1、Designation: D5777 00 (Reapproved 2011)1Standard Guide forUsing the Seismic Refraction Method for SubsurfaceInvestigation1This standard is issued under the fixed designation D5777; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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.1NOTEAdded a units statement as new 1.1.1 and revised Section 3 editorially in July 2011.1. Scope1.1 Purpose and Applica
3、tionThis guide covers the equip-ment, field procedures, and interpretation methods for theassessment of subsurface conditions using the seismic refrac-tion method. Seismic refraction measurements as described inthis guide are applicable in mapping subsurface conditions forvarious uses including geol
4、ogic, geotechnical, hydrologic,environmental (1), mineral exploration, petroleum exploration,and archaeological investigations. The seismic refractionmethod is used to map geologic conditions including depth tobedrock, or to water table, stratigraphy, lithology, structure,and fractures or all of the
5、se. The calculated seismic wavevelocity is related to mechanical material properties. Therefore,characterization of the material (type of rock, degree ofweathering, and rippability) is made on the basis of seismicvelocity and other geologic information.1.1.1 The geotechnical industry uses English or
6、 SI units.1.2 Limitations:1.2.1 This guide provides an overview of the seismicrefraction method using compressional (P) waves. It does notaddress the details of the seismic refraction theory, fieldprocedures, or interpretation of the data. Numerous referencesare included for that purpose and are con
7、sidered an essentialpart of this guide. It is recommended that the user of theseismic refraction method be familiar with the relevant mate-rial in this guide and the references cited in the text and withappropriate ASTM standards cited in 2.1.1.2.2 This guide is limited to the commonly used approach
8、to seismic refraction measurements made on land. The seismicrefraction method can be adapted for a number of special uses,on land, within a borehole and on water. However, a discussionof these other adaptations of seismic refraction measurementsis not included in this guide.1.2.3 There are certain c
9、ases in which shear waves need tobe measured to satisfy project requirements. The measurementof seismic shear waves is a subset of seismic refraction. Thisguide is not intended to include this topic and focuses only onP wave measurements.1.2.4 The approaches suggested in this guide for the seismicre
10、fraction method are commonly used, widely accepted, andproven; however, other approaches or modifications to theseismic refraction method that are technically sound may besubstituted.1.2.5 Technical limitations and interferences of the seismicrefraction method are discussed in D420, D653, D2845,D442
11、8/D4428M, D5088, D5730, D5753, D6235, and D6429.1.3 Precautions:1.3.1 It is the responsibility of the user of this guide tofollow any precautions within the equipment manufacturersrecommendations, establish appropriate health and safety prac-tices, and consider the safety and regulatory implications
12、 whenexplosives are used.1.3.2 If the method is applied at sites with hazardousmaterials, operations, or equipment, it is the responsibility ofthe user of this guide to establish appropriate safety and healthpractices and determine the applicability of any regulationsprior to use.1.4 This standard d
13、oes not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 This guide offers an organized
14、 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 ASTM standard
15、 is not intended to repre-sent or replace the standard of care by which the adequacy of1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization.Current edition approved July 1, 2011. P
16、ublished September 2011. Originallyapproved in 1995. Last previous edition approved in 2006 as D577700(2006).DOI: 10.1520/D5777-00R11e1.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.a given professional service must be judged, nor
17、should thisdocument be applied without consideration of a projects manyunique aspects. The word “Standard” in the title of this guidemeans only that the document has been approved through theASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D420 Guide to Site Characterization for Eng
18、ineering De-sign and Construction PurposesD653 Terminology Relating to Soil, Rock, and ContainedFluidsD2845 Test Method for Laboratory Determination of PulseVelocities and Ultrasonic Elastic Constants of RockD4428/D4428M Test Methods for Crosshole Seismic Test-ingD5088 Practice for Decontamination o
