ASTM D5777-2018 Standard Guide for Using the Seismic Refraction Method for Subsurface Investigation.pdf

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1、Designation: D5777 18Standard 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, the year of last revi

2、sion. 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 ApplicationThis guide covers theequipment, field procedures, and interpretation methods for theassessment of subsur

3、face conditions using the seismic refrac-tion method. Seismic refraction measurements as described inthis guide are applicable in mapping subsurface conditions forvarious uses including geologic, geotechnical, hydrologic,environmental (1), mineral exploration, petroleum exploration,and archaeologica

4、l investigations. The seismic refractionmethod is used to map geologic conditions including depth ofbedrock, or the water table, stratigraphy, lithology, structure,and fractures or all of these. The calculated seismic wavevelocity is related to mechanical material properties. Therefore,characterizat

5、ion 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 SI units.1.2 Limitations:1.2.1 This guide provides an overview of the seismicrefraction method using compres

6、sional (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 considered an essentialpart of this guide. It is recommended that the user of theseismic refraction method be fa

7、miliar 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 approachto seismic refraction measurements made on land. The seismicrefraction method can be adapted for a number of

8、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 cases in which shear waves need tobe measured to satisfy project requirements. The measurementof seismic shear

9、 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 seismicrefraction method are commonly used, widely accepted, andproven; however, other approaches or modifications to

10、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,D4428/D4428M, D5088, D5730, D5753, D6235, and D6429.1.3 Precautions:1.3.1 It is the responsibility of the user of

11、 this guide tofollow any precautions within the equipment manufacturersrecommendations, establish appropriate health and safetypractices, and consider the safety and regulatory implicationswhen explosives are used.1.3.2 If the method is applied at sites with hazardousmaterials, operations, or equipm

12、ent, 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 does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility

13、of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of act

14、ion. 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 is not intended to repre-sent or replace the standard of care by which the adequacy ofa given

15、professional service must be judged, nor 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.1.6 This international standard was developed

16、 in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for the1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.01 on Surface and SubsurfaceCharacterization

17、.Current edition approved Dec. 15, 2018. Published January 2019. Originallyapproved in 1995. Last previous edition approved in 2011 as D5777 00 (2011)1.DOI: 10.1520/D5777-18.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis internat

18、ional standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Commit

19、tee.1Development of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D420 Guide for Site Characterization for Engineering De-sign and Construction PurposesD653 Terminology

20、 Relating to Soil, Rock, and ContainedFluidsD2845 Test Method for Laboratory Determination of PulseVelocities and Ultrasonic Elastic Constants of Rock(Withdrawn 2017)3D4428/D4428M Test Methods for Crosshole Seismic Test-ingD5088 Practice for Decontamination of Field EquipmentUsed at Waste SitesD5608

21、 Practices for Decontamination of Sampling and NonSample Contacting Equipment Used at Low Level Radio-active Waste SitesD5730 Guide for Site Characterization for EnvironmentalPurposes With Emphasis on Soil, Rock, the Vadose Zoneand Groundwater (Withdrawn 2013)3D5753 Guide for Planning and Conducting

22、 GeotechnicalBorehole Geophysical LoggingD6235 Practice for Expedited Site Characterization of Va-dose Zone and Groundwater Contamination at HazardousWaste Contaminated SitesD6429 Guide for Selecting Surface Geophysical Methods3. Terminology3.1 Definitions:3.1.1 For definitions of common technical t

23、erms used in thisstandard, refer to Terminology D653.4. Summary of Guide4.1 Summary of the MethodMeasurements of the traveltime of a compressional (P) wave from a seismic source to ageophone(s) are made from the land surface and are used tointerpret subsurface conditions and materials. This travel t

24、ime,along with distance between the source and geophone(s), isinterpreted to yield the depth of the refractors (refractinglayers). The calculated seismic velocities of the layers are usedto characterize some of the properties of natural or man-madesubsurface materials.4.2 Complementary DataGeologic

25、and water table dataobtained from borehole logs, geologic maps, data from out-crops or other complementary surface and borehole geophysi-cal methods may be necessary to properly interpret subsurfaceconditions from seismic refraction data.5. Significance and Use5.1 Concepts:5.1.1 This guide summarize

26、s the equipment, fieldprocedures, and interpretation methods used for the determi-nation of the depth, thickness and the seismic velocity ofsubsurface soil and rock or engineered materials, using theseismic refraction method.5.1.2 Measurement of subsurface conditions by the seismicrefraction method

