ASTM D6430-18
(Guide)Standard Guide for Using the Gravity Method for Subsurface Site Characterization
Standard Guide for Using the Gravity Method for Subsurface Site Characterization
SIGNIFICANCE AND USE
5.1 Concepts—This guide summarizes the equipment, field procedures, and interpretation methods used for the determination of subsurface conditions due to density variations using the gravity method. Gravity measurements can be used to map major geologic features over hundreds of square miles and to detect shallow smaller features in soil or rock. In some areas, the gravity method can detect subsurface cavities.
5.1.1 Another benefit of the gravity method is that measurements can be made in many culturally developed areas, where other geophysical methods may not work. For example, gravity measurements can be made inside buildings; in urban areas; and in areas of cultural, electrical, and electromagnetic noise.
5.1.2 Measurement of subsurface conditions by the gravity method requires a gravimeter (Fig. 1) and a means of determining location and very accurate relative elevations of gravity stations.
5.1.2.1 The unit of measurement used in the gravity method is the Gal (in honor of Galileo), based on the gravitational force at the Earth's surface. The average gravity at the Earth's surface is approximately 980 Gal. The unit commonly used in regional gravity surveys is the mGal (10−3 Gal). Typical gravity surveys for environmental and engineering applications require measurements with an accuracy of a few μGals (10−6 Gals), they are often referred to as microgravity surveys.
5.1.2.2 A detailed gravity survey typically uses closely spaced measurement stations (a few meters to approximately 100 meters) and is carried out with a gravimeter capable of reading to a few μGals. Detailed surveys are used to assess local geologic or structural conditions.
5.1.2.3 A gravity survey consists of making gravity measurements at stations along a profile line or grid. Measurements are taken periodically at a base station (a stable noise-free reference location) to correct for instrument drift.
5.1.3 Gravity data contain anomalies that are made up of deep regional and shall...
SCOPE
1.1 Purpose and Application:
1.1.1 This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of subsurface conditions using the gravity method. However, this standard does not address the use of marine, airborne, or satellite gravity measurements.
1.1.2 The gravity method described in this guide is applicable to site characterization of a wide range of subsurface conditions.
1.1.3 Gravity measurements indicate variations in the earth's gravitational field caused by lateral differences in the density of the subsurface soil or rock or the presence of natural voids or man-made structures. By measuring spatial changes in the gravitational field, variations in subsurface conditions can be determined.
1.1.4 Detailed gravity surveys (commonly called microgravity surveys) are used for near-surface geologic site characterizations and geotechnical, environmental, and archaeological studies. Geologic and geotechnical applications include location of buried channels, bedrock structural features, voids, and caves, and low-density zones in foundations. Environmental applications include site characterization, groundwater studies, landfill characterization, and location of underground storage tanks (1)2.
1.2 Limitations:
1.2.1 This guide provides an overview of the gravity method. It does not address the details of the gravity theory, field procedures, or interpretation of the data. Numerous references are included for that purpose and are considered an essential part of this guide. It is recommended that the user of the gravity method be familiar with the references cited and with the Guides D420, D5753, D6235, and D6429, and Practices D5088, and D5608.
1.2.2 This guide is limited to gravity measurements made on land. The gravity method can be adapted for a number of special uses: on land, in a borehole, on water, and from aircraft and space. A discussion of these other...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6430 − 18
Standard Guide for
Using the Gravity Method for Subsurface Site
1
Characterization
This standard is issued under the fixed designation D6430; 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* 1.2.2 This guide is limited to gravity measurements made
on land. The gravity method can be adapted for a number of
1.1 Purpose and Application:
specialuses:onland,inaborehole,onwater,andfromaircraft
1.1.1 This guide summarizes the equipment, field
and space. A discussion of these other gravity methods,
procedures, and interpretation methods for the assessment of
including vertical gravity gradient measurements, is not in-
subsurface conditions using the gravity method. However, this
cluded in this guide.
standard does not address the use of marine, airborne, or
1.2.3 The approaches suggested in this guide for the gravity
satellite gravity measurements.
method are the most commonly used, widely accepted, and
1.1.2 The gravity method described in this guide is appli-
proven. However, other approaches or modifications to the
cable to site characterization of a wide range of subsurface
gravity method that are technically sound may be substituted.
conditions.
