ASTM D5882-2007(2013) 8326 Standard Test Method for Low Strain Impact Integrity Testing of Deep Foundations《深地基低应变碰撞完整性测试的标准试验方法》.pdf

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1、Designation: D5882 07 (Reapproved 2013)Standard Test Method forLow Strain Impact Integrity Testing of Deep Foundations1This standard is issued under the fixed designation D5882; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y

2、ear 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 This test method covers the procedure for determiningthe integrity of individual vertical or inclined piles by

3、measur-ing and analyzing the velocity (required) and force (optional)response of the pile induced by an (hand held hammer or othersimilar type) impact device usually applied axially and perpen-dicularly to the pile head surface.This test method is applicableto long structural elements that function

4、in a manner similar toany deep foundation units (such as driven piles, augeured piles,or drilled shafts), regardless of their method of installationprovided that they are receptive to low strain impact testing.1.2 This standard provides minimum requirements for lowstrain impact testing of piles. Pla

5、ns, specifications, and/orprovisions prepared by a qualified engineer, and approved bythe agency requiring the test(s), may provide additional re-quirements and procedures as needed to satisfy the objectivesof a particular test program.1.3 The text of this standard references notes and footnoteswhic

6、h provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 All observed and cal

7、culated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.6 The method used to specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses

8、, or both. How one applies the results obtained using thisstandard is beyond its scope.1.7 This standard may involve hazardous materials,operations, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the use

9、r of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1he quality of the result produced by this test method isdependent on the competence of the personnel performing it, and thesuitability of the equipment

10、 and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/ inspection/etc. Users of this test methodare cautioned that compliance with Practice D3740 does not in itselfassure reliable results. Reliable results d

11、epend on many factors; PracticeD3740 provides a means of evaluating some of those factors.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock a

12、sUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalData3. Terminology3.1 DefinitionsExcept as defined in 3.2, the terminologyused in this test method conforms with Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 pile integ

13、rity, nthe qualitative evaluation of thephysical dimensions, continuity of a pile, and consistency ofthe pile material.3.2.2 pile impedance, nthe dynamic Youngs modulus ofthe pile material multiplied by the applicable cross sectionalarea of the pile and divided by the strain wave speed.3.2.3 pulse e

14、cho method, ntest in which measurements ofthe pile head velocity and force (force measurement optional)are evaluated as a function of time.3.2.4 transient response method, ntest in which the ratioof velocity transform to force transform (force measurementrequired) are evaluated as a function of freq

15、uency.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.11 on Deep Foundations.Current edition approved Nov. 1, 2013. Published January 2014. Originallyapproved in 1995. Last previous edition approved in 2000 as D588

16、2 07. DOI:10.1520/D5882-07R13.2For 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.Copyright ASTM International, 1

17、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 Low strain impact integrity testing provides accelerationor velocity and force (optional) data on slender structuralelements (that is, structural columns, driven concrete piles, castin place

18、 concrete piles, concrete filled steel pipe piles, timberpiles, etc.). The method works best on solid concrete sections,and has limited application to unfilled steel pipe piles, H piles,or steel sheet piles.These data assist evaluation of pile integrityand pile physical dimensions (that is, cross-se

19、ctional area,length), continuity, and consistency of the pile material, al-though evaluation is approximate and not exact. This testmethod will not give information regarding the pile bearingcapacity.4.1.1 Methods of Testing:4.1.1.1 Pulse Echo Method (PEM)The pile head motion ismeasured as a functio

20、n of time. The time domain record is thenevaluated for pile integrity.4.1.1.2 Transient Response Method (TRM)The pile headmotion and force (measured with an instrumented hammer) aremeasured as a function of time. The data are evaluated usuallyin the frequency domain.5. Apparatus5.1 Apparatus for App

21、lying Impact:5.1.1 Impact Force ApplicationThe impact may be deliv-ered by any device (for example, a hand held hammer) that willproduce an input force pulse of generally less than 1 msduration and should not cause any local pile damage due to theimpact. A hammer with a very hard plastic tip can ind

