ASTM D5607-02(2006)
(Test Method)Standard Test Method for Performing Laboratory Direct Shear Strength Tests of Rock Specimens Under Constant Normal Force
Standard Test Method for Performing Laboratory Direct Shear Strength Tests of Rock Specimens Under Constant Normal Force
SCOPE
1.1 This test method establishes requirements and laboratory procedures for performing direct shear strength tests on rock specimens. It includes procedures for both intact rock strength and sliding friction tests which can be performed on specimens that are homogeneous, or have planes of weakness, including natural or artificial discontinuities. Examples of an artificial discontinuity include a rock-concrete interface or a lift line from a concrete pour. Discontinuities may be open, partially or completely healed or filled (that is, clay fillings and gouge). Only one discontinuity per specimen can be tested. The test is usually conducted in the undrained state with an applied constant normal load. However, a clean, open discontinuity may be free draining, and, therefore, a test on a clean, open discontinuity could be considered a drained test. During the test, shear strength is determined at various applied stresses normal to the sheared plane and at various shear displacements. Relationships derived from the test data include shear strength versus normal stress and shear stress versus shear displacement (shear stiffness). The term "normal force" is used in the title instead of normal stress because of the indefinable area of contact and the minimal relative displacement between upper and lower halves of the specimen during testing. The actual contact areas during testing change, but the actual total contact surface is unmeasurable. Therefore nominal area is used for loading purposes and calculations. Note 1
Since this test method makes no provision for the measurement of pore pressures, the strength values determined are expressed in terms of total stress, uncorrected for pore pressure.
1.2 This standard applies to hard rock, soft rock, and concrete.
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.
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Designation: D 5607 – 02 (Reapproved 2006)
Standard Test Method for
Performing Laboratory Direct Shear Strength Tests of Rock
Specimens Under Constant Normal Force
This standard is issued under the fixed designation D 5607; 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* 2. Referenced Documents
1.1 This test method establishes requirements and labora- 2.1 ASTM Standards:
tory procedures for performing direct shear strength tests on D 653 Terminology Relating to Soil, Rock, and Contained
rock specimens. It includes procedures for both intact rock Fluids
strength and sliding friction tests which can be performed on D 2216 Test Methods for Laboratory Determination of Wa-
specimens that are homogeneous, or have planes of weakness, ter (Moisture) Content of Soil and Rock by Mass
including natural or artificial discontinuities. Examples of an D 3740 Practice for Minimum Requirements for Agencies
artificialdiscontinuityincludearock-concreteinterfaceoralift Engaged in the Testing and/or Inspection of Soil and Rock
line from a concrete pour. Discontinuities may be open, as Used in Engineering Design and Construction
partially or completely healed or filled (that is, clay fillings and E4 Practices for Force Verification of Testing Machines
gouge).Onlyonediscontinuityperspecimencanbetested.The E 122 Practice for Calculating Sample Size to Estimate,
test is usually conducted in the undrained state with an applied With a Specified Tolerable Error, the Average for a
constant normal load. However, a clean, open discontinuity Characteristic of a Lot or Process
may be free draining, and, therefore, a test on a clean, open
3. Terminology
discontinuity could be considered a drained test. During the
test, shear strength is determined at various applied stresses 3.1 For common definitions of terms used in this standard,
refer to Terminology D 653.
normaltotheshearedplaneandatvarioussheardisplacements.
Relationships derived from the test data include shear strength 3.2 Definitions of Terms Specific to This Standard:
3.2.1 apparent stress—nominal stress, that is, external load
versusnormalstressandshearstressversussheardisplacement
per unit area. It is calculated by dividing the externally applied
(shear stiffness).
load by the nominal area.
NOTE 1—The term “normal force” is used in the title instead of normal
3.2.2 Asperity:
stress because of the indefinable area of contact and the minimal relative
3.2.2.1 quality—the roughness of a surface.
displacement between upper and lower halves of the specimen during
3.2.2.2 feature—asurfaceirregularityrangingfromsharpor
testing. The actual contact areas during testing change, but the actual total
contact surface is unmeasurable. Therefore nominal area is used for
angular to rounded or wavy.
loading purposes and calculations.
3.2.2.3 asperities—the collection of a surface’s irregulari-
NOTE 2—Since this test method makes no provision for the measure-
ties that account for the surface’s roughness.
ment of pore pressures, the strength values determined are expressed in
3.2.3 Discontinuity:
terms of total stress, uncorrected for pore pressure.
3.2.3.1 An abrupt change, interruption, or break in the
1.2 This standard applies to hard rock, soft rock, and
integrity or physical properties of rock, such as a bedding
concrete.
plane, fracture, cleavage, crack, joint, or fault.
