1、Designation: D 6432 99 (Reapproved 2005)Standard Guide forUsing the Surface Ground Penetrating Radar Method forSubsurface Investigation1This standard is issued under the fixed designation D 6432; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 Purpose and Application:1.1.1 This guide covers the equipment, field procedures, andinterpre
3、tation methods for the 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
4、(dielectric permittivity, 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 tha
5、t propagate in the subsurface 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 veloci
6、ty in the subsurface 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
7、), depth and thickness 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 ,m
8、apping landfill and 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 railroa
9、d trackbed studies (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); P
10、lumb (17), various Proceedings 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), andDaniels (20) provide overviews of the GPR meth
11、od.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 of this guide.It is recommended that the user o
12、f the GPR method be familiarwith the relevant material within this guide and the referencescited in the text and with Guides D 420, D 5730, D 5753,D 6429, and D 6235.1.2.2 This guide is limited to the commonly used approachto GPR measurements from the ground surface. The methodcan be adapted for a n
13、umber of special uses on ice (Haeni et al(21); Wright et al (22), within or between boreholes (Lane etal (23); Lane et al (24), on water (Haeni (25), and airborne(Arcone et al (25) applications. A discussion of these otheradaptations of GPR measurements is not included in this guide.1.2.3 The approa
14、ches 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 offers an organized collection of informa-tio
15、n 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 professionaljudgements. Not all aspects of this guide may be applicable inall circumstances. This ASTM standard is not intended torep
16、resent or replace the standard of care by which theadequacy of a given professional service must be judged, norshould this document be applied without consideration of a1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.01
17、on Surface and SubsurfaceCharacterization.Current edition approved May 1, 2005. Published December 2005. Originallyapproved in 1999. Last previous edition approved in 1999 as D 6432 99.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.1Copyright ASTM Int
18、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.projects many unique aspects. The word “Standard” in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.1.3 Precautions:1.3.1 It is the responsibili
19、ty 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 guide method is used at sites with hazardousmaterials, operations, or equipment, it is the responsibility ofthe user of this gui
20、de 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 of the safetyconcerns that may be associated with the use of the GPRmethod. It is the responsibility of the user of this guide toe
21、stablish appropriate safety and health practices and todetermine the applicability of regulations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 420 Guide to Site Characterization for Engineering, De-sign, and Construction PurposesD 653 Terminology Relating to Soil, Rock, and ContainedFlu
22、idsD 5730 Guide for Site Characterization for EnvironmentalPurposes With Emphasis on Soil, Rock, the Vadose Zoneand Ground WaterD 5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD 6235 Guide for Expedited Site Characterization of Haz-ardous Waste Contaminated SitesD 6429 Guide fo
23、r Selecting Surface Geophysical Methods3. Terminology3.1 Definitions:3.1.1 Definitions shall be in accordance with the terms andsymbols given in Terminology D 653.3.1.2 The majority of the technical terms used in this guideare defined in Sheriff (27).3.1.3 Additional Definitions:3.1.3.1 antennaa tra
24、nsmitting 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.3.1.3.2 attenuation(1) the loss of EM wave energy due toconduction currents associated wit
25、h finite conductivity (s) andthe dielectric relaxation (also referred to as polarization loss)associated with the imaginary component of the permittivity(e9), and magnetic relaxation associated with the imaginarycomponent of magnetic permeability.(2) The term “attenuation” is also sometimes used to
26、refer tothe loss in EM wave energy from all possible sources,including conduction currents, dielectric relaxation, scattering,and geometrical spreading.3.1.3.3 bandwidthThe operating frequency range of anantenna that conforms to a specified standard (Balanis (28).For GPR antennas, typically the band
27、width 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 frequencies is used todescribe an antennas bandwidth. For
28、 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 to the centerfrequency is commonly used. In the prece
29、ding case, one wouldhave a ratio of 400:400 or 1:1.3.1.3.4 bistaticthe survey method that utilizes antennas.One antenna radiates the EM waves and the other antennareceives the reflected waves.3.1.3.5 conductivitythe ability of a material to support anelectrical current (material property that descri
30、bes the move-ment of electrons or ions) due to an applied electrical field. Theunits of conductivity are Siemens/metre (S/m).3.1.3.6 control unit (C/U)An electronic instrument thatcontrols GPR data collection. The control unit may alsoprocess, display, and store the GPR data.3.1.3.7 couplingthe coup
31、ling 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 impedance equal to the impedance ofthe ground.3.1.3.8 depth of penetratio
32、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 levels of the GPR unit.(1) In a conductive material (seawater, metallic m
33、aterials, 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 tens to thousands of metres.3.1.3.9 dielectric permittivitydielectric per
34、mittivity 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 response to the application of an electricfield, E, through D=e E. The units
35、of dielectric permittivity, e,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 the dielectric permittivity is greater than that of freespace, it must b
36、e complex and lossy, with frequency depen-dence typically described by the Cole-Cole (Cole and Cole(28) relaxation distribution model. Nearly all dielectric relax-ation processes are the result of the presence of water or clayminerals (Olhoeft (29).3For referenced ASTM standards, visit the ASTM webs
37、ite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.D 6432 99 (2005)23.1.3.10 dielectric relaxationgenerally used to describeEM wave attenuation due to e9 (the imag
38、inary 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 relaxation time.3.1.3.11 diffusionthe process by which the applicatio
39、n 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 magnetic field.Diffusion is the low-frequency, high-loss, limiting
40、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.3.1.3.12 dipole antennaa linear polarization antenna con-sisting of two wires fed at the middle by a
41、 balanced source(Balanis (27).3.1.3.13 Fresnel zonethe 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 from the target. There aremultiple Fresnel zones that form annu
42、lar rings around the firstFresnel zone (Sheriff (26).3.1.3.14 loss tangentThere 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 thestorage parts of the response to the stimulus in the force-fluxstimul
43、us-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 representsthe cotangent of the phase between E and J (electric andcur
44、rent 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 electro-magnetic loss tangent is the ratio of the real to the imagi
45、naryparts of the complex propagation constant, and it represents thecotangent of the phase angle between E and H.3.1.3.15 magnetic permeability ()the property that de-scribes the ability of a material to store magnetic energy byrealignment of electron spin and motion. It relates ability of amaterial
46、 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 ratio of the permeability of a material to that of freespace, 4p3107H/
47、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-Cole (Cole and Cole (28) relaxationmodel. Nearly all magnetic prope
48、rties are the result of thepresence of iron in a variety of mineralogical forms (Olhoeft(29). In some of the literature, magnetic susceptibility is usedwith a variety of units and normalizations (Hunt et al (30).3.1.3.16 megahertz (MHz)a unit of frequency. One mega-hertz equals 106Hz.3.1.3.17 monost
49、atic(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 are separated by a small distance relative to thedepth of interest are sometimes referred to as operating in“monostatic mode.”3.1.3.18 nanosecond (Ns) a unit of time. One nanosecondequals 109s; one billionth of a second.3.1.3.19 polarization(1) the storage of electrical or mag-netic energy by the application of electric or magnetic fields tomatter. (2) The orientati
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