1、Designation: D6432 11Standard Guide forUsing the Surface Ground Penetrating Radar Method forSubsurface Investigation1This standard is issued under the fixed designation D6432; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 Purpose and Application:1.1.1 This guide covers the equipment, field procedures, andinterpretation methods for t
3、he assessment of subsurface mate-rials using the impulse Ground Penetrating Radar (GPR)Method. GPR is most often employed as a technique that useshigh-frequency electromagnetic (EM) waves (from 10 to 3000MHz) to acquire subsurface information. GPR detects changesin EM properties (dielectric permitti
4、vity, conductivity, andmagnetic permeability), that in a geologic setting, are afunction of soil and rock material, water content, and bulkdensity. Data are normally acquired using antennas placed onthe ground surface or in boreholes. The transmitting antennaradiates EM waves that propagate in the s
5、ubsurface and reflectfrom boundaries at which there are EM property contrasts. Thereceiving GPR antenna records the reflected waves over aselectable time range.The depths to the reflecting interfaces arecalculated from the arrival times in the GPR data if the EMpropagation velocity in the subsurface
6、 can be estimated ormeasured.1.1.2 GPR measurements as described in this guide are usedin geologic, engineering, hydrologic, and environmental appli-cations. The GPR method is used to map geologic conditionsthat include depth to bedrock, depth to the water table (Wrightet al (1)2), depth and thickne
7、ss of soil strata on land and underfresh water bodies (Beres and Haeni (2), and the location ofsubsurface cavities and fractures in bedrock (Ulriksen (3) andImse and Levine (4). Other applications include the locationof objects such as pipes, drums, tanks, cables, and boulders ,mapping landfill and
8、trench boundaries (Benson et al (6),mapping contaminants (Cosgrave et al (7); Brewster andAnnan (8); Daniels et al (9), conducting archaeological(Vaughan (10) and forensic investigations (Davenport et al(11), inspection of brick, masonry, and concrete structures,roads and railroad trackbed studies (
9、Ulriksen (3), and highwaybridge scour studies (Placzek and Haeni (12). Additionalapplications and case studies can be found in the variousProceedings of the International Conferences on GroundPenetrating Radar (Lucius et al (13); Hannien andAutio, (14),Redman, (15); Sato, (16); Plumb (17), various P
10、roceedings ofthe Symposium on the Application of Geophysics to Engineer-ing and Environmental Problems (Environmental and Engi-neering Geophysical Society, 19881998), and The GroundPenetrating Radar Workshop (Pilon (18), EPA (19), Daniels(20), and Jol (21) provide overviews of the GPR method.1.1.3 T
11、he geotechnical industry uses English or SI units.1.2 Limitations:1.2.1 This guide provides an overview of the impulse GPRmethod. It does not address details of the theory, field proce-dures, or interpretation of the data. References are included forthat purpose and are considered an essential part
12、of this guide.It is recommended that the user of the GPR method be familiarwith the relevant material within this guide and the referencescited in the text and with Guides D420, D5730, D5753, D6429,and D6235.1.2.2 This guide is limited to the commonly used approachto GPR measurements from the ground
13、 surface. The methodcan be adapted for a number of special uses on ice (Haeni et al(22); Wright et al (23), within or between boreholes (Lane etal (24); Lane et al (25), on water (Haeni (26), and airborne(Arcone et al (26) applications. A discussion of these otheradaptations of GPR measurements is n
14、ot included in this guide.1.2.3 The approaches suggested in this guide for using GPRare the most commonly used, widely accepted, and proven;however, other approaches or modifications to using GPR thatare technically sound may be substituted if technically justifiedand documented.1.2.4 This guide off
15、ers an organized collection of informa-tion or a series of options and does not recommend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances.
