ASTM D4553-90(1995)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4553 – 90 (Reapproved 1995)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Determining In Situ Creep Characteristics of Rock
This standard is issued under the fixed designation D 4553; 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 pad, or rock in response to and in the same direction as the
applied load.
1.1 This test method covers the preparation, equipment, test
3.1.3 load—total force acting on the rock face.
procedure, and data documentation for determining in situ
3.1.4 rigid plate—plate with a deflection of less than 0.0005
creep characteristics of a rock mass using a rigid plate
in. (0.0125 mm) from the center to the edge of the plate when
subjected to controlled loading.
maximum load is applied.
1.2 This test method is designed to be conducted in an
underground opening; however, with suitable modifications,
4. Summary of Test Method
this test could be conducted at the surface.
4.1 Areas on two opposing faces of a test opening are
1.3 The test is usually conducted parallel or perpendicular to
flattened, smoothed, and made parallel.
the anticipated axis of thrust, as dictated by the design load or
4.2 A grout pad and rigid metal plate are installed against
other orientations, based upon the application.
each face and a hydraulic loading system is placed between the
1.4 Flexible plate apparatus can be used if the anticipated
rigid plates.
creep displacement is within the tolerance of the travel of the
4.3 The two faces are rapidly loaded to the desired creep
flat jacks.
load, without shock, the load maintained, and the displacement
1.5 The values stated in inch-pound units are to be regarded
of the plate measured as a function of time.
as the standard.
1.6 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 Results of this test method are used to predict time-
responsibility of the user of this standard to establish appro-
dependent deformation characteristics of a rock mass resulting
priate safety and health practices and determine the applica-
from loading. It is a test that may be required depending on
bility of regulatory limitations prior to use. For specific
rock type or anticipated loads, or both.
precaution statements, see Section 8.
5.2 This test method may be useful in structural design
analysis where loading is applied over an extensive period.
2. Referenced Documents
5.3 This test method is normally performed at ambient
2.1 ASTM Standards:
temperature, but equipment can be modified or substituted for
D 4394 Test Method for Determining the In Situ Modulus
operations at other temperatures.
of Deformation of Rock Mass Using the Rigid Plate
2 5.4 Results of this test method may be useful in verifying
Loading Method
2 laboratory creep data and structural mathematical modeling
D 4403 Practice for Extensometers Used in Rock
analyses.
3. Terminology 5.5 Creep characteristics are determined under a nonuni-
form state of stress.
3.1 Definitions of Terms Specific to This Standard:
5.6 If during a field investigation, time-dependent charac-
3.1.1 creep—a time-dependent displacement of a plate
teristics are detected, then an in situ creep test shall be
pushed into the surface of the rock by a constant normal load.
performed.
It is not directly related with laboratory creep data because of
the nonuniformity of stress within the rock mass underneath
6. Interferences
the plate.
6.1 A completely inflexible plate used to load the rock face
3.1.2 displacement—movement of the rigid plate, grout
is difficult to construct. However, if the plate is constructed as
rigid as feasible, the rock face is smoothed, and a thin,
This test method is under the jurisdiction of ASTM Committee D-18 on Soil high-modulus material is used for the pad, the error in the
and Rock and is the direct responsibility of Subcommittee D18.12 on Rock
measured displacements will be minimal.
Mechanics.
6.2 The rock under the loaded area is generally not homo-
Current edition approved May 25, 1990. Published July 1990. Originally
geneous, as assumed in theory. The rock will respond to the
published as D 4553 – 85. Last previous edition D 4553 – 85.
Annual Book of ASTM Standards, Vol 04.08.
D 4553
load according to its local deformational characteristics and mance verification is generally done by calibrating the equip-
orientation of discontinuities. The use of the average plate ment and measurement system (see Fig. 2).
displacement will mitigate this problem. If this creep test is 8.2 Enforce safety by applicable safety standards. Pressure
performed immediately after a plate loading test, the results of lines must be bled of air to preclude violent failure of the
the creep test will be different than if it had been performed on pressure system.
virgin rock.
9. In Situ Conditions
7. Apparatus
9.1 Areas that are geologically representative of the mass
7.1 Surface Preparation Equipment—Test-site preparation shall be selected. The plates shall be contained in the same
equipment should include an assortment of excavation tools, geologic member. The testing program shall be designed so
such as drills and chipping hammers. Blasting shall not be that effects of local geology can be clearly distinguished and
allowed during final preparation of the test site. the impact of excavation minimized.
