ASTM D6431-99(2010)
(Guide)Standard Guide for Using the Direct Current Resistivity Method for Subsurface Investigation
Standard Guide for Using the Direct Current Resistivity Method for Subsurface Investigation
SIGNIFICANCE AND USE
Concepts—The resistivity technique is used to measure the resistivity of subsurface materials. Although the resistivity of materials can be a good indicator of the type of subsurface material present, it is not a unique indicator. While the resistivity method is used to measure the resistivity of earth materials, it is the interpreter who, based on knowledge of local geologic conditions and other data, must interpret resistivity data and arrive at a reasonable geologic and hydrologic interpretation.
Parameter Being Measured and Representative Values:
Table 1 shows some general trends for resistivity values. Fig. 2 shows ranges in resistivity values for subsurface materials.
Materials with either a low effective porosity or that lack conductive pore fluids have a relatively high resistivity (>1000 Ωm). These materials include massive limestones, most unfractured igneous rocks, unsaturated unconsolidated materials, and ice.
Materials that have high porosity with conductive pore fluids or that consist of or contain clays usually have low resistivity. These include clay soil and weathered rock.
Materials whose pore water has low salinity have moderately high resistivity.
The dependence of resistivity on water saturation is not linear. Resistivity increases relatively little as saturation decreases from 100 % to 40-60 % and then increases much more as saturation continues to decrease. An empirical relationship known as Archie's Law describes the relationship between pore fluid resistivity, porosity, and bulk resistivity (McNeill (8)).
Equipment—Geophysical apparatus used for surface resistivity measurement includes a source of power, a means to measure the current, a high impedance voltmeter, electrodes to make contact with the ground, and the necessary cables to connect the electrodes to the power sources and the volt meter (Fig. 1).
While resistivity measurements can be made using common electronic instruments, it is recommended that commercial resisti...
SCOPE
1.1 Purpose and Application:
1.1.1 This guide summarizes the equipment, field procedures, and interpretation methods for the assessment of the electrical properties of subsurface materials and their pore fluids, using the direct current (DC) resistivity method. Measurements of the electrical properties of subsurface materials are made from the land surface and yield an apparent resistivity. These data can then be interpreted to yield an estimate of the depth, thickness, and resistivity of subsurface layer(s).
1.1.2 Resistivity measurements as described in this guide are applied in geological, geotechnical, environmental, and hydrologic investigations. The resistivity method is used to map geologic features such as lithology, structure, fractures, and stratigraphy; hydrologic features such as depth to water table, depth to aquitard, and groundwater salinity; and to delineate groundwater contaminants. General references are, Keller and Frischknecht (1), Zohdy et al (2), Koefoed (3), EPA (4), Ward (5), Griffiths and King (6), and Telford et al (7).
1.2 Limitations:
1.2.1 This guide provides an overview of the Direct Current Resistivity Method. It does not address in detail the 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 resistivity method be familiar with the references cited in the text and with the Guide D420, Practice D5088, Practice D5608, Guide D5730, Test Method G57, D6429, and D6235.
1.2.2 This guide is limited to the commonly used approach for resistivity measurements using sounding and profiling techniques with the Schlumberger, Wenner, or dipole-dipole arrays and modifications to those arrays. It does not cover the use of a wide range of specialized arrays. It also does not include the use of spontaneous potential (SP) measurements, induced polarizati...
General Information
Relations
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: D6431 − 99 (Reapproved 2010)
Standard Guide for
Using the Direct Current Resistivity Method for Subsurface
1
Investigation
This standard is issued under the fixed designation D6431; 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 the resistivity method be familiar with the references cited in
the text and with the Guide D420, Practice D5088, Practice
1.1 Purpose and Application:
D5608, Guide D5730, Test Method G57, D6429, and D6235.
1.1.1 This guide summarizes the equipment, field
procedures, and interpretation methods for the assessment of 1.2.2 This guide is limited to the commonly used approach
for resistivity measurements using sounding and profiling
the electrical properties of subsurface materials and their pore
fluids, using the direct current (DC) resistivity method. Mea- techniques with the Schlumberger, Wenner, or dipole-dipole
surements of the electrical properties of subsurface materials arrays and modifications to those arrays. It does not cover the
are made from the land surface and yield an apparent resistiv-
use of a wide range of specialized arrays. It also does not
ity. These data can then be interpreted to yield an estimate of include the use of spontaneous potential (SP) measurements,
the depth, thickness, and resistivity of subsurface layer(s).
induced polarization (IP) measurements, or complex resistivity
1.1.2 Resistivity measurements as described in this guide
methods.
are applied in geological, geotechnical, environmental, and
1.2.3 The resistivity method has been adapted for a number
hydrologic investigations. The resistivity method is used to
of special uses, on land, within a borehole, or on water.
map geologic features such as lithology, structure, fractures,
Discussions of these adaptations of resistivity measurements
and stratigraphy; hydrologic features such as depth to water
are not included in this guide.
table, depth to aquitard, and groundwater salinity; and to
1.2.4 The approaches suggested in this guide for the resis-
delineate groundwater contaminants. General references are,
2 tivity method are the most commonly used, widely accepted
Keller and Frischknecht (1), Zohdy et al (2), Koefoed (3),
and proven; however, other approaches or modifications to the
EPA(4), Ward (5), Griffiths and King (6), and Telford et al (7).
resistivitymethodthataretechnicallysoundmaybesubstituted
1.2 Limitations:
if technically justified and documented.
1.2.1 This guide provides an overview of the Direct Current
1.2.5 This guide offers an organized collection of informa-
Resistivity Method. It does not address in detail the theory,
tion or a series of options and does not recommend a specific
field procedures, or interpretation of the data. Numerous
course of action. This document cannot replace education or
references are included for that purpose and are considered an
experienceandshouldbeusedinconjunctionwithprofessional
essential part of this guide. It is recommended that the user of
judgements. Not all aspects of this guide may be applicable in
all circumstances. This ASTM standard is not intended to
1
This guide is under the jurisdiction ofASTM CommitteeD18 on Soil and Rock
represent or replace the standard of care by which the
and is the direct responsibility of Subcommittee D18.01 on Surface and Subsurface
adequacy of a given professional service must be judged, nor
Characterization.
Current edition approved May 1, 2010. Published September 2010. Originally
should this document be applied without consideration of a
approved in 1999. Last previous edition approved in 2005 as D6431–99(2005).
project’s many unique aspects. The word “Standard” in the
DOI: 10.1520/D6431-99R10.
2 title of this document means only that the document has been
The boldface numbers in parentheses refer to the list of references at the end of
this standard. approved through the ASTM consensus process.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6431 − 99 (2010)
1.3 Precautions: 3.1.3.4 resistivity—the property of a material that resists the
1.3.1 It is the responsibility of the user of this guide to flow of electrical current. The units of resistivity are ohmme-
follow any precautions in the equipment manufacturer’s rec- tres or ohm-feet (1 Ωm = 3.28 Ω-ft).
ommendations and to consider the safety implications when
4. Summary of Guide
high voltages and currents are used.
1.3.2 If this guide is used at sites with hazardous materials,
4.1 Summary—The measurement o
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.