1、Designation: D7128 05 (Reapproved 2010)Standard Guide forUsing the Seismic-Reflection Method for ShallowSubsurface Investigation1This standard is issued under the fixed designation D7128; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year 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. Scope1.1 Purpose and Application:1.1.1 This guide summarizes the technique, equipment, fieldprocedures, data p
3、rocessing, and interpretation methods for theassessment of shallow subsurface conditions using the seismic-reflection method.1.1.2 Seismic reflection measurements as described in thisguide are applicable in mapping shallow subsurface conditionsfor various uses including geologic (1), geotechnical, h
4、ydro-geologic (2), and environmental (3).2The seismic-reflectionmethod is used to map, detect, and delineate geologic condi-tions including the bedrock surface, confining layers (aquita-rds), faults, lithologic stratigraphy, voids, water table, fracturesystems, and layer geometry (folds). The primar
5、y applicationof the seismic-reflection method is the mapping of lateralcontinuity of lithologic units and, in general, detection ofchange in acoustic properties in the subsurface.1.1.3 This guide will focus on the seismic-reflection methodas it is applied to the near surface. Near-surface seismicref
6、lection applications are based on the same principles asthose used for deeper seismic reflection surveying, but ac-cepted practices can differ in several respects. Near-surfaceseismic-reflection data are generally high-resolution (dominantfrequency above 80 Hz) and image depths from around6mtoas muc
7、h as several hundred meters. Investigations shallowerthan 6 m have occasionally been undertaken, but these shouldbe considered experimental.1.2 Limitations:1.2.1 This guide provides an overview of the shallowseismic-reflection method, but it does not address the details ofseismic theory, field proce
8、dures, data processing, or interpre-tation of the data. Numerous references are included for thatpurpose and are considered an essential part of this guide. It isrecommended that the user of the seismic-reflection method befamiliar with the relevant material in this guide, the referencescited in the
9、 text, and Guides D420, D653, D2845, D4428/D4428M, Practice D5088, Guides D5608, D5730, D5753,D6235, and D6429.1.2.2 This guide is limited to two-dimensional (2-D) shal-low seismic-reflection measurements made on land. Theseismic-reflection method can be adapted for a wide variety ofspecial uses: on
10、 land, within a borehole, on water, and in threedimensions (3-D). However, a discussion of these specializedadaptations of reflection measurements is not included in thisguide.1.2.3 This guide provides information to help understandthe concepts and application of the seismic-reflection methodto a wi
11、de range of geotechnical, engineering, and groundwaterproblems.1.2.4 The approaches suggested in this guide for theseismic-reflection method are commonly used, widely ac-cepted, and proven; however, other approaches or modifica-tions to the seismic-reflection method that are technicallysound may be
12、equally suited.1.2.5 Technical limitations of the seismic-reflection methodare discussed in 5.4.1.2.6 This guide discusses both compressional (P) and shear(S) wave reflection methods. Where applicable, the distinctionsbetween the two methods will be pointed out in this guide.1.3 This guide offers an
13、 organized collection of informationor 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. This gui
14、de is not intended to represent orreplace the standard of care by which the adequacy of a givenprofessional service must be judged, nor should this documentbe applied without consideration for a projects many uniqueaspects. The word “Standard” in the title of this guide meansonly that the document h
15、as been approved through the ASTMconsensus process.1.4 The values stated in SI units are regarded as standard.The values given in parentheses are inch-pound units, whichare provided for information only and are not consideredstandard.1This guide is under the jurisdiction ofASTM Committee D18 on Soil
16、 and Rockand is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization.Current edition approved May 1, 2010. Published September 2010. Originallyapproved in 2005. Last previous edition approved in 2005 as D712805. DOI:10.1520/D7128-05R10.2The boldface numbers in p
17、arentheses refer to the list of references at the end ofthis standard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.5 Precautions:1.5.1 It is the responsibility of the user of this guide tofollow any precautions within the equipm
