ASTM D4623-08
(Test Method)Standard Test Method for Determination of In Situ Stress in Rock Mass by Overcoring Method—USBM Borehole Deformation Gauge
Standard Test Method for Determination of In Situ Stress in Rock Mass by Overcoring Method<span class='unicode'>—</span>USBM Borehole Deformation Gauge
SIGNIFICANCE AND USE
Either virgin stresses or the stresses as influenced by an excavation may be determined. This test method is written assuming testing will be done from an underground opening; however, the same principles may be applied to testing in a rock outcrop at the surface.
This test method is generally performed at depths within 50 ft (15 m) of the working face because of drilling difficulties at greater depths. Some deeper testing has been done, but should be considered developmental. It is also useful for obtaining stress characteristics of existing concrete and rock structures for safety and modification investigations.
This test method is difficult in rock with fracture spacings of less than 5 in. (130 mm). A large number of tests may be required in order to obtain data.
The rock tested is assumed to be homogeneous and linearly elastic. The moduli of deformation and Poisson's ratio of the rock are required for data reduction. The preferred method for determining modulus of deformation values involves biaxially testing the recovered overcores, as described in Section 8. If this is not possible, values may be determined from uniaxial testing of smaller cores in accordance with Test Method D 7012. However, this generally decreases the accuracy of the stress determination in all but the most homogeneous rock. Results may be used from other in situ tests, such as Test Method D 4394 and Test Method D 4395.
The physical conditions present in three separate drill holes are assumed to prevail at one point in space to allow the three-dimensional stress field to be estimated. This assumption is difficult to verify, as rock material properties and the local stress field can vary significantly over short distances. Confidence in this assumption increases with careful selection of the test site.
Local geologic features with mechanical properties different from those of the surrounding rock can influence significantly the local stress field. In general, these features, if kno...
SCOPE
1.1 This test method covers the determination of the ambient local stresses in a rock mass and the equipment required to perform in situ stress tests using a three-component borehole deformation gauge (BDG). The test procedure and method of data reduction are described, including the theoretical basis and assumptions involved in the calculations. A section is included on troubleshooting equipment malfunctions.
Note 1—The gauge used in this test method is commonly referred to as a USBM gauge (U.S. Bureau of Mines three-component borehole deformation gauge).
1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety problems, 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: D4623 − 08
Standard Test Method for
Determination of In Situ Stress in Rock Mass by Overcoring
1
Method—USBM Borehole Deformation Gauge
This standard is issued under the fixed designation D4623; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D4395Test Method for Determining In Situ Modulus of
Deformation of Rock Mass Using Flexible Plate Loading
1.1 This test method covers the determination of the ambi-
Method
ent local stresses in a rock mass and the equipment required to
D6026Practice for Using Significant Digits in Geotechnical
perform in situ stress tests using a three-component borehole
Data
deformation gauge (BDG). The test procedure and method of
D7012Test Methods for Compressive Strength and Elastic
datareductionaredescribed,includingthetheoreticalbasisand
Moduli of Intact Rock Core Specimens under Varying
assumptions involved in the calculations.Asection is included
States of Stress and Temperatures
on troubleshooting equipment malfunctions.
3. Terminology
NOTE1—Thegaugeusedinthistestmethodiscommonlyreferredtoas
a USBM gauge (U.S. Bureau of Mines three-component borehole defor-
3.1 Definitions—See Terminology D653 for general defini-
2
mation gauge).
tions.
1.2 Thevaluesstatedininch-poundunitsaretoberegarded
3.2 Definitions:
asstandard.Nootherunitsofmeasurementareincludedinthis
3.2.1 deformation—displacement change in dimension of
standard.
the borehole due to changes in stress.
1.3 This standard does not purport to address all of the
3.2.2 in situ stress—the stress levels and orientations exist-
safety problems, if any, associated with its use. It is the
ing in the rock mass before excavation.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Method
bility of regulatory limitations prior to use.
4.1 Theovercoretestmeasuresthediametraldeformationof
a small-diameter borehole as it is removed from the surround-
2. Referenced Documents
ing stress field by coaxially coring a larger diameter hole.
3
2.1 ASTM Standards:
Deformation is measured across three diameters of the small
D653Terminology Relating to Soil, Rock, and Contained
hole, spaced 60° apart, using a deformation gauge developed
Fluids
by the U.S. Bureau of Mines. With knowledge of the rock
D3740Practice for Minimum Requirements for Agencies
deformation moduli, the measured borehole deformation can
Engaged in Testing and/or Inspection of Soil and Rock as
berelatedtothechangeinstressinaplaneperpendiculartothe
Used in Engineering Design and Construction
borehole. This change in stress is assumed to be numerically
D4394Test Method for Determining In Situ Modulus of
equal, although opposite in sense to the stresses existing in the
Deformation of Rock Mass Using Rigid Plate Loading
parent rock mass. Deformation measurements from three
Method
nonparallel boreholes, together with rock deformation moduli,
allow calculation of an estimate of the complete three-
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
dimensional state of stress in the rock mass.