1.3 This standard does not purport to address all of the
3.2.3.2 A gapped discontinuity consists of opposing rock
safety concerns, if any, associated with its use. It is the
surfaces separated by an open or filled space. A tight discon-
responsibility of the user of this standard to establish appro-
tinuity consists of opposing rock surfaces in intimate and
priate safety and health practices and determine the applica-
generally continuous contact; it may be valid to treat such a
bility of regulatory limitations prior to use.
discontinuity as a single surface.
1 2
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved May 1, 2006. Published June 2006. Originally
Standards volume information, refer to the standard’s Document Summary page on
approved in 1994. Last previous edition approved in 2002 as D 5607 – 02. 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.
D 5607 – 02 (2006)
3.2.3.3 A discontinuity’s opposing rock surfaces may be asperities, and rotations at or wedging of the asperities. Sliding
planar to nonplanar and matching to misfit. on and shearing of the asperities can occur simultaneously.
3.2.4 intact shear strength—the peak shear resistance (in When the normal force is not sufficient to restrain dilation, the
units of stress) of an intact rock specimen or of a specimen shear mechanism consists of the overriding of the asperities.
containing a completely healed discontinuity. When the normal load is large enough to completely restrain
3.2.5 nominal area—area obtained by measuring or calcu- dilation,theshearmechanismconsistsoftheshearingoffofthe
lating the cross-sectional area of the shear plane. It is calcu- asperities.
lated after its relevant cross-sectional dimensions are deter- 5.3 Usingthistestmethodtodeterminetheshearstrengthof
mined. an intact specimen may generate overturning moments which
3.2.6 residual shear strength—the shear stress, (see Fig. 1), could result in an inclined shear break.
corresponding to a specific normal stress, for which the shear 5.4 Shear strength is influenced by the overburden or
stress remains essentially constant with increasing shear dis- normal pressure; therefore, the larger the overburden pressure,
placement. In most cases, the shear stress after reaching Point the larger the shear strength.
A is the residual shear strength. 5.5 Insomecases,itmaybedesirabletoconducttestsinsitu
3.2.7 shear stiffness—represents the resistance of the speci- rather than in the laboratory to determine the representative
men to shear displacements under an applied shear force prior shear strength of the rock mass, particularly when design is
to reaching the peak shear strength. It is calculated by dividing controlled by discontinuities filled with very weak material.
the applied apparent shear stress by the resulting shear dis-
NOTE 3—The quality of the result produced by this standard is
placement (slope of the curve prior to peak shear strength, Fig.
dependent on the competence of the personnel performing it, and the
1).
suitability of the equipment and facilities used. AGencies that meet the
3.2.8 sliding friction shear strength—the peak shear resis- criteria of Practice D 3740 are generally considered capable of competent
and objective testing/sampling/inspection and the like. Users of this
tance (in units of stress) of a rock specimen containing an open
standard are cautioned that compliance with Practice D 3740 does not in
discontinuity.
itself assure reliable results. Reliable results depend on many factors,
Practice D 3740 provides a means of evaluating some of those factors.
4. Summary of Test Method
4.1 While maintaining a constant force normal to the
6. Apparatus
nominal shear plane of the specimen, an increasing external
6.1 Testing Machine—Loading device, to apply and register
shear force is applied along the designated shear plane to cause
normal and shear forces on the specimens. It must have
shear displacement. The applied normal and shear forces and
adequate capability to apply the shear force at a rate conform-
the corresponding normal and shear displacements are mea-
ing to the specified requirements. It shall be verified at suitable
sured and recorded. These data are the basis for calculating the
time intervals in accordance with the procedures given in
required parameters.
Practices E4, and comply with the requirements prescribed
therein. The resultant of the shear force passes through the
5. Significance and Use
center of the intended shear zone or the centroid of the shear
5.1 Determinationofshearstrengthofarockspecimenisan
plane surface area to minimize adverse moments.
importantaspectinthedesignofstructuressuchasrockslopes,
NOTE 4—There are many different direct shear device designs. Al-
dam foundations, tunnels, shafts, waste repositories, caverns
though details may vary concerning how to encapsulate specimens into
for storage, and other purposes. Pervasive discontinuities
shear boxes as well as details for assembling the machine, the determi-
(joints, bedding planes, shear zones, fault zones, schistocity) in
nations are usually similar.
a rock mass, and genesis, crystallography, texture, fabric, and
6.2 Fig. 2 is a schematic of an example shear box, an
other factors can cause the rock mass to behave as an
integral part of the machine.
anisotropic and heterogeneous discontinuum. Therefore, the
6.3 Pressure-Maintaining Device—A hydraulic component
precise prediction of rock mass behavior is difficult.
that will hold a pressure, within specified tolerances, within the
5.2 For nonplanar joints or discontinuities, shear strength is
hydraulic system.
derived from a combination base material friction and overrid-
6.4 Specimen Holding Rings—Aluminum or steel holding
ing of asperities (dilatancy), shearing or breaking of the
rings (see Fig. 3) with internal dimensions sufficient to accom-
modate specimens mounted in an encapsulating medium.