18、ent manufacturersrecommendations, establish appropriate health and safetypractices, and consider the safety and regulatory implicationswhen explosives or any high-energy (mechanical or chemical)sources are used.1.5.2 If the method is applied at sites with hazardousmaterials, operations, or equipment
19、, it is the responsibility ofthe user of this guide to establish appropriate safety and healthpractices and determine the applicability of any regulationsprior to use.1.5.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility o
20、f the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D420 Guide to Site Characterization for Engineering De-sign and Construction PurposesD653 Terminology R
21、elating to Soil, Rock, and ContainedFluidsD2845 Test Method for Laboratory Determination of PulseVelocities and Ultrasonic Elastic Constants of RockD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD
22、4428/D4428M Test Methods for Crosshole Seismic Test-ingD5088 Practice for Decontamination of Field EquipmentUsed at Waste SitesD5608 Practices for Decontamination of Field EquipmentUsed at Low Level Radioactive Waste SitesD5730 Guide for Site Characterization for EnvironmentalPurposes With Emphasis
23、on Soil, Rock, the Vadose Zoneand Ground WaterD5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD5777 Guide for Using the Seismic Refraction Method forSubsurface InvestigationD6235 Practice for Expedited Site Characterization of Va-dose Zone and Ground Water Contamination at Hazar
24、dousWaste Contaminated SitesD6429 Guide for Selecting Surface Geophysical MethodsD6432 Guide for Using the Surface Ground PenetratingRadar Method for Subsurface Investigation3. Terminology3.1 Definitions:3.1.1 For general terms, See Terminology D653. Additionaltechnical terms used in this guide are
25、defined in Refs (4) and(5).3.2 Definitions Specific to This Guide3.2.1 acoustic impedanceproduct of seismic compres-sional wave velocity and density. Compressional wave velocityof a material is dictated by its bulk modulus, shear modulus,and density. Seismic impedance is the more general term forthe
26、 product of seismic velocity and density.3.2.2 automatic gain control (AGC)trace amplitude ad-justment that varies as a function of time and the amplitude ofadjacent data points. Amplitude adjustment changing the out-put amplitude so that at least one sample is at full scaledeflection within a selec
27、ted moving window (moving in time).3.2.3 body wavesP- and S-waves that travel through thebody of a medium, as opposed to surface waves which travelalong the surface of a half-space.3.2.4 bulk modulus (elastic constant)the resistance of amaterial to change its volume in response to the hydrostaticloa
28、d. Bulk modulus (K) is also known as the modulus ofcompression.3.2.5 check shot surveydirect measurement of traveltimebetween the surface and a given depth. Usually sources on thesurface are recorded by a seismic receiver in a well todetermine the time-to-depth relationships at a specified loca-tion
29、. Also referred to as downhole survey.3.2.6 coded sourcea seismic energy-producing devicethat delivers energy throughout a given time in a predeterminedor predicted fashion.3.2.7 common mid-point (CMP) or common depth point(CDP) methoda recording-processing method in which eachsource is recorded at
30、a number of geophone locations and eachgeophone location is used to record from a number of sourcelocations. After corrections, these data traces are combined(stacked) to provide a common-midpoint section approximat-ing a coincident source and receiver at each location. Theobjective is to attenuate
31、random effects and events whosedependence on offset is different from that of primary reflec-tions.3.2.8 compressional wave velocityalso known as P-wavevelocity. In seismic usage, velocity refers to the propagationrate of a seismic wave without implying any direction, that is,velocity is a property
32、of the medium. Particle displacement ofa compressional wave is in the direction of propagation.3.2.9 dynamic rangethe ratio of the maximum reading tothe minimum reading which can be recorded by and read froman instrument without change of scale. It is also referred to asthe ability of a system to re
33、cord very large and very smallamplitude signals and subsequently recover them. Integral tothe concept of dynamic range is the systems Analog to Digitalconverter (A/D). A systems A/D is rated according to thenumber of bits the analog signal is segmented into to form thedigital word. A/D converters in
34、 modern seismographs usuallyrange from 16 to 24 bits.3.2.10 fold (or redundancy)the multiplicity of common-midpoint data or the number of midpoints per bin. Where themidpoint is the same for 12 source/receiver pairs, the stack isreferred to as “12-fold” or 1200 percent.3.2.11 G-forcemeasure of accel