27、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 source must beplaced in firm contact with the soil or rock. The geophones areusually located in a line, sometimes referred to as a geophonesp

28、read. 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 refractors orspecial conditions that require greater energy. Geophonesconvert the ground vibrations into an electrical signal. Thiselectric

29、al 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 record using twelve geophones.2For referenced ASTM

30、 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.3The last approved version of this historical standard is referenced onwww.astm.o

31、rg.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 (c= Critical Angle)D5777 1825.1.4 The seismic energy source generates elastic waves thattravel through the soil or rock from the source. When theseismic wave

32、reaches the interface between two materials ofdifferent seismic velocities, the waves are refracted accordingto Snells Law (3, 4). When the angle of incidence equals thecritical angle at the interface, the refracted wave moves alongthe interface between two materials, transmitting energy backto the

33、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 the 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 Vp

34、is dependent upon the bulkmodulus, the shear modulus and the density in the followingmanner (3):Vp5 =K14/3!/# (1)where:Vp= compressional wave velocity,K = bulk modulus, = shear modulus, and = density.5.1.7 The arrival of energy from the seismic source at eachgeophone is recorded by the seismograph (

35、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 fromeach 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 geo

36、phone to make a time distanceplot. Fig. 4 shows the source and geophone layout and theresulting idealized time distance plot for a horizontal 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

37、depth of the refractor and theseismic velocities of the materials through which the wavepasses.5.1.10 The depth of a refractor is calculated using the sourceto geophone geometry (spacing and elevation), determining theapparent seismic velocities (which are the reciprocals of theNOTE 1Arrow marks arr

38、ival of first compressional wave.FIG. 2 A Typical Seismic Waveform from a Single GeophoneFIG. 3 Twelve-Channel Analog Seismograph Record ShowingGood First Breaks Produced by an Explosive Sound Source (2)FIG. 4 (a) Seismic Raypaths and (b) Time-Distance Plot for aTwo-Layer Earth With Parallel Boundar

39、ies (2)D5777 183slopes 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 crossover distance-depthformulas have been derived in the literature (5-4). Thesederivations are straightforward inasmuch as

40、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 formulas are based on thefollowing assumptions: (1) the boundaries between layers areplanes that are either horizontal or dipp

41、ing 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) intermediate layers must be ofsufficient velocity contrast, thickness and lateral extent to bedetected. Reference (2) provide

42、s 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=V2!22 V1!2(2)where:z = depth of refractor two,ti= intercept time,V2= seismic velocity in layer two, andV1= seismic veloci

43、ty in layer one.5.1.10.2 Crossover distance formula:z 5xc2V22 V1V21V1(3)where:z, V2and V1are as defined above and xc= crossover distance.5.1.10.3 Three to four layers are usually the most that can beresolved by seismic refraction measurements. Fig. 5 shows thesource and geophone layout and the resul

44、ting time distance plotfor an idealized three-layer case.NOTE 1While these equations are suitable for hand calculations, moreadvanced algorithms are used in commercially available software that isgenerally used to analyze seismic traces.5.1.11 The refraction method is used to define the depth toor p

45、rofile of the top of one or more refractors, or both, forexample, depth of water table or bedrock.5.1.12 The source of energy 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, som

46、etimes incorrectly called reciprocalmeasurements, from which separate time distance plots aremade. Fig. 6 shows the source 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 appar

47、ent velocity of the refractor. Bothmeasurements are necessary to resolve the true seismic veloc-ity and the dip of layers (2) unless other data are available thatindicate a horizontal layered earth. These two apparent velocitymeasurements and the intercept time or crossover distance areused to calcu

48、late the true velocity, depth and dip of therefractor. Note that only two depths of the planar refractor areobtained using this approach (see Fig. 7). Depth of the refractoris obtained under each geophone by using a more sophisticateddata collection and interpretation approach.5.1.13 Most refraction

49、 surveys for geologic, engineering,hydrologic and environmental applications are carried out todetermine depths of refractors 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 (5).5.2 Parameter Measured and Representative Values:FIG. 5 (a) Seismic Raypaths and (b) Time-Distance Plot for aThree-Layer Model With Parallel Boundaries (2)FIG. 6 (a) Seismic Raypaths and (b) Time-Distance Plot for aTwo-Layer Model With A Dipping Boundary (2)D5777 1845.2.1 The seismic re