ASTM D7401-08
(Test Method)Standard Test Methods for Laboratory Determination of Rock Anchor Capacities by Pull and Drop Tests (Withdrawn 2017)
Standard Test Methods for Laboratory Determination of Rock Anchor Capacities by Pull and Drop Tests (Withdrawn 2017)
SIGNIFICANCE AND USE
For a support system to be fully effective, the support system must be able to contain the movement of rock material due to excavation stress release, slabbing, etc. Data from the load tests are used by engineers to design the appropriate support system to improve safety and stability of underground support systems. Test Methods D 4435 and D 4436 are used for in-situ load tests.
The local characteristics of the rock, such as roughness and induced fractures, are significant factors in the anchor strength. The material used to simulate the borehole surface should be sufficiently roughened so that failure occurs in the rock anchor and not at the simulated anchor-rock surface. In the case of steel pipe, internal threading using different spacing and depth is accomplished using a machinist’s lathe to simulate roughness.
Note 1—The quality of the result produced by this standard 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/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D 3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D 3740 provides a means of evaluating some of these factors.
SCOPE
1.1 These test methods cover the quantitative determination of the working and ultimate static or dynamic capacities of full scale rock anchors. Dynamic capacities are determined to simulate rockburst and blasting conditions (1). The rock anchors are installed in steel pipe to simulate standard boreholes sizes. Rock anchor capacities are determined as a function of resin to steel bolt bond strength and steel bolt yield strength. These tests are not intended to determine rock anchor to borehole rock surface shear strength.
1.2 These test methods are applicable to mechanical, resin, or other similar anchor systems.
1.3 Two methods are provided to determine the capacities of rock anchors, as follows:
1.3.1 Method A—Using a horizontal hydraulically loaded pull test system.
1.3.2 Method B—Using a vertical dynamically loaded drop test system.
1.4 The values stated in SI units are to be regarded as the standard. No other units of measurement are included in this standard.
1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D 6026.
1.6 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.
WITHDRAWN RATIONALE
These test methods cover the quantitative determination of the working and ultimate static or dynamic capacities of full scale rock anchors. Dynamic capacities are determined to simulate rockburst and blasting conditions The rock anchors are installed in steel pipe to simulate standard boreholes sizes. Rock anchor capacities are determined as a function of resin to steel bolt bond strength and steel bolt yield strength. These tests are not intended to determine rock anchor to borehole rock surface shear strength.
Formerly under the jurisdiction of Committee D18 on Soil and Rock, these test methods were withdrawn in January 2017 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
General Information
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: D7401 − 08
Standard Test Methods for
Laboratory Determination of Rock Anchor Capacities by Pull
and Drop Tests
This standard is issued under the fixed designation D7401; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 These test methods cover the quantitative determination
D653 Terminology Relating to Soil, Rock, and Contained
of the working and ultimate static or dynamic capacities of full
Fluids
scale rock anchors. Dynamic capacities are determined to
D3740 Practice for Minimum Requirements for Agencies
simulate rockburst and blasting conditions (1). The rock
Engaged in Testing and/or Inspection of Soil and Rock as
anchors are installed in steel pipe to simulate standard bore-
Used in Engineering Design and Construction
holes sizes. Rock anchor capacities are determined as a
D4435 Test Method for Rock Bolt Anchor Pull Test
function of resin to steel bolt bond strength and steel bolt yield
D4436 Test Method for Rock Bolt Long-Term Load Reten-
strength. These tests are not intended to determine rock anchor
tion Test
to borehole rock surface shear strength.
D6026 Practice for Using Significant Digits in Geotechnical
1.2 These test methods are applicable to mechanical, resin,
Data
or other similar anchor systems.
3. Terminology
1.3 Twomethodsareprovidedtodeterminethecapacitiesof
3.1 Definitions—Refer to Terminology D653 for specific
rock anchors, as follows:
definitions.
1.3.1 Method A—Using a horizontal hydraulically loaded
pull test system.