35、eration relative to thegravitational force of the earth.3For referenced ASTM standards, visit the ASTM website, 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.D7128
36、 05 (2010)23.2.12 impedance contrastratio of the seismic impedanceacross a boundary. Seismic impedance of the lower layerdivided by the seismic impedance of the upper layer.Avalue of1 implies total transmittance. Values increase or decrease from1 as the contrast increases, that is, more energy refle
37、ction froma boundary. Values less than 1 are indicative of a negativereflectivity or reversed reflection wavelet polarity.3.2.13 normal moveout (NMO)the difference inreflection-arrival time as a function of shot-to-geophone dis-tance because the geophone is not located at the source point.It is the
38、additional traveltime required because of offset,assuming that the reflecting bed is not dipping and thatraypaths are straight lines. This leads to a hyperbolic shape fora reflection.3.2.14 normal moveout velocity (stacking velocity)velocity to a given reflector calculated from normal-moveoutmeasure
39、ments, assuming a constant-velocity model. Becausethe raypath actually curves as the velocity changes, fitting ahyperbola assumes that the actual velocity distribution isequivalent to a constant NMO velocity, but the NMO velocitychanges with the offset. However, the assumption often pro-vides an ade
40、quate solution for offsets less than the reflectordepth. Used to calculate NMO corrections to common-midpoint gathers prior to stacking.3.2.15 Nyquist frequencyalso known as the aliasing orfolding frequency, is equal to half the sampling frequency orrate.Any frequency arriving at the recording instr
41、ument greaterthan the Nyquist will be aliased to a lower frequency andcannot be recovered.3.2.16 optimum windowrange of offsets between sourceand receiver that provide reflections with the best signal-to-noise ratio.3.2.17 Poissons ratiothe ratio of the transverse contrac-tion to the fractional long
42、itudinal extension when a rod isstretched. If density is known, specifying Poissons ratio isequivalent to specifying the ratio of Vs/Vp, where Vsand VpareS- and P-wave velocities. Values ordinarily range from 0.5 (noshear strength, for example, fluid) to 0, but theoretically theyrange from 0.5 to 1.
43、0; = =10.5(Vp/Vs)2/ 1(Vp/Vs)2.3.2.18 raypatha line everywhere perpendicular to wave-fronts (in isotropic media). A raypath is characterized by itsdirection at the surface. While seismic energy does not travelonly along raypaths, raypaths constitute a useful method ofdetermining arrival time by ray t
44、racing.3.2.19 reflectionthe energy or wave from a seismic sourcethat has been reflected (returned) from an acoustic-impedancecontrast (reflector) or series of contrasts within the earth.3.2.20 reflectoran interface having a contrast in physicalproperties (elasticity and/or density) that reflects sei
45、smic en-ergy.3.2.21 roll-along switcha switch that connects differentgeophone groups to the recording instruments, used incommon-midpoint recording.3.2.22 seismic impedanceproduct of seismic wave veloc-ity and density. Different from acoustic impedance as itincludes shear waves and surface waves whe
46、re acoustic im-pedance, by strict definition, includes only compressionalwaves.3.2.23 seismic sensorreceivers designed to couple to theearth and record vibrations (for example, geophones, acceler-ometers, hydrophones).3.2.24 seismic sensor group (spread)multiple receiversconnected to a single record
47、ing channel, generally deployed inan array designed to enhance or attenuate specific energy.3.2.25 seismograma seismic record or section.3.2.26 shear modulus (G) (elastic constant)the ratio ofshear stress to shear strain of a material as a result of loadingand is also known as the rigidity modulus,
48、equivalent to thesecond Lam constant m mentioned in books on continuumtheory. For small deformations, Hookes law holds and strain isproportional to stress.3.2.27 shear wave velocity (S-wave velocity)speed ofenergy traveling with particle motion perpendicular to itsdirection of propagation (see Eq 2)
49、.3.2.28 shot gathera side-by-side display of seismic tracesthat have a common source location. Also referred to as “fieldfiles.”3.2.29 source to seismic sensor offsetthe distance fromthe source-point to the seismic sensor or to the center of aseismic sensor (group) spread.3.2.30 takeouta connection point on a multiconductorcable where seismic sensors can be connected. Takeouts areusually physically polarized to reduce the likelihood of makingthe connection backwards.3.2.31 tap testgently touching a receiver while monitor-ing on real-time di
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