16、This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged, nor should thisdocument be applied without consideration of a projects many1This guide is under the jurisdiction ofASTM CommitteeD18 on Soil and Rocka
17、nd is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization.Current edition approved May 1, 2011. Published June 2011. Originallyapproved in 1999. Last previous edition approved in 2005 as D643299(2005).DOI: 10.1520/D6432-11.2The boldface numbers in parentheses r
18、efer to the list of references at the end ofthis standard.1*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.unique aspects. The word “Standard” in the title of thisdocum
19、ent means only that the document has been approvedthrough the ASTM consensus process.1.3 Precautions:1.3.1 It is the responsibility of the user of this guide tofollow any precautions in the equipment manufacturers rec-ommendations and to establish appropriate health and safetypractices.1.3.2 If this
20、 guide method is used at sites with hazardousmaterials, operations, or equipment, it is the responsibility ofthe user of this guide to establish appropriate safety and healthpractices and to determine the applicability of any regulationsprior to use.1.3.3 This guide does not purport to address all o
21、f the safetyconcerns that may be associated with the use of the GPRmethod. It is the responsibility of the user of this guide toestablish appropriate safety and health practices and todetermine the applicability of regulations prior to use.2. Referenced Documents2.1 ASTM Standards:3D420 Guide to Sit
22、e Characterization for Engineering De-sign and Construction PurposesD653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD5730 Guide for Site
23、Characterization for EnvironmentalPurposes With Emphasis on Soil, Rock, the Vadose Zoneand Ground WaterD5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD6235 Practice for Expedited Site Characterization of Va-dose Zone and Ground Water Contamination at HazardousWaste Contaminated
24、 SitesD6429 Guide for Selecting Surface Geophysical Methods3. Terminology3.1 Definitions:3.1.1 Definitions shall be in accordance with the terms andsymbols given in Terminology D653.3.1.2 The majority of the technical terms used in this guideare defined in Sheriff (27).3.2 Definitions of Terms Speci
25、fic to This Standard:3.2.1 antenna, n a transmitting GPR antenna converts anexcitation in the form of a voltage pulse or wave train into EMwaves. A receiving GPR antenna converts energy contained inEM waves into voltages, which are regarded as GPR data.3.2.2 attenuation, nwave, (1) the loss of EM wa
26、ve energydue to conduction currents associated with finite conductivity(s) and the dielectric relaxation (also referred to as polarizationloss) associated with the imaginary component of the permit-tivity (9), and magnetic relaxation associated with the imagi-nary component of magnetic permeability.
27、(2) The term “attenuation” is also sometimes used to refer tothe loss in EM wave energy from all possible sources,including conduction currents, dielectric relaxation, scattering,and geometrical spreading.3.2.3 bandwidth, nThe operating frequency range of anantenna that conforms to a specified stand
28、ard (Balanis (28).For GPR antennas, typically the bandwidth is defined by theupper and lower frequencies radiated from a transmitting GPRantenna that possess power that is 3 dB below the peak powerradiated from the antenna at its resonant frequency. Sometimesthe ratio of the upper and lower 3-dB fre
29、quencies is used todescribe an antennas bandwidth. For example, if the upper andlower 3-dB frequencies of an antenna are 600 and 200 MHz,respectively, the bandwidth of the antenna is said to be 3:1. InGPR system design, the ratio of the difference between theupper frequency minus the lower frequency
30、 to the centerfrequency is commonly used. In the preceding case, one wouldhave a ratio of 400:400 or 1:1.3.2.4 bistatic, adjthe survey method that uses two anten-nas. One antenna radiates the EM waves and the other antennareceives the reflected waves.3.2.5 conductivity, nelectrical, the ability of a
31、 material tosupport an electrical current (material property that describesthe movement of electrons or ions) due to an applied electricalfield. The units of conductivity are Siemens/metre (S/m).3.2.6 control unit (C/U), nAn electronic instrument thatcontrols GPR data collection. The control unit ma
32、y alsoprocess, display, and store the GPR data.3.2.7 coupling, nthe coupling of a ground penetratingradar antenna to the ground describes the ability of the antennato get electromagnetic energy into the ground. A poorlycoupled antenna is described as being mismatched. A well-coupled antenna has an i
33、mpedance equal to the impedance ofthe ground.3.2.8 depth of penetration, nthe maximum depth range aradar signal can penetrate in a given medium, be scattered byan electrical inhomogeneity, propagate back to the surface, berecorded by a receiver GPR antenna, and yield a voltagegreater than the noise