3.2 Definitions of Terms Specific to This Standard:
1.3.2 Method B—Using a vertical dynamically loaded drop
3.2.1 linescan camera—a camera with high optical linear
test system.
resolutionthatcapturestwo-dimensionalimagesbymovingthe
object perpendicularly to the scan line.
1.4 The values stated in SI units are to be regarded as the
3.2.2 maximum load—represents the highest load value
standard. No other units of measurement are included in this
recorded during the test.
standard.
3.2.3 rock anchor—usually constructed of steel, which is
1.5 All observed and calculated values shall conform to the
inserted into pre-drilled holes in rock and secured with a fixing
guidelines for significant digits and rounding established in
agent for the purpose of ground control.
Practice D6026.
3.2.4 RPM—acronym for revolutions per minute.
1.6 This standard does not purport to address all of the
3.2.5 transverse stiffness—theabilityoftheboreholeorsteel
safety concerns, if any, associated with its use. It is the
tube wall to deform radially.
responsibility of the user of this standard to establish appro-
3.2.6 yield load—corresponds to the onset of plastic defor-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. mation.
4. Summary of Test Methods
4.1 A rock anchor is installed in a steel pipe instead of a
These test methods are under the jurisdiction ofASTM Committee D18 on Soil
borehole the same manner and in the same material as its
and Rock and are the direct responsibility of Subcommittee D18.12 on Rock
Mechanics.
Current edition approved Jan. 1, 2008. Published February 2008. DOI: 10.1520/ For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D7401-08. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
The boldface numbers in parentheses refer to a list of references at the end of Standards volume information, refer to the standard’s Document Summary page on
this standard. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7401 − 08
intended use (2). In the Pull test, the rock anchor is hydrauli- 6.1.3 Boreholes are simulated by 12 mm-thick cold rolled
cally pulled horizontally and the displacement of the bolt head steel tubes of the required internal diameter. The steel tube
is measured concurrently. The bolt is pulled until the anchor preparation includes a slight roughening of the inside surface
system fails (or to the ultimate stroke of the ram). The ultimate over approximately the last meter. This roughened section is
and working capacity of the rock anchor is calculated from the
referredtoasthetopofthetube.Twosetsof25.4mmholesare
plot of load versus displacement. In the Drop test, a known drilled near the top of the tube. The top set supports the tube in
mass is released vertically impacting on a plate at a preset
the drop test apparatus and the lower holes allow access to the
distance that is in turn affixed to the end of a rock anchor. The end of the rock anchor after installation. For each rock anchor,
maximum energy is expressed in kJ.
two holes are drilled through the top end of the rock anchor to
allow the clevis to be attached during testing.
5. Significance and Use
6.2 Method A—Pull Test System (Static):
5.1 For a support system to be fully effective, the support
6.2.1 A double acting hollow hydraulic ram, with a mini-
system must be able to contain the movement of rock material
mum load capacity of 325 kN and displacement of 150 mm is
due to excavation stress release, slabbing, etc. Data from the
recommended for this test. Displacement positioning of the
load tests are used by engineers to design the appropriate
ram is accomplished using a hand operated pump. A hand
support system to improve safety and stability of underground
pump is used during the controlled loading. Once the rock
support systems. Test Methods D4435 and D4436 are used for
anchor or the resin starts to fail, an electric pump (Px) can be
in-situ load tests.
used until the specimen fails or the ram reaches its stroke
5.2 The local characteristics of the rock, such as roughness
capacity. Fig. 1 displays a typical pull test set-up.
and induced fractures, are significant factors in the anchor
6.2.2 The ram hydraulic pressure is monitored using an
strength. The material used to simulate the borehole surface
electronic pressure transducer. Two 25.4 mm stroke potenti-
should be sufficiently roughened so that failure occurs in the
ometers with a resolution of 0.6 mm are recommended for
rock anchor and not at the simulated anchor-rock surface. In
displacement measurements. The potentiometers measure the
the case of steel pipe, internal threading using different spacing
plateandtheenddisplacementsduringthetest.Allinstruments
anddepthisaccomplishedusingamachinist’slathetosimulate
are connected to a data acquisition system.
roughness.