22、uce ashort input force pulse without causing local pile damage. Theimpact should be applied axially to the pile (normally on thepile head).5.2 Apparatus for Obtaining Measurements:5.2.1 Velocity MeasurementObtain velocity data from in-tegration of signals from (one or more) accelerometers, pro-vided

23、 the acceleration signal(s) can be integrated to velocity inthe apparatus for reducing data. The accelerometer(s) shouldbe placed at (or near) the pile head and shall have theirsensitive axis parallel with the pile axis. Accelerometers shallbe linear to at least 50 g. EitherA/C or D/C accelerometers

24、 canbe used. If A/C devices are used, the time constant shall begreater than 0.5 s and the resonant frequency shall be at least30 000 Hz. If D/C devices are used, they shall have frequencyresponse up to 5 000 Hz with less than 3 dB reduction ofcontent. Alternatively, velocity or displacement transdu

25、cersmay be used to obtain velocity data, provided they areequivalent in performance to the specified accelerometers.Calibrate the transducer to an accuracy of 5 % throughout theapplicable measurement range. If damage is suspected duringuse, recalibrate or replace the accelerometer.5.2.2 Force Measur

26、ement (optional)The impact deviceshall be capable of measuring the impact force as a function oftime. The hammer may have a force load cell between the tipand hammer body. Alternatively, the hammer may have anaccelerometer attached and the measured acceleration may beconverted to force using the ham

27、mer mass. The force calibra-tion shall be within 5 %. The hammer must be tuned such thatthe fourrier transform of the measured force shall have asmooth spectrum, without any local peaks.5.2.3 Placement of TransducersThe motion sensor shouldbe placed at or near the pile head using a suitable, or temp

28、orary,thin layer of bonding material (that is, wax, vaseline, putty etc.)so that it is assured that it correctly measures the axial pilemotion (transducer axis of sensitivity aligned with the pileaxis). The motion sensor is placed generally near the center ofthe pile. Additional locations should be

29、considered for pileswith diameters greater than 500 mm. The low strain impactshould be applied to the pile head within a distance of 300 mmfrom the motion sensor. If the pile head is not accessible, aswhen already integral with the structure, the sensor(s) may beattached to the side of the pile shaf

30、t.5.3 Signal TransmissionThe signals from the sensors shallbe conveyed to the apparatus for recording, reducing, anddisplaying the data, see 5.4, by a low noise shielded cable orequivalent.5.4 Apparatus for Recording, Reducing and DisplayingData:5.4.1 GeneralThe signals from the motion and force(opt

31、ional) sensors, see 5.2, shall be conveyed to an apparatusfor recording, reducing, and displaying data as a function oftime. The apparatus shall include a graphic display of velocity(Fig. 1) and force (optional), and a data storage capability forretrieving records for further analysis. . The velocit

32、y displaycan be referenced either to the initial rise, as shown, or to thefirst peak.The apparatus should be capable of averaging data ofseveral blows to reinforce the repetitive information from soiland pile effects while reducing random noise effects. Theapparatus shall be able to apply increasing

33、 intensity amplifi-cation of the motion signal with time after the impact toenhance the interpretation of the measured motions that arereduced by soil and pile material damping. The apparatus musthave filtering capability with variable frequency limits foreliminating high frequency, or low frequency

34、 signalcomponents, or both. The apparatus shall be capable oftransferring all data to a permanent storage medium. TheFIG. 1 Typical Velocity Traces for the Pulse Echo Method Gener-ated by the Apparatus for Obtaining Dynamic Measurements(note the orientation of the input pulse is shown as positive in

35、this standard; orientation could also be shown negative)D5882 07 (2013)2apparatus shall allow for a permanent graphical output of therecords. A typical schematic arrangement for this apparatus isillustrated in Fig. 2.NOTE 2It is recognized that the velocity signal may be drawn in eitherdownward or u

