editorial change since the last revision or reapproval.
1. 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 This test method covers testing in an N size drill hole and is more relevant to a borehole jack device designed for “hard rock”
than for soft rock.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026.
1.3.1 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.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical
conversions to inch-pound units that are provided for information only and are not considered standard.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D6026 Practice for Using Significant Digits in Geotechnical Data
D6032 Test Method for Determining Rock Quality Designation (RQD) of Rock Core
3. Terminology
3.1 See Terminology D653 for general definitions.
3.1 Definitions:
3.1.1 For definitions of common technical terms in this standard, refer to Terminology D653.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 deformation—deformation, n—change in shape or size, (see Terminology D653). In this test method deformation is the
change in the diameter of the borehole.
3.2.2 modulus of deformation—deformation, n—ratio of stress to strain for a material under given loading conditions;
numerically equal to the slope of the tangent or the secant of the stress-strain curve. The use of the term modulus of elasticity is
recommended for materials that deform in accordance with Hooke’s law, and the term modulus of deformation is recommended
for materials that deform otherwise, (see Terminology D653). In this test method, the modulus of deformation is calculated from
the applied fluid pressure, the relative change in hole diameter, a function of Poisson’s ratio, and a constant.
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
Current edition approved July 1, 2008Dec. 1, 2016. Published July 2008January 2017. Originally approved in 1989. Last previous edition approved in 20062008 as
D4971 – 02D4971 – 08. (2006). DOI: 10.1520/D4971-08.10.1520/D4971-16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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 − 16
3.2.2.1 Discussion—
The use of the term modulus of elasticity is recommended for materials that deform in accordance with Hooke’s law, and the term
modulus of deformation is recommended for materials that deform otherwise, (see Terminology D653). In this test method, the
modulus of deformation is calculated from the applied fluid pressure, the relative change in hole diameter, a function of Poisson’s
ratio, and a constant.
3.2.3 jack effıciency—effıciency, n—ratio of the jack plate pressure to the applied hydraulic pressure.
3.2.4 hard rock borehole jack, n—this refers to a specific borehole jack by the manufacture that has platens designed for harder
rocks, goes to higher pressures than a soft rock borehole jack and whose displacement range is not exceeded at the maximum
allowable pressure for the borehole jack.
4. Summary of Test Method
4.1 The drill logs for a drill hole hole to be tested are examined. Specific depths and orientations in the drill hole are selected
based upon the objectives of the test program.
4.2 The 76 mm (3.0borehole jack in the fully retracted position is positioned at each location selected in the drill hole for the
test program. The 76 mm (3 in.) jacks, (see Fig. 1 and Fig. 2), induce undirectionalunidirectional pressure to the walls of a borehole
by means of two opposed curved steel platens each covering a 90° sector, over a length of 20.3 cm (8 in.).20 cm (8 in.) and pressure
FIG. 1 The 76-mm (3-in.) Borehole JackJack: Assemble (a) and Disassembled (b)
D4971 − 16
FIG. 2 Schematic of Diametrical Loading of the Borehole JackWall by the Borehole Jack Platens
versus deformation data is collected. Testing is usually done from the deepest test zone in the drill hole and then tested at
subsequent shallower test intervals to minimize risks to the borehole jack.
4.3 Raw data from a test consist of hydraulic-line pressure, Q , versus readout from linear variable differential transformers
h
(LVDT’s) measuring platen movement. Knowing the displacement 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, ΔQ , and hole deformation, ΔD,
h
theoretical data analysis (1), assuming rigid jack plates and full 90° contact, give the theoretical rock mass modulus, E (E )
theoretical
as a function E = f (Δ Q ·ΔD· T*), where T* is a coefficient dependent upon Poisson’s ratio. If E is measured on a linear segment
h
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 displacements in rock mass caused by loads from a structure or from
underground construction. construction for the load range that the device can apply. 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 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’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 rock masses for which equivalent continuous properties can not cannot
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 D3740 are
generally considered capable of competent and objective testing. Users of this test method are cautioned that compliance with Practice D3740 does not
in itself assure reliable testing. Reliable testing depends on many factors; Practice D3740 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) 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 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 mismatch
between the jack platens and the interior wall of the drill hole (4, 5).
The boldface numbers in parentheses refer to a list of references at the end of the standard.
D4971 − 16
6.3.2 In rock with modulus of deformation greater than about 7 GPa (10 psi), there is a longitudinal concave outward bending
of the jack platens that requires correction. This correction is necessary because the bending gives higher displacements at the ends
than at the center of the loading platens and LVDTthe displacement gauges are located near the ends of the platens.