19、f 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 on Soil, Rock, the Vadose Zoneand Ground WaterD5753 Guide for Planning and Conducting Boreh
20、ole Geo-physical LoggingD6235 Practice for Expedited Site Characterization of Va-dose Zone and Ground Water Contamination at HazardousWaste Contaminated SitesD6429 Guide for Selecting Surface Geophysical Methods3. Terminology3.1 Definitions:3.1.1 Definitions shall be in accordance with the terms and
21、symbols given in Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 The majority of the technical terms used in this guideare defined in Refs (2) and (3).34. Summary of Guide4.1 Summary of the MethodMeasurements of the traveltime of a compressional (P) wave from a seismic sour
22、ce to ageophone(s) are made from the land surface and are used tointerpret subsurface conditions and materials. This travel time,along with distance between the source and geophone(s), isinterpreted to yield the depth to refractors refractors (refractinglayers). The calculated seismic velocities of
23、the layers are usedto characterize some of the properties of natural or man-mademan subsurface materials.4.2 Complementary DataGeologic and water table dataobtained from borehole logs, geologic maps, data from out-crops or other complementary surface and borehole geophysi-cal methods may be necessar
24、y to properly interpret subsurfaceconditions from seismic refraction data.5. Significance and Use5.1 Concepts:5.1.1 This guide summarizes the equipment, field proce-dures, and interpretation methods used for the determination ofthe depth, thickness and the seismic velocity of subsurface soiland rock
25、 or engineered materials, using the seismic refractionmethod.5.1.2 Measurement of subsurface conditions by the seismicrefraction method requires a seismic energy source, triggercable (or radio link), geophones, geophone cable, and aseismograph (see Fig. 1).5.1.3 The geophone(s) and the seismic sourc
26、e must beplaced in firm contact with the soil or rock. The geophones areusually located in a line, sometimes referred to as a geophonespread. The seismic source may be a sledge hammer, amechanical device that strikes the ground, or some other typeof impulse source. Explosives are used for deeper ref
27、ractors orspecial conditions that require greater energy. Geophones2For 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 we
28、bsite.3The boldface numbers given in parentheses refer to a list of references at theend of the text.FIG. 1 Field Layout of a Twelve-Channel Seismograph Showing the Path of Direct and Refracted Seismic Waves in a Two-Layer Soil/Rock System (ac= Critical Angle)D5777 00 (2011)12convert the ground vibr
29、ations into an electrical signal. Thiselectrical signal is recorded and processed by the seismograph.The travel time of the seismic wave (from the source to thegeophone) is determined from the seismic wave form. Fig. 2shows a seismograph record using a single geophone. Fig. 3shows a seismograph reco
30、rd using twelve geophones.5.1.4 The seismic energy source generates elastic waves thattravel through the soil or rock from the source. When theseismic wave reaches the interface between two materials ofdifferent seismic velocities, the waves are refracted accordingto Snells Law (4, 8). When the angl
31、e of incidence equals thecritical angle at the interface, the refracted wave moves alongthe interface between two materials, transmitting energy backto the surface (Fig. 1). This interface is referred to as arefractor.5.1.5 A number of elastic waves are produced by a seismicenergy source. Because th
32、e compressional P-wave has thehighest seismic velocity, it is the first wave to arrive at eachgeophone (see Fig. 2 and Fig. 3).5.1.6 The P-wave velocity Vpis dependent upon the bulkmodulus, the shear modulus and the density in the followingmanner (4):Vp5 =K 1 4/3!/r (1)where:Vp= compressional wave v
33、elocity,K = bulk modulus, = shear modulus, andr = density.5.1.7 The arrival of energy from the seismic source at eachgeophone is recorded by the seismograph (Fig. 3). The traveltime (the time it takes for the seismic P-wave to travel from theseismic energy source to the geophone(s) is determined fro
34、meach waveform. The unit of time is usually milliseconds (1 ms= 0.001 s).5.1.8 The travel times are plotted against the distancebetween the source and the geophone to make a time distanceplot. Fig. 4 shows the source and geophone layout and theresulting idealized time distance plot for a horizontal
35、two-layered earth.5.1.9 The travel time of the seismic wave between theseismic energy source and a geophone(s) is a function of thedistance between them, the depth to the refractor and theseismic velocities of the materials through which the wavepasses.5.1.10 The depth to a refractor is calculated u