36、pward positive amplitudes. The depth scale may be alignedeither at the start of the rise (as shown) or at the initial peak. It isrecommended that information be included in the plot showing themagnification function with time.5.4.2 Recording ApparatusAnalog signals from the mo-tion sensor must be di

37、rectly digitized using an analog to digitalconverter with at least 12 bit resolution (16 bit or higherresolution is preferred)such that signal components having alow pass cut-off frequency of 5 000 Hz (3dB) are retained.When digitizing, the sample frequency, therefore, shall be atleast 25 000 Hz eac

38、h for the motion sensor and the optionalinstrumented hammer, if used. The uniformity and accuracy ofthe digital sampling frequency is critical; the clock jitter(sampling frequency accuracy) must be within 0.01 %. Analogdata acquisition systems are specifically prohibited. Attachedto every digitized

39、event should be identifying informationnames and descriptions, signal processing enhancementparameters, and date and time stamps. The digital record shallbe permanently stored.5.4.3 Apparatus for Reducing DataThe apparatus forreducing signals from the transducers shall be a digital com-puter or micr

40、oprocessor capable of at least the followingfunctions:5.4.3.1 Velocity DataIf accelerometers are used (see5.2.2), the apparatus shall provide signal conditioning andintegrate acceleration to obtain velocity. The apparatus shallbalance the velocity signal to zero between impact events.5.4.3.2 Force M

41、easurementsThe apparatus shall providesignal conditioning and amplification, for the force measure-ments. The force output shall be balanced to zero betweenimpact events.5.4.3.3 Signal ConditioningThe force and velocity datashall have equal frequency response curves to avoid relativephase shifts and

42、 amplitude differences.5.4.4 Display ApparatusEnsure that the signals from thetransducers specified in 5.2.1 and 5.2.2 are displayed by meansof an apparatus, such as an LCD graphic display, such that thevelocity and force (optional) can be observed as a function oftime for each hammer blow. This app

43、aratus may receive thesignals after they have been processed by the apparatus forreducing the data.The apparatus shall display the digitized dataof the impact event or upon recall by the user of the digitallystored event.Adjust the apparatus to reproduce a signal havinga duration greater than 2L/c p

44、lus 5 milliseconds, where L is thepile length and c is the material wave speed.6. Procedure6.1 GeneralRecord applicable project information intothe apparatus when appropriate (Section 7). The appropriatemotion sensor (see 5.2) shall be attached to or pressed againstthe pile head. Record the measurem

45、ents from several impacts.Average the suitable records of at least three impacts and applynecessary amplification to the averaged record. The recordsfrom the individual impacts or the averaged record, or both,should then be stored (see 5.4.2). The averaged, amplifiedrecord then can be evaluated for

46、integrity.6.2 PreparationFor cast-in-place concrete piles or con-crete filled pipe piles, perform the integrity testing no soonerthan 7 days after casting or after concrete strength achieves atleast 75 % of its design strength, whichever occurs earlier.Ensure that the pile head surface is accessible

47、, above water,and clean of loose concrete, soil or other foreign materialsresulting from construction. If the pile head is contaminated,remove a sufficient pile section to reach sound concrete.Because proper pile top preparation is critical to the successfulapplication of this method, if necessary,

48、prepare small areas bya hand grinder to provide a smooth surface for motion sensorattachment and impact. Attach the motion sensor firmly to pile(i.e. solid contact) at selected locations away from the edge ofthe pile head. For piles with diameters larger than 500 mm,attach the accelerometer at a min

49、imum of three locations soFIG. 2 Schematic Diagram of Apparatus for Integrity TestingD5882 07 (2013)3that an integrity evaluation near the pile head may be made foreach localized section of pile. Position the apparatus forapplying the impact force so that the impact is applied axiallywith the pile and at a distance no larger than 300 mm from theaccelerometer. Set up the apparatus for recording, reducing,and displaying data so that it is operational and the force andvelocity signals are zeroed.6.3 Field NotesInclude the following information in de-tailed