NOTE 1—The quality of the result produced by this standard is
6.3 Method B—Drop Test System (Dynamic):
dependent on the competence of the personnel performing it, and the
6.3.1 The drop or dynamic test system (Fig. 2) shall
suitability of the equipment and facilities used. Agencies that meet the
criteria of Practice D3740 are generally considered capable of competent accommodate a height of drop of the mass of at least 2.0 m
and objective testing/sampling/inspection/etc. Users of this standard are
below the coupler pin. The mass capacity of 1 ton, (1T) shall
cautioned that compliance with Practice D3740 does not in itself assure
not be less than 325 kN. As the energy input is controlled by
reliable results. Reliable results depend on many factors; Practice D3740
the drop height and the mass, the maximum energy available
provides a means of evaluating some of these factors.
and the maximum impact velocity that each drop can reach are
6. Apparatus
62 kJoules and 6.5 m/s, respectively.
6.1 Components Common to Both Test Methods: 6.3.2 Instrumentation used to measure the loads and the
6.1.1 The manufacturer provides the rock anchors, plates, displacements are measured at the plate and at the end of the
nuts, domes, washers, bottom plate, resins, and steel tubes for rock anchor. Displacements in some systems are measured
the tests. The manufacturer specifies the borehole size, type of using linescan cameras. The cameras are sampled at 10 000
lines per second to match the sampling of the analog signals.
resin, penetration rate and rotation rate for the installation of
the rock anchor and any other installation information. The lines are amalgamated to form an image of distance versus
time. The location of black and white targets attached to the
6.1.2 Upon receipt, the rock anchor measurements include
length, rod diameter, length and diameter of the threaded part, plate nut or to the bolt end, is detected within the image. This
length and diameter of the mixing element and any specific system measures loads using arrays of four piezoelectric force
characteristics. sensors, sandwiched between two platen rings.
FIG. 1 Schematic of Pull Test System
D7401 − 08
FIG. 2 Schematic of Drop Test System
6.3.3 All instruments are connected to a data acquisition 7.1.4 Prior to installation, slide the rock anchor specimen
system. The impact duration is typically 60 ms, but data are completely into the tube.
recorded for about 1.5 s before and up to 5 s after the impact 7.1.5 Mark the collar position and orientation of the mixing
to ensure that all instruments have stabilized.
element on the rock anchor specimen. These lines are used
during installation to ensure that the rock anchor is fully
7. Procedure
inserted and to identify the paddle orientation.
7.1.6 Thread the two nuts completely onto the rock anchor
7.1 Encapsulated Resin Anchor Bolt Specimen Installation:
7.1.1 Insert into the tube (see Fig. 3), a plug, which extends and tighten them in order to seat the drill chuck.
7.1.7 Remove the rock anchor and slide the resin cartridges
from the top of the specimen tube to below the second set of
25.4 mm holes. This prevents the end of the rock anchor and are into the end of the tube.
the resin from being installed past this point. 7.1.8 Insert the rock anchor into the chuck, which is
7.1.2 Insert additional plugs into the bottom set of holes to attached to a drill mounted on a sliding rail with an indepen-
prevent resin from escaping during installation. dent advance drive system.
7.1.3 Place the specimen tube in a jig to align it with the 7.1.9 Spin the rock anchor into the tube at a steady
drill. advancement and constant RPM rate.
FIG. 3 Schematic of Installation System
D7401 − 08
7.1.10 Once the rock anchor reaches the plug, stop the the tube in place. The 25.4 mm bolt has a small hole through
advance and rotate the rock anchor for an additional 5 seconds. its middle to allow for the passage of the clevis to the end of
7.1.11 Remove the drill and rotate the lines, indicating the the rock anchor.
mixing element orientation, to the horizontal. 7.3.6 Lower the clevis onto the end of the rock anchor.