1.2.4 This guide offers an organized collection of informa-
1.1.3 Gravity measurements indicate variations in the
tion or a series of options and does not recommend a specific
earth’s gravitational field caused by lateral differences in the
course of action. This document cannot replace education,
densityofthesubsurfacesoilorrockorthepresenceofnatural
experience, and should be used in conjunction with profes-
voidsorman-madestructures.Bymeasuringspatialchangesin
sional judgment. Not all aspects of this guide may be appli-
the gravitational field, variations in subsurface conditions can
cable in all circumstances. This ASTM document is not
be determined.
intended to represent or replace the standard of care by which
1.1.4 Detailed gravity surveys (commonly called micro-
the adequacy of a given professional service must be judged,
gravity surveys) are used for near-surface geologic site char-
nor should this document be applied without consideration of
acterizations and geotechnical, environmental, and archaeo-
a project’s many unique aspects. The word “Standard” in the
logicalstudies.Geologicandgeotechnicalapplicationsinclude
title of this document means only that the document has been
location of buried channels, bedrock structural features, voids,
approved through the ASTM consensus process.
and caves, and low-density zones in foundations. Environmen-
tal applications include site characterization, groundwater
1.3 Units—The values stated in SI units are regarded as
studies, landfill characterization, and location of underground
standard. No other units of measurement are included in this
2
storage tanks (1) .
standard. Reporting of test results in units other than SI shall
1.2 Limitations:
not be regarded as nonconformance with this test method.
1.2.1 This guide provides an overview of the gravity
1.4 Precautions:
method. It does not address the details of the gravity theory,
1.4.1 It is the responsibility of the user of this guide to
field procedures, or interpretation of the data. Numerous
follow any precautions in the equipment manufacturer’s rec-
references are included for that purpose and are considered an
ommendations and to establish appropriate health and safety
essential part of this guide. It is recommended that the user of
practices.
the gravity method be familiar with the references cited and
1.4.2 If this guide is used at sites with hazardous materials,
with the Guides D420, D5753, D6235, and D6429, and
operations, or equipment, it is the responsibility of the user of
Practices D5088, and D5608.
this guide to establish appropriate safety and health practices
and to determine the applicability of any regulations prior to
1
ThisguideisunderthejurisdictionofASTMCommitteeD18onSoilandRock
use.
and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
1.5 This standard does not purport to address all of the
Characterization.
Current edition approved Feb. 1, 2018. Published March 2018. Originally
safety concerns, if any, associated with its use. It is the
approved in 1999. Last previous edition approved in 2010 as D6430–99(2010).
responsibility of the user of this standard to establish appro-
DOI: 10.1520/D6430-18.
2
priate safety, health, and environm
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: D6430 − 99 (Reapproved 2010) D6430 − 18
Standard Guide for
Using the Gravity Method for Subsurface InvestigationSite
1
Characterization
This standard is issued under the fixed designation D6430; 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 Scope*
1.1 Purpose and Application:
1.1.1 This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of subsurface
conditions using the gravity method. However, this standard does not address the use of marine, airborne, or satellite gravity
measurements.
1.1.2 The gravity method described in this guide is applicable to investigation site characterization of a wide range of subsurface
conditions.
1.1.3 Gravity measurements indicate variations in the earth’s gravitational field caused by lateral differences in the density of
the subsurface soil or rock or the presence of natural voids or man-made structures. By measuring spatial changes in the
gravitational field, variations in subsurface conditions can be determined.
1.1.4 Detailed gravity surveys (commonly called microgravity surveys) are used for near-surface geologic investigations site
characterizations and geotechnical, environmental, and archaeological studies. Geologic and geotechnical applications include
location of buried channels, bedrock structural features, voids, and caves, and low-density zones in foundations. Environmental
applications include site characterization, groundwater studies, landfill characterization, and location of underground storage tanks
2
(1) .
1.2 Limitations:
1.2.1 This guide provides an overview of the gravity method. It does not address the details of the gravity theory, field
procedures, or interpretation of the data. Numerous references are included for that purpose and are considered an essential part
of this guide. It is recommended that the user of the gravity method be familiar with the references cited and with the Guides D420,
D5753, D6235, and D6429, and Practices D5088, and D5608.
1.2.2 This guide is limited to gravity measurements made on land. The gravity method can be adapted for a number of special
uses: on land, in a borehole, on water, and from aircraft and space. A discussion of these other gravity methods, including vertical
gravity gradient measurements, is not included in this guide.
1.2.3 The approaches suggested in this guide for the gravity method are the most commonly used, widely accepted, and proven.
However, other approaches or modifications to the gravity method that are technically sound may be substituted.
1.2.4 This guide offers an organized collection of information or a series of options and does not recommend a specific course
of action. This document cannot replace education, experience, and should be used in conjunction with professional judgment. Not
all aspects of this guide may be applicable in all circumstances. This ASTM document is not intended to represent or replace the
standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied
without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the
document has been approved through the ASTM consensus process.
1.3 Units—The values stated in SI units are regarded as standard. No other units of measurement are included in this standard.
Reporting of test results in units other than SI shall not be regarded as nonconformance with this test method.
1.4 Precautions:
1.4.1 It is the responsibility of the user of this guide to follow any precautions in the equipment manufacturer’s
recommendations and to establish appropriate health and safety practices.
1
This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
Characterization.
Current edition approved May 1, 2010Feb. 1, 2018. Published September 2010March 2018. Originally approved in 1999. Last previous edition approved in 20052010 as
D6430–99(2005).D6430–99(2010). DOI: 10.1520/D6430-99R10.10.1520/D6430-18.
2
The boldface numbers in parentheses refer to the list of references at the end of this standard.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM In
...
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