6.5 Spacer Plates:
6.5.1 Split Spacer Plates—Plastic (or other suitable mate-
rial) plates of varying thicknesses for isolating an intact
specimen’s shear zone from the encapsulating compound (see
Fig. 3).
6.5.2 Non-split Spacer Plates—Plastic (or other suitable
material) plates of varying thicknesses that have a circular or
oval hole in the center and are used for non-intact specimens.
6.6 Displacement Measuring Device— Linear variable dif-
ferential transformers (LVDTs) may be used as normal and
FIG. 1 Generalized Shear Stress and Shear Displacement Curve shear displacement measuring devices. Other devices such as
D 5607 – 02 (2006)
FIG. 2 Schematic Test Setup—Direct Shear Box with Encapsulated Specimen
4 ), filler or modelling clay, calipers, spatula, circular clamps,
Barton, N., and Choubey, V., The Shear Strength of Rock Joints in Theory and
Practice, Rock Mechanics, 10, 1977.
NOTE 1—Note the split plastic plates for isolating the shear zone.
FIG. 3 View Showing Pouring Encapsulating Material Around
Upper Half of Specimen
dial indicators and DCDTs, are satisfactory. Four devices are
used to measure the normal displacement and provide a check
on specimen rotation about an axis parallel to the shear zone
and perpendicular to the shearing direction. Another device
measures the shear displacement. These displacement devices
should have adequate ranges of travel to accommodate the
displacements, 613 mm (60.5 in.). Sensitivities of these
devices should be 0.025 mm (0.001 in.) for shear displacement
and 0.0025 mm (0.0001 in.) for normal displacement. Ensure
that the devices are located away from the loading direction so
as not to be damaged in sudden failures.
6.7 Data Acquisition Equipment—Acomputer may be used
to control the test, collect data, and plot results.
7. Reagents and Materials
7.1 Miscellaneous Items—Carpenter’s contour gage for
measuring joint surface roughness, roughness chart (see Fig.
FIG. 4 Roughness Profiles and Corresponding JRC Values
Associated With Each One
D 5607 – 02 (2006)
utility knife, towels, markers, plotting papers, encapsulating cross-sectional area of the intact specimen is calculated. For
compound, and camera. inclined core the apparent area can be determined by measur-
ing the diameter and angle of tip u.
8. Test Specimens
10.2.1.2 Cross-Sectional Area of Nongeometrical Shapes—
The outline of the cross-sectional area of the specimen or shear
8.1 Sampling:
8.1.1 Intact Specimen—Care should be exercised in core plane is traced on paper and the area measured with a
planimeter.
drilling, handling, and sawing the samples to minimize me-
chanical damage to test specimens. No liquids other than water
10.2.1.3 Joint Roughness of a Clean Discontinuity—Before
should be in contact with a test specimen. and after testing, a carpenter contour gage is used to measure
joint roughness in the direction of anticipated shear displace-
NOTE 5—To obtain relevant parameters for the design, construction, or
ment.When all the prongs of the gage are lowered on a flat and
maintenance of major engineering structures, test specimens should be
hard surface, the tips of the prongs will fall on a straight line.
representative of the host properties as nearly as practicable.
Place this straight line pronged gage onto the shear plane and
8.1.2 Specimen with a Single Discontinuity—Rock samples
lower all the prongs to make contact with the shear surface.
are collected and shipped using methods that minimize distur-
Remove the gage. The tips of the gage trace the shear plane
bance of test zones.Aspecimen’s dimensions and the location
surface along the line of shearing. Trace the tips of the prongs
of a discontinuity to be tested should allow sufficient clearance
onto paper, and compare this tracing to match with one of the
for adequate encapsulation. The in situ integrity of disconti-
lines on Fig. 4; then, select and record the corresponding joint
nuities in a sample is to be maintained from the time of
roughness coefficient.
sampling until the discontinuity is tested.Tape, plastic wrap, or
10.2.1.4 Joint Roughness for Partially or Fully Healed
other means may be utilized to preserve the in situ moisture
Discontinuity—After failure occurs in a shear test, contour
content along the test zone. Plastic half rounds, core boxes,
gages and the standard roughness chart are used to determine
freezing, or other methods may be utilized to bridge the
the joint roughness coefficient.
discontinuities and prevent differential movement from occur-
10.2.1.5 Take before and after test photographs of each
ring along the discontinuity. This is especially important for
specimen.
discontinuities containing any soft, or weak material.
10.2.2 Encapsulation:
8.2 Size and Shape—The he
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