34、levels of the GPR unit.(1) In a conductive material (seawater, metallic materials, ormineralogic clay soils), attenuation can be great, and the wavemay penetrate only a short distance (less than 1 m). In aresistive material (fresh water, granite, ice, or quartz sand), thedepth of penetration can be
35、tens to thousands of metres.3.2.9 dielectric permittivity, ndielectric permittivity is theproperty that describes the ability of a material to store electricenergy by separating opposite polarity charges in space. Itrelates ability of a material to be polarized in the electricdisplacement, D, in res
36、ponse to the application of an electricfield, E, through D= E. The units of dielectric permittivity, ,are farads/metre (F/m). Relative dielectric permittivity (previ-ously called the dielectric constant) is the ratio of the permit-tivity of a material to that of free space, 8.854 3 1012F/m.Whenever
37、the dielectric permittivity is greater than that of freespace, it must be complex and lossy, with frequency depen-dence typically described by the Cole-Cole (Cole and Cole3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
38、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.D6432 112(29) relaxation distribution model. Nearly all dielectric relax-ation processes are the result of the presence of water or clayminerals (Olhoeft (30).3.2.10 dielectric relaxation, n
39、generally used to describeEM wave attenuation due to 9 (the imaginary part of thecomplex permittivity). The term is derived from the empiricalrelationship developed by describing the frequency-dependentbehavior of dielectrics. The classical Debye formulation con-tains a term referred to as the relax
40、ation time.3.2.11 diffusion, nthe process by which the application ofan external force (stimulus) results in a flux or movement ofsomething (response). In electromagnetics, diffusion describesthe movement of charges in response to an applied electric fieldor in response to an applied time-varying ma
41、gnetic field.Diffusion is the low-frequency, high-loss, limiting behavior ofelectromagnetic wave propagation and is descriptive of behav-ior that decays rapidly (exponentially) with distance and time,generally to 1/e of the initial amplitude in12 p of a wavelength.3.2.12 dipole antennaa linear polar
42、ization antenna con-sisting of two wires fed at the middle by a balanced source(Balanis (28).3.2.13 Fresnel zone, nthe area of a targets surface thatcontains the portion of the incident wave that arrives at thereceive antenna less than12 of a cycle out-of-phase fromearliest arriving reflected energy
43、 from the target. There aremultiple Fresnel zones that form annular rings around the firstFresnel zone (Sheriff (27).3.2.14 loss tangent, nThere are three loss tangents: elec-tric, magnetic, and electromagnetic. Each loss tangent is theratio of the imaginary to the real parts or the lossy to thestor
44、age parts of the response to the stimulus in the force-fluxstimulus-response equations. The electrical loss tangent is theratio of the imaginary to the real part of the dielectricpermittivity plus the electrical conductivity divided by radianfrequency times the real part of the permittivity. It repr
45、esentsthe cotangent of the phase between E and J (electric andcurrent density). The magnetic loss tangent is the ratio of theimaginary to the real part of the complex magnetic permeabil-ity. It represents the cotangent of the phase angle between Hand B (magnetic field and magnetic induction). The el
46、ectro-magnetic loss tangent is the ratio of the real to the imaginaryparts of the complex propagation constant, and it represents thecotangent of the phase angle between E and H.3.2.15 magnetic permeability (), nthe property that de-scribes the ability of a material to store magnetic energy byrealig
47、nment of electron spin and motion. It relates ability of amaterial to be magnetized (magnetic polarization) in themagnetic induction, B, in response to the application of amagnetic field H, through B=H. The units of magneticpermeability, , are Henry/metre. Relative magnetic permeabil-ity is the rati
48、o of the permeability of a material to that of freespace, 4p3107H/m. It is commonly assumed that magneticproperties are those of free space. Whenever the magneticpermeability is greater than that of free space, it must becomplex and lossy, with frequency dependence typically de-scribed by the Cole-C
49、ole (Cole and Cole (29) relaxationmodel. Nearly all magnetic properties are the result of thepresence of iron in a variety of mineralogical forms (Olhoeft(30). In some of the literature, magnetic susceptibility is usedwith a variety of units and normalizations (Hunt et al (31).3.2.16 megahertz (MHz), na unit of frequency. Onemegahertz equals 106Hz.3.2.17 monostatic, adj(1) a survey method that utilizes asingle antenna acting as both the transmitter and receiver ofEM waves. (2) Two antennas, one transmitting and onereceiving, that
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