7.2 Instrumentation: 9.2 The size of the bearing plate will be determined by the
7.2.1 Displacement Measuring Equipment—For displace- local geology, pressures to be applied, and the size of the
ment measurements, dial gages or linear variable differential opening in which the test is to be performed. These parameters
transformers (LVDTs) are generally used. A sensitivity of at shall be considered prior to excavation of the opening. Opti-
least 60.0001 in. (0.0025 mm), including the error of the mum opening dimensions are approximately six times the plate
readout equipment, and an accuracy of at least 0.0005 in. diameter. Recommended plate diameter is commonly 1|n$ to
(0.0125 mm) are required. Errors in excess of 0.0004 in. (0.01 3|n@ ft (0.5 to 1 m). Other plate sizes may be used depending
mm) can invalidate test results when the modulus of rock mass upon site specifics.
6 4
exceeds 5 3 10 psi (3.5 3 10 MPa). 9.3 The effects of anisotropy shall be investigated by
7.2.2 Load Cell—A load cell is recommended to measure appropriately oriented tests; for example, parallel and perpen-
the load on the bearing plate. An accuracy of 61000 lbf (4.4 dicular to the long axes of columns in a basalt flow.
kN) or 65 % of maximum test load, including errors intro- 9.4 Tests shall be performed at a site not affected by
duced by the readout system, and a sensitivity of at least 500 structural changes resulting from excavations of the opening.
lbf (2.2 kN) are reasonable. Long-term stability of the instru- The zone of rock that contributes to the measured displacement
mentation system shall be verified throughout the test. during loading depends on the diameter of the plate and the
7.3 Loading Equipment: applied load. Larger plates and higher loads measure the
7.3.1 Hydraulic Ram or Flat Jacks—This equipment, ca- response of rock farther away from the test opening. Thus, if
pable of applying and maintaining desired pressures to the rock around the opening is damaged by the excavation
within6 3 %, is usually used to apply the load. A spherical process and the creep properties of the damaged zone are the
bearing of suitable capacity shall be coupled to one of the primary objective of the test program, small-diameter plate
bearing plates. If a hydraulic ram is used, the load shall be tests on typically excavated surfaces are adequate.
corrected to account for the effects of ram friction. If flat jacks 9.5 Site conditions may dictate that site preparation and pad
are used, the jacks shall not be expanded beyond a thickness construction be performed immediately after excavation.
equal to3%ofthe diameter of a metal jack.
10. Procedure
7.3.2 The loading equipment includes a device for applying
10.1 A schematic of an optimum test setup is shown in Fig.
the load and the reaction members, usually thick-walled
3. A properly located platform (not shown) allows for align-
aluminum or steel pipes, to transmit the load.
ment of all test components.
7.3.3 Load Maintaining Equipment—Equipment such as a
10.2 Conduct the test across a “diameter” or chord of the
servo-control system or air over hydraulic oil is required.
opening with the two test surfaces nearly parallel and in planes
7.3.4 Bearing Pads—The bearing pads shall have a modu-
6 4
oriented perpendicular to the thrust of the loading assembly.
lus of elasticity of at least 4 3 10 psi (3 3 10 MPa) (30 GPa)
10.3 Surface Preparation:
and shall be capable of conforming to the rock surface and
10.3.1 Method—Prepare the surface by a method that
bearing plate. High early strength grout or molten sulfur
causes minimal damage to the finished rock surface. In the
bearing pads are recommended.
initial preparation of the finished test surface, many short drill
7.3.5 Bearing Plates—The bearing plates shall approximate
holes may be required to remove unsound rock. Any residual
a rigid die as closely as practical. A bearing plate that has been
found satisfactory is shown in Fig. 1. Although the exact design rock between the drill holes may be removed by burnishing or
moving the bit back and forth until a smooth face is achieved.
and materials may differ, the stiffness of the bearing plate shall
be at least the minimum stiffness necessary to produce no Alternatively, in hard, competent rock, controlled blasting with
very small charges may be required to remove the unwanted
measurable deflection of the plate under maximum load.
materials. In weaker materials, coarse grinding or cutting
8. Precautions
devices may be used.
8.1 All equipment and apparatus shall comply with the 10.3.2 Size—The prepared rock surface shall extend at least
performance specifications in Section 7 and apparatus shall be one-half the diameter of the bearing plate beyond the edge of
verified. If no requirements are stated in Section 7, the the plate.
manufacturer’s specifications for the equipment may be appro- 10.3.3 Rock Quality—To the extent possible, prepare the
priate as a guide to assure acceptable performance. Perfor- bearing surface in sound rock. Remove loose and broken rock
D 4553
FIG. 1 Rigid Bearing Plate for 12 in. Diameter Test
from the ex
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