6.4 Any effects on the data from the in situ stress field around the borehole wall may need to be considered.
7. Apparatus
7.1 Borehole Jack—The borehole jack (Fig. 1) for which equations and corrections are presented in Section 12 is the so-called
“hard rock” jack, that is currently manufactured under patent. a patent. A hydraulic hose and electrical cable extending from the
borehole jack up the borehole to the surface and is connected to a readout unit or units for reading displacement and to hydraulic
pressure system that is used to apply and measure the hydraulic pressure applied to the jack. The manufacturer’s specifications are:
range of travel is 1310 mm (0.5 in.) from closed at 70 mm (2.75 in.) to fully open at 8380 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 hydraulic system pressure of 69 MPa (10 000 psi). Deformation is measured by an LVDT at each end of the loading platens.
These are referred to as the near and far LVDT respectively.
7.2 Pressure Gauge—A hydraulic gauge or electronic transducer may be used to measure the hydraulic system pressure.
pressure to the platens. The gauge or transducer shall have an accuracy of at least 280 kPa (40 psi), including errors introduced
by the readout equipment, and a resolution of at least 140 kPa (20 psi) and a range of at least 69 MPa (10 000 psi).
7.3 Displacement Recorder—An electronic readout box is used to record the displacement measured by each LVDT associated
with the platens. The readout boxes used shall have an accuracy of at least 0.025 mm (0.001 in.) and able to read a range of travel
of 10 mm (0.5 in.) from closed at 70 mm (2.75 in.) to full open at 80 mm (3.25 in.).
NOTE 2—A more sophisticated data acquisition system may be used than what is discussed in 7.2 and 7.3. The data acquisition equipment mentioned
is sufficient and is usually more robust in the field; especially in more hostile and remote field conditions than it high be for a more sophisticated system.
7.4 Casing Alignment System—The borehole jack is attached to 73 mm (2.875 in.) BX drill casing and placed into position in
the borehole. To determine the orientation of the jack, an orientation mark is transferred to successive sections of casing as they
are added. To avoid introducing a systematic and progressive error into orientation, an alignment device shall be used to transfer
the mark from one casing section to another. In vertical boreholes, a plumb line may be sufficient. In inclined or horizontal
boreholes, a marking guide such as the one shown on Fig. 3 has been found satisfactory (6).
8. Sampling, Test Specimens, and Test Units
8.1 Number and Orientation of Boreholes—The number, spacing, and orientation of boreholes depend on the geometry of the
project and the geology of the site.
8.2 Rock Sampling:
8.2.1 Each type of rock should be tested. In addition, areas of low modulus of deformation, such as fracture or alteration zones
within a rock mass, are of particular interest and should be tested.
8.2.2 Tests should be conducted at different orientations to sample the anistropy of the rock mass, for example, parallel and
perpendicular to the long axes of the columns in a basalt flow. Boreholes should generally be orthogonal to each other and either
parallel or perpendicular to the structure of the rock formation. At least ten tests in each rock material are recommended.
8.3 Boreholes Reamed—It is recommended that a reaming shell with a nominal outside diameter of 76 mm (3 in.) be used. It
is further recommended that a bit fabricated to reaming shell gauge 76 mm (3 in.) also be used. This will minimize the radius
mismatch between the borehole and the jack. Accurate measurement of the diameter of the borehole is important.
FIG. 3 Marking Guide on Section of Casing
D4971 − 16
8.4 Boreholes Cored—The boreholes shall be drilled using diamond core techniques; continuous core should be obtained.
Oriented cores are desirable but not mandatory.
8.5 Core Logged—The recovered core should be completely logged, with emphasis on fractures and other mechanical
inhomogeneties and water pressure. Rock quality designation (RQD) should be calculated for each 1.5 m (5 ft) of hole cored or
core run, in accordance with Test Method D6032.
8.6 Test Location—Within each borehole, locations for each test should be selected based on the core logs. In some cases
observation of the borehole with a borescope or borehole camera (film or television) may be useful.
9. Personnel and Equipment Requirements
9.1 Personnel—All personnel involved in performing the test, including technicians and test supervisors, should be under the
guidance of someone thoroughly familiar with the use of the jack. Sometimes the personnel may be required to be formally
pre-qualified under a quality assurance (QA) procedures established as part of the overall testing program.
9.2 Equipment Performance Verification— The compliance of all equipment and apparatus with performance specifications of
this procedure shall be verified. Performance verification is generally done by calibrating the equipment and measurement systems
according to established procedures.
10. Calibration
10.1 The borehole jack shall be calibrated before and at the completion of the program according to manufacturer’s or
equivalent directions (7). In addition, the jack shall be calibrated during the test program if the program consists of many tests or
if the deformation readings become suspect. This is particularly likely if the difference in the readings of near and far LVDT’s
exceeds the manufacturer’s recommendation of 0.5 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 a
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