ASTM D7400-08
(Test Method)Standard Test Methods for Downhole Seismic Testing
Standard Test Methods for Downhole Seismic Testing
SIGNIFICANCE AND USE
The seismic downhole method provides a designer with information pertinent to the seismic wave velocities of the materials in question (1). The P-wave and S-wave velocities are directly related to the important geotechnical elastic constants of Poisson’s ratio, shear modulus, bulk modulus, and Young’s modulus. Accurate in-situ P-wave and S-wave velocity profiles are essential in geotechnical foundation designs. These parameters are used in both analyses of soil behavior under both static and dynamic loads where the elastic constants are input variables into the models defining the different states of deformations such as elastic, elasto-plastic, and failure. Another important use of estimated shear wave velocities in geotechnical design is in the liquefaction assessment of soils.
A fundamental assumption inherent in the test methods is that a laterally homogeneous medium is being characterized. In a laterally homogeneous medium the source wave train trajectories adhere to Snell’s law of refraction. Another assumption inherent in the test methods is that the stratigraphic medium to be characterized can have transverse isotropy. Transverse isotropy is a particularly simple form of anisotropy because velocities only vary with vertical incidence angle and not with azimuth. By placing and actuating the seismic source at offsets rotated 90° in plan view, it may be possible to evaluate the transverse anisotropy of the medium.
Note 1—The quality of the results produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities. 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 those factors.
SCOPE
1.1 These test methods are limited to the determination of the interval velocities from arrival times and relative arrival times of compression (P) and vertically (SV) and horizontally (SH) polarized shear (S) seismic waves which are generated near surface and travel down to an array of vertically installed seismic sensors. A preferred method intended to obtain data for use on critical projects where the highest quality data is required is included. Also included is an optional method intended for use on projects which do not require measurements of a high degree of precision.
1.2 Various applications of the data will be addressed and acceptable procedures and equipment, such as seismic sources, receivers, and recording systems will be discussed. Other items addressed include source-to-receiver spacing, drilling, casing, grouting, a procedure for borehole installation, and conducting actual borehole and seismic cone tests. Data reduction and interpretation is limited to the identification of various seismic wave types, apparent velocity relation to true velocity, example computations, use of Snell's law of refraction, and assumptions.
1.3 There are several acceptable devices that can be used to generate a high-quality P or SV source wave or both and SH source waves. Several types of commercially available receivers and recording systems can also be used to conduct an acceptable downhole survey. Special consideration should be given to the types of receivers used and their configuration. Heavily-damped sensors should not be used so that spectral smearing, phase shifting, and latency response between sensors is avoided. These test methods primarily concern the actual test procedure, data interpretation, and specifications for equipment which will yield uniform test results.
1.4 All recorded and calculated values shall conform to the guide for significant digits and rounding established in Practice D 6026.
1.4.1 The proced...
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Designation: D7400 − 08
StandardTest Methods for
1
Downhole Seismic Testing
This standard is issued under the fixed designation D7400; 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* 1.4.1 Theproceduresusedtospecifyhowdataarecollected/
recorded and calculated in these test methods are regarded as
1.1 These test methods are limited to the determination of
theindustrystandard.Inaddition,theyarerepresentativeofthe
the interval velocities from arrival times and relative arrival
significant digits that should generally be retained. The proce-
times of compression (P) and vertically (SV) and horizontally
dures used do not consider material variation, purpose for
(SH) polarized shear (S) seismic waves which are generated
obtaining the data, special purpose studies, or any consider-
near surface and travel down to an array of vertically installed
ations for the user’s objectives; and it is common practice to
seismicsensors.Apreferredmethodintendedtoobtaindatafor
increase or reduce significant digits of reported data to be
use on critical projects where the highest quality data is
commensuratewiththeseconsiderations.Itisbeyondthescope
required is included. Also included is an optional method
of these test methods to consider significant digits used in
intended for use on projects which do not require measure-
analysis methods for engineering design.
ments of a high degree of precision.
1.4.2 Measurements made to more significant digits or
1.2 Various applications of the data will be addressed and
better sensitivity than specified in these test methods shall not
acceptable procedures and equipment, such as seismic sources,
be regarded a nonconformance with this standard.
receivers,andrecordingsystemswillbediscussed.Otheritems
1.5 This standard is written using SI units. Inch-pound units
addressed include source-to-receiver spacing, drilling, casing,
grouting, a procedure for borehole installation, and conducting are provided for convenience. The values stated in inch pound
units may not be exact equivalents; therefore, they shall be
actual borehole and seismic cone tests. Data reduction and
interpretation is limited to the identification of various seismic used independently of the SI system. Combining values from
the two systems may result in nonconformance with this
wavetypes,apparentvelocityrelationtotruevelocity,example
computations, use of Snell’s law of refraction, and assump- standard.