Rock and is the direct responsibility of Subcommittee D18.12 on Rock Mechanics.
CurrenteditionapprovedJuly1,2008.PublishedJuly2008.Originallyapproved
5. Significance and Use
in 1986. Last previous edition approved in 2005 as D4623–05. DOI: 10.1520/
5.1 Either virgin stresses or the stresses as influenced by an
D4623-08.
2
Considerable information presented in this test method was taken from Bureau
excavation may be determined. This test method is written
of Mines Information Circular No. 8618, and Hooker, V.E., and Bickel, D.L.,
assuming testing will be done from an underground opening;
“Overcoring Equipment and Techniques Used in Rock Stress Determination,”
however, the same principles may be applied to testing in a
Denver Mining Research Center, Denver, CO, 1974.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or rock outcrop at the surface.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.2 Thistestmethodisgenerallyperformedatdepthswithin
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 50 ft (15 m) of the working face because of drilling difficulties
*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
1
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D4623 − 08
at greater depths. Some deeper testing has been done, but 5.8 Aminimum
...
This document is not anASTM standard and is intended only to provide the user of anASTM 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:D4623–05 Designation:D4623–08
Standard Test Method for
Determination of In Situ Stress in Rock Mass by Overcoring
1
Method—USBM Borehole Deformation Gauge
This standard is issued under the fixed designation D4623; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 Thistestmethodcoversthedeterminationoftheambientlocalstressesinarockmassandtheequipmentrequiredtoperform
in situ stress tests using a three-component borehole deformation gauge (BDG). The test procedure and method of data reduction
aredescribed,includingthetheoreticalbasisandassumptionsinvolvedinthecalculations.Asectionisincludedontroubleshooting
equipment malfunctions.
NOTE 1—ThegaugeusedinthistestmethodiscommonlyreferredtoasaUSBMgauge(U.S.BureauofMinesthree-componentboreholedeformation
2
gauge).
1.2The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for
information only.
1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this
standard.
1.3 This standard does not purport to address all of the safety problems, 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
3
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D3740 Practice for Minimum Requirements forAgencies Engaged in the Testing and/or Inspection of Soil and Rock as Used
in Engineering Design and Construction
D4394 TestMethodforDeterminingtheInSituModulusofDeformationofRockMassUsingtheRigidPlateLoadingMethod
D4395 Test Method for Determining the In Situ Modulus of Deformation of Rock Mass Using the Flexible Plate Loading
Method
D6026 Practice for Using Significant Digits in Geotechnical Data
D7012 Test Method for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of
Stress and Temperatures
3. Terminology
3.1 Definitions: See Terminology D653 for general definitions.
3.2 Definitions:
3.2.1 deformation—displacement change in dimension of the borehole due to changes in stress.
3.2.2 in situ stress—the stress levels and orientations existing in the rock mass before excavation.
4. Summary of Test Method
4.1 The overcore test measures the diametral deformation of a small-diameter borehole as it is removed from the surrounding
stress field by coaxially coring a larger diameter hole. Deformation is measured across three diameters of the small hole, spaced
60° apart, using a deformation gauge developed by the U.S. Bureau of Mines. With knowledge of the rock deformation moduli,
1
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 Nov.July 1, 2005.2008. Published November 2005.July 2008. Originally approved in 1986. Last previous edition approved in 20022005 as
D4623–025.
2
Considerableinformationpresentedinthistestmethodwastakenfrom Bureau of Mines Information Circular No. 8618,andHooker,V.E.,andBickel,D.L.,“Overcoring
Equipment and Techniques Used in Rock Stress Determination,” Denver Mining Research Center, Denver, CO, 1974.
3
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book ofASTM 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.
1
---------------------- Page: 1 ----------------------
D4623–08
the measured borehole deformation can be related to the change in stress in a plane perpendicular to the borehole. This change
in stress is assumed to be numerically equal, although opposite in sense to the stresses existing in the parent rock mass.
Deformation measurements from three nonparallel boreholes, together with rock deformation moduli, allow calculation of an
estimate of the complete three-dimensional state of stress in the rock mass.
5. Significance and Use
5.1 Eithervirginstressesorthes
...
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