36、sing the sourceto geophone geometry (spacing and elevation), determining theapparent seismic velocities (which are the reciprocals of theslopes of the plotted lines in the time distance plot), and theintercept time or crossover distances on the time distance plot(see Fig. 4). Intercept time and cros
37、sover distance-depthformulas have been derived in the literature (6-8). Thesederivations are straightforward inasmuch as the travel time ofthe seismic wave is measured, the velocity in each layer iscalculated from the time-distance plot, and the raypath geom-etry is known. These interpretation formu
38、las are based on thefollowing assumptions: (1) the boundaries between layers areplanes that are either horizontal or dipping at a constant angle,(2) there is no land-surface relief, (3) each layer is homoge-neous and isotropic, (4) the seismic velocity of the layersincreases with depth, and (5) inte
39、rmediate layers must be ofsufficient velocity contrast, thickness and lateral extent to bedetected. Reference (9) provides an excellent summary of theseequations for two and three layer cases. The formulas for atwo-layered case (see Fig. 4) are given below.5.1.10.1 Intercept-time formula:z 5ti2V2V1=
40、V2!22 V1!2(2)where:z = depth to refractor two,ti= intercept time,V2= seismic velocity in layer two, andV1= seismic velocity in layer one.5.1.10.2 Crossover distance formula:z 5xc2V22 V1V21 V1(3)NOTEArrow marks arrival of first compressional wave.FIG. 2 A Typical Seismic Waveform from a Single Geopho
41、neFIG. 3 Twelve-Channel Analog Seismograph Record ShowingGood First Breaks Produced by an Explosive Sound Source (9)D5777 00 (2011)13where:z, V2and V1are as defined above and xc= crossover distance.5.1.11 Three to four layers are usually the most that can beresolved by seismic refraction measurement
42、s. Fig. 5 shows thesource and geophone layout and the resulting time distance plotfor an idealized three-layer case.5.1.12 The refraction method is used to define the depth toor profile of the top of one or more refractors, or both, forexample, depth to water table or bedrock.5.1.13 The source of en
43、ergy is usually located at or neareach end of the geophone spread; a refraction measurement ismade in each direction. These are referred to as forward andreverse measurements, sometimes incorrectly called reciprocalmeasurements, from which separate time distance plots aremade. Fig. 6 shows the sourc
44、e and geophone layout and theresulting time distance plot for a dipping refractor. The velocityobtained for the refractor from either of these two measure-ments alone is the apparent velocity of the refractor. Bothmeasurements are necessary to resolve the true seismic veloc-ity and the dip of layers
45、 (9) unless other data are available thatindicate a horizontal layered earth. These two apparent velocitymeasurements and the intercept time or crossover distance areused to calculate the true velocity, depth and dip of therefractor. Note that only two depths of the planar refractor areobtained usin
46、g this approach (see Fig. 7). Depth to the refractoris obtained under each geophone by using a more sophisticateddata collection and interpretation approach.5.1.14 Most refraction surveys for geologic, engineering,hydrologic and environmental applications are carried out todetermine depths of refrac
47、tors that are less than 100 m (about300 ft). However, with sufficient energy, refraction measure-ments can be made to depths of 300 m (1000 ft) and more (6).5.2 Parameter Measured and Representative Values:5.2.1 The seismic refraction method provides the velocity ofcompressional P-waves in subsurfac
48、e materials. Although theFIG. 4 (a) Seismic Raypaths and (b) Time-Distance Plot for aTwo-Layer Earth With Parallel Boundaries (9)FIG. 5 (a) Seismic Raypaths and (b) Time-Distance Plot for aThree-Layer Model With Parallel Boundaries (9)FIG. 6 (a) Seismic Raypaths and (b) Time-Distance Plot for aTwo-L
49、ayer Model With A Dipping Boundary (9)D5777 00 (2011)14P-wave velocity is a good indicator of the type of soil or rock,it is not a unique indicator. Table 1 shows that each type ofsediment or rock has a wide range of seismic velocities, andmany of these ranges overlap. While the seismic refractiontechnique measures the seismic velocity of seismic waves inearth materials, it is the interpreter who, based on knowledge ofthe local conditions and other data, must interpret the seismicrefraction data and arrive at a geologically feasible solution.5.2.2 P-wave vel