tions. 1.5.1 The gravitational system of inch-pound units is used
when dealing with inch-pound units. In this system, the pound
1.3 There are several acceptable devices that can be used to
(lbf) represents a unit of force (weight), while the unit for mass
generate a high-quality P or SV source wave or both and SH
isslugs.Therationalizedslugunitisnotgiven,unlessdynamic
source waves. Several types of commercially available receiv-
(F = ma) calculations are involved.
ers and recording systems can also be used to conduct an
1.5.2 It is common practice in the engineering/construction
acceptable downhole survey. Special consideration should be
profession to concurrently use pounds to represent both a unit
given to the types of receivers used and their configuration.
of mass (lbm) and of force (lbf). This implicitly combines two
Heavily-damped sensors should not be used so that spectral
separate systems of units; that is, the absolute system and the
smearing,phaseshifting,andlatencyresponsebetweensensors
gravitational system. It is scientifically undesirable to combine
isavoided.Thesetestmethodsprimarilyconcerntheactualtest
the use of two separate sets of inch-pound units within a single
procedure,datainterpretation,andspecificationsforequipment
standard. As stated, this standard includes the gravitational
which will yield uniform test results.
system of inch-pound units and does not use/present the slug
1.4 All recorded and calculated values shall conform to the
unit for mass. However, the use of balances or scales recording
guideforsignificantdigitsandroundingestablishedinPractice
3
pounds of mass (lbm) or recording density in lbm/ft shall not
D6026.
be regarded as nonconformance with this standard.
1
1.6 This standard does not purport to address all of the
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.09 on Cyclic and
safety concerns, if any, associated with its use. It is the
Dynamic Properties of Soils.
responsibility of the user of this standard to establish appro-
CurrenteditionapprovedJune1,2008.PublishedJuly2008.Originallyapproved
priate safet
...
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:D7400–07 Designation:D7400–08
Standard Test Methods for
1
Downhole Seismic Testing
This standard is issued under the fixed designation D 7400; 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 These test methods are limited to the determination of the interval velocities from arrival times and relative arrival times
of compression (P)(P) and vertically (SV) and horizontally (SH) polarized shear (S)(S) seismic waves which are generated near
surface and travel down to an array of vertically installed seismic sensors. A preferred method intended to obtain data for use on
critical projects where the highest quality data is required is included. Also included is an optional method intended for use on
projects which do not require measurements of a high degree of precision.
1.2 Various applications of the data will be addressed and acceptable procedures and equipment, such as seismic sources,
receivers, and recording systems will be discussed. Other items addressed include source-to-receiver spacing, drilling, casing,
grouting, a procedure for borehole installation, and conducting actual borehole and seismic cone actual test conduct.tests. Data
reductionandinterpretationislimitedtotheidentificationofvariousseismicwavetypes,apparentvelocityrelationtotruevelocity,
example computations, use of Snell’s law of refraction, and assumptions.
1.3 There are several acceptable devices that can be used to generate a high-quality Por SVsource wave or both and SH source
waves. Several types of commercially available receivers and recording systems can also be used to conduct an acceptable
downhole survey. Special consideration should be given to the types of receivers used and their configuration. Heavily-damped
sensors should not be used so that spectral smearing, phase shifting, and latency response between sensors is avoided. These test
methods primarily concern the actual test procedure, data interpretation, and specifications for equipment which will yield uniform
test results.
1.4 All recorded and calculated values shall conform to the guide for significant digits and rounding established in Practice
D 6026.
1.4.1 The procedures used to specify how data are collected/recorded and calculated in these test methods are regarded as the
industry standard. In addition, they are representative of the significant digits that should generally be retained. The procedures
used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s
objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these
considerations. It is beyond the scope of these test methods to consider significant digits used in analysis methods for engineering
design.
1.4.2 Measurements made to more significant digits or better sensitivity than specified in these test methods shall not be
regarded a nonconformance with this standard.
1.5 ThisstandardiswrittenusingSIunits.Inch-poundunitsareprovidedforconvenience.Thevaluesstatedininchpoundunits
maynotbeexactequivalents;therefore,theyshallbeusedindependentlyoftheSIsystem.Combiningvaluesfromthetwosystems
may result in nonconformance with this standard.
1.5.1 The gravitational system of inch-pound units is used when dealing with inch-pound units. In this system, the pound (lbf)
representsaunitofforce(weight),whiletheunitformassisslugs.Therationalizedslugunitisnotgiven,unlessdynamic(F = ma)
calculations are involved.
1.5.2 It is common practice in the engineering/construction profession to concurrently use pounds to represent both a unit of
mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and the
gravitational system. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single
standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit for
3
mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft shall not be regarded
as nonconformance with this standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It i
...
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