1、Designation: D5882 16Standard 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 year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the procedure for determiningthe integrity of individual vertical or inclined piles by measur-ing and an
3、alyzing 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 simil
4、ar 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, specification
5、s, 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 explana
6、tory 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 sh
7、all 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, or both. How on
8、e 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 user of this standar
9、d 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 facilities u
10、sed. 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 depend on many fac
11、tors; 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 asUsed in Engineer
12、ing Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalDataD6760 Test Method for Integrity Testing of Concrete DeepFoundations by Ultrasonic Crosshole TestingD7949 Test Methods for Thermal Integrity Profiling ofConcrete Deep Foundations3. Terminology3.1 DefinitionsExce
13、pt 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 integrity, nthe qualitative evaluation of thephysical dimensions, continuity of a pile, and consistency ofthe pile material.3.2.2 pile impedance,
14、 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, ntest in which measurements ofthe pile head velocity and force (force measurement optional)are evaluated as a function of time.1
15、This 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 July 1, 2016. Published July 2016. Originally approvedin 1995. Last previous edition approved in 2013 as D5882 07(2013)
16、. DOI:10.1520/D5882-16.2For 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.*A Summary of Changes section appears
17、at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.4 transient response method, ntest in which the ratioof velocity transform to force transform (force measurementrequired) are evaluated as a function of fr
18、equency.4. 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 concrete piles, concrete filled steel pipe piles, timberpiles, etc.). The
19、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 the pilecross-sectional area and length, the pile integrity andcontinuity, as well as consistency of the pile material, althoughevaluat
20、ion is approximate. This test method will not provideinformation regarding the pile bearing capacity. It is generallyhelpful to consider the soil profile, construction method andsite records when evaluating data obtained by this method.Other useful information to consider and compare with resultsof
21、this test includes low strain integrity test results of similarpiles at the same site, concrete cylinder or core strength testresults, automated monitoring data on equipment placing theconcrete when augered piles are used, or information obtainedfrom crosshole sonic logging (Test Method D6760) or th
22、ermalintegrity profiling (Test Methods D7949) if available.4.1.1 Methods of Testing:4.1.1.1 Pulse Echo Method (PEM)The pile head motion ismeasured as a function of time. The time domain record is thenevaluated for pile integrity.4.1.1.2 Transient Response Method (TRM)The pile headmotion and force (m
23、easured with an instrumented hammer) aremeasured as a function of time. The data are evaluated usuallyin the frequency domain.5. Apparatus5.1 Apparatus for Applying Impact:5.1.1 Impact Force ApplicationThe impact may be deliv-ered by any device (for example, a hand held hammer) that willproduce an i
24、nput 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 causing local pile damage. Theimpact should be applied axially to the pile (normally on thepile head).5.
25、2 Apparatus for Obtaining Measurements:5.2.1 Velocity MeasurementObtain velocity data from in-tegration of signals from (one or more) accelerometers, pro-vided the acceleration signal(s) can be integrated to velocity inthe apparatus for reducing data. The accelerometer(s) shouldbe placed at (or near
26、) 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 time constant shall begreater than 0.5 s and the resonant frequency shall be at least30 000 Hz. If
27、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, provided they areequivalent in performance to the specified accelerometers.Calibrate the transducer
28、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 capable of measuring the impact force as a function oftime. The hammer may have a force load cell b
29、etween 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 within 5 %. The hammer must be tuned such thatthe fourrier transform of the measured force shall ha
30、ve 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, wax, vaseline, putty etc.)so that it is assured that it correctly measures the axial pilemotio
31、n (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 than 500 mm. The low strain impactshould be applied to the pile head within a distance of 300 mmfr
32、om 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 sensors shallbe conveyed to the apparatus for recording, reducing, anddisplaying the data, see
33、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 an apparatusfor recording, reducing, and displaying data as a function oftime. The apparatus sh
34、all 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 initial rise, as shown, or to thefirst peak.The apparatus should be capable of averaging data ofFIG.
35、 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 inthis standard; orientation could also be shown negative)D5882 162several blows to reinforce the repetitive information fr
36、om soiland pile effects while reducing random noise effects. Theapparatus shall be able to apply increasing 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 m
37、usthave filtering capability with variable frequency limits foreliminating high frequency, or low frequency signalcomponents, or both. The apparatus shall be capable oftransferring all data to a permanent storage medium. Theapparatus shall allow for a permanent graphical output of therecords. A typi
38、cal schematic arrangement for this apparatus isillustrated in Fig. 2.NOTE 2It is recognized that the velocity signal may be drawn in eitherdownward or 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 in
39、formation be included in the plot showing themagnification function with time.5.4.2 Recording ApparatusAnalog signals from the mo-tion sensor must be directly digitized using an analog to digitalconverter with at least 12 bit resolution (16 bit or higherresolution is preferred)such that signal compo
40、nents 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 hammer, if used. The uniformity and accuracy ofthe digital sampling frequency is critical; the
41、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 descriptions, signal processing enhancementparameters, and date and time stamps. The digital record
42、 shallbe permanently 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 followingfunctions:5.4.3.1 Velocity DataIf accelerometers are used (see5.2.2), the apparatus shall provide signal
43、 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 conditioning and amplification, for the force measure-ments. The force output shall be balanced to zero
44、 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 that the signals from thetransducers specified in 5.2.1 and 5.2.2 are displayed by meansof an a
45、pparatus, 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 processed by the apparatus forreducing the data.The apparatus shall display the digitized dataof
46、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 is the material wave speed.6. Procedure6.1 GeneralRecord applicable project information intothe
47、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 records of at least three impacts and applynecessary amplification to the averaged record. The record
48、sfrom 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 piles or con-crete filled pipe piles, perform the integrity testing no soonerthan 7 days after c
49、asting or after concrete strength achieves atFIG. 2 Schematic Diagram of Apparatus for Integrity TestingD5882 163least 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 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, prepare small areas bya hand grinder to p
