ASTM D5882-2007 Standard Test Method for Low Strain Impact Integrity Testing of Deep Foundations《深层地基的低应变冲击完整性测试用标准试验方法》.pdf

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1、Designation: D 5882 07Standard Test Method forLow Strain Impact Integrity Testing of Deep Foundations1This standard is issued under the fixed designation D 5882; 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 (e) 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 measur-ing and

3、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 in a manner sim

4、ilar 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. Plans, specificati

5、ons, 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 footnoteswhich provide expla

6、natory 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 calculated values

7、shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.6 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, or both. How

8、 one applies the results obtained using thisstandard is beyond its scope.1.7 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this st

9、andard 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 and facilit

10、ies used. Agencies that meet thecriteria of Practice D 3740 are generally considered capable of competentand objective testing/sampling/ inspection/etc. Users of this test methodare cautioned that compliance with Practice D 3740 does not in itselfassure reliable results. Reliable results depend on m

11、any factors; PracticeD 3740 provides a means of evaluating some of those factors.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Us

12、ed in Engineering Design and ConstructionD 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 Except as defined in 3.2, the terminology used in thistest method conforms with Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 pile integrity, nthe

13、 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 echo method

14、, 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 frequency.4. S

15、ignificance 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 concrete piles, concrete filled steel pipe piles, timber1This test method is under the

16、 jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.11 on Deep Foundations.Current edition approved May 1, 2007. Published June 2007. Originallyapproved in 1995. Last previous edition approved in 2000 as D 588200.2For referenced ASTM standards, vis

17、it 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2

18、959, United States.piles, 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-sectional area,length), continuity, and

19、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 Testing4.1.1.1 Pulse Echo Method (PEM)The pile head motionis measured as a function of time. The time domain record isthe

20、n evaluated 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 Applying Impact5.1.1 Impact Force Applicat

21、ionThe 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 induce ashort input force pulse without cau

22、sing local pile damage. Theimpact should be applied axially to the pile (normally on thepile head).5.2 Apparatus for Obtaining Measurements5.2.1 Velocity MeasurementObtain velocity data fromintegration of signals from (one or more) accelerometers,provided the acceleration signal(s) can be integrated

23、 to velocityin the 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 canbe used. If A/C devices are used, the tim

24、e 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 transducersmay be used to obtain velocity data, prov

25、ided 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 Measurement (optional)The impact deviceshall be cap

26、able 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 hammer mass. The force calibra-tion shall be wit

27、hin 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 temporary,thin layer of bonding material (that is

28、, 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 considered for pileswith diameters greater th

29、an 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 shaft.5.3 Signal TransmissionThe signals from the

30、 sensorsshall be 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(optional) sensors, see 5.2, shall be conveyed to

31、 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 velocity displaycan be referenced either to the init

32、ial 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 intensity amplifi-cation of the motion signa

33、l 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 signal compo-nents, or both.The apparatus sh

34、all be capable of transferring alldata to a permanent storage medium. The apparatus shall allowfor a permanent graphical output of the records. A typicalschematic arrangement for this apparatus is illustrated in Fig. 2.NOTE 2It is recognized that the velocity signal may be drawn in eitherdownward or

35、 upward 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.FIG. 1 Typical Velocity Traces for the Pulse Echo MethodGenerated by the

36、 Apparatus for Obtaining DynamicMeasurements (note the orientation of the input pulse is shownas positive in this standard; orientation could also be shownnegative)D58820725.4.2 Recording ApparatusAnalog signals from the mo-tion sensor must be directly digitized using an analog to digitalconverter w

37、ith 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 each for the motion sensor and the optionalinstrumented h

38、ammer, 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 event should be identifying informationnames and descr

39、iptions, signal processing enhancement param-eters, and date and time stamps. The digital record shall bepermanently stored.5.4.3 Apparatus for Reducing DataThe apparatus forreducing signals from the transducers shall be a digital com-puter or microprocessor capable of at least the followingfunction

40、s: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 MeasurementsThe apparatus shall providesignal conditi

41、oning 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 amplitude differences.5.4.4 Display ApparatusEnsure

42、 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 apparatus may receive thesignals after they have been p

43、rocessed 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 plus 5 milliseconds, where L is thepile length and c

44、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 measurements from several impacts.Average the suitable recor

45、ds 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 integrity.6.2 PreparationFor cast-in-place concrete

46、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, above water,and clean of loose concrete, soil or o

47、ther 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, prepare small areas bya hand grinder to provide a sm

48、ooth 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 minimum of three locations sothat an integrity evaluati

49、on 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 records, as available, for each pile tested.FIG. 2 Schematic Diagram of Apparatus for Integrity TestingD58820736.3.1 Pile identifica