7.1.12 Remove the tube from the jig, and remove all the
7.3.7 Use two machine screws to attach the clevis to the
plugs.
cone.
7.1.13 Remove any resin beyond the end through the holes
7.3.8 Lower the magnet on to the mass.
in the tube.
7.3.9 Lift the mass with the overhead crane hoists.
7.1.14 Clean the mixing element and the end of the rock
7.3.10 Install the 12 mm-thick impact plate, the rock anchor
anchor, including its two small holes.
plate, the dome washer and the threaded nut on the threaded
7.1.15 An electric motor (1 hp), capable of generating 150
end of the cone bolt.
to400RPM,isusedtosimulatethemechanized(thatis,bolter)
7.3.11 Install the target under the threaded nut, for the lower
installation. The installation set-ups are tightly controlled in
linescan camera.
order to improve the mixing and to minimize the differences in
7.3.12 Calibrate the lights and the two linescan cameras
mixing quality between specimens. The set-ups can be readily
(lower and upper).
adjusted to provide the penetration rate and rotational speed
7.3.13 Lower the mass onto the impact plate.
required.
7.3.14 Move the crane hoists from the mass to the magnet.
7.2 Method A—Pull Test:
7.3.15 Start the data acquisition system.
7.2.1 Attacha1m long high yield strength wire (piano
7.3.16 Lift the mass magnetized to the electromagnet to the
wire) to the end of the rock anchor, and feed the wire out the
desired height. The electromagnet is lifted with the pair of
top of the tube.
synchronized cranes mounted on the top of the machine.
7.2.2 Reinstallthetubeintheinstallationjigandconnectthe
7.3.17 Cut the power to the magnet, to free fall the mass
piano wire to a potentiometer.
onto the specimen.
7.2.3 Install the 300 mm diameter–12 mm thick steel plate,
7.3.18 Acquire data from the plate and end displacement
150 mm stroke 325 kN hollow ram and the heavy washer over
monitors.
the end of the rock anchor up against the tube. Thread on the
7.3.19 Acquiredatafromtheloadcellsattachedtotheframe
nut on and tighten the entire assembly.
above the specimen and below the plate. Use a suitable frame
7.2.4 Attach the second potentiometer to the nut.
load cell such as an array of four piezoelectric force sensors
7.2.5 Use the potentiometers to measure the plate and the
sandwiched between two platen rings. Locate sensors on top of
end displacements during the test.
the frame crossbeams. Locate another set of piezoelectric
7.2.6 Use both a hand pump and an electric pump to power
sensors on the threaded part of the bolt just below the plate.
thehollowram.Usethehandpumpduringthetestpriortorock
7.3.20 Use linescan cameras to acquire displacements at
anchor failure.
10 000 lines per second to match the sampling of the analog
7.2.7 Once the rock anchor or the resin starts to fail, use the
signals.Thelocationofablackandwhitetarget,attachedtothe
electric pump until the specimen fails or the ram reaches its
plate nut or to the end, is detected within the image. Linescan
stroke capacity.
camera lines are amalgamated to form an image of distance
7.3 Method B—Drop Test:
versus time.
7.3.1 Set-up the predetermined mass to be dropped.
7.3.21 Drops could be repeated until the rock anchor fails or
7.3.2 Install the clevis on the end of a thin-walled tube that
until the appropriate cumulative amount of energy desired is
runs up through the center of the support assembly for the
reached.
specimen tube. The clevis connects the thin-walled tube to the
7.4 Post Test Inspection:
end of the rock anchor.
7.4.1 Mechanically cut specimens open lengthwise after
7.3.3 Measure the end displacement with a linescan camera,
testing is completed.
which monitors a target on the thin-walled tube.
7.4.2 Compare the actual end displacement to the test
7.3.4
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