ASTM D7383-2008 431 Standard Test Methods for Axial Compressive Force Pulse (Rapid) Testing of Deep Foundations.pdf

1、Designation: D 7383 08Standard Test Methods forAxial Compressive Force Pulse (Rapid) Testing of DeepFoundations1This standard is issued under the fixed designation D 7383; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of

2、 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 These test methods cover procedures for testing anindividual vertical or inclined deep foundation to determine thedis

3、placement response to an axial compressive force pulseapplied at its top. These test methods apply to all deepfoundation units, referred to herein as “piles,” that function ina manner similar to driven or cast-in-place piles, regardless oftheir method of installation.1.2 Two alternative procedures a

4、re provided:1.2.1 Procedure A uses a combustion gas pressure apparatusto produce the required axial compressive force pulse.1.2.2 Procedure B uses a cushioned drop mass apparatus toproduce the required axial compressive force pulse.1.3 This standard provides minimum requirements for test-ing deep fo

5、undations under an axial compressive force pulse.Plans, specifications, provisions (or combinations thereof)prepared by a qualified engineer, may provide additionalrequirements and procedures as needed to satisfy the objectivesof a particular deep foundation test program. The engineer inresponsible

6、charge of the foundation design, referred to hereinas the “Engineer”, shall approve any deviations, deletions, oradditions to the requirements of this standard.1.4 The proper conduct and evaluation of force pulse testingrequires special knowledge and experience. A qualified engi-neer should directly

7、 supervise the acquisition of field data andthe interpretation of the test results so as to predict the actualperformance and adequacy of deep foundations used in theconstructed foundation. A qualified engineer shall approve theapparatus used for applying the force pulse, rigging andhoisting equipme

8、nt, support frames, templates, and test proce-dures.1.5 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard. The word “shall” indicates aman

9、datory provision, and the word “should” indicates arecommended or advisory provision. Imperative sentencesindicate mandatory provisions.1.6 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.7 All observed and calculated values s

10、hall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.8 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 the design orother uses, or both. H

11、ow one uses the results obtained usingthis standard is beyond its scope.1.9 ASTM International takes no position respecting thevalidity of any patent rights asserted in connection with anyitem mentioned in this standard. Users of this standard areexpressly advised that determination of the validity

12、of any suchpatent rights, and the risk of infringement of such rights, areentirely their own responsibility.1.10 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 r

13、esponsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Section 7 provides a partial list of specific hazards andprecautions.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Rel

14、ating to Soil, Rock, and ContainedFluidsD 1143 Test Method for Piles Under Static Axial Compres-sive Load3D 3689 Test Methods for Deep Foundations Under StaticAxial Tensile LoadD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engine

15、ering Design and Construction1These test methods are under the jurisdiction of ASTM Committee D18 on Soiland Rock and is the direct responsibility of Subcommittee D18.11 on DeepFoundations.Current edition approved Oct. 1, 2008. Published October 2008.2For referenced ASTM standards, visit the ASTM we

16、bsite, 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.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM

17、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 5882 Test Method for Low Strain Impact Integrity Test-ing of Deep FoundationsD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6760 Test Method for Integrity Testing of Concrete De

18、epFoundations by Ultrasonic Crosshole Testing3. Terminology3.1 Definitions:3.1.1 For common definitions of terms used in this standard,see Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 cast-in-place pile, na deep foundation unit made ofcement grout or concrete and constr

19、ucted in its final location,for example, drilled shafts, bored piles, caissons, augercastpiles, pressure-injected footings, etc.3.2.2 deep foundation, na relatively slender structuralelement (length greater than width) that transmits some or allof the load it supports to soil or rock well below the

20、groundsurface. It may be a driven pile, a cast-in-place pile, or analternate structural element having a similar function.3.2.3 driven pile, na deep foundation unit made of pre-formed material with a predetermined shape and size andtypically installed by impact hammering, vibrating, or pushing.3.2.4

21、 force pulse, nfor the purposes of this standard, a“force pulse” shall result in a force-time event similar to Fig. 1,typically reaching a target peak force. The applied force shallexceed the pre-load for a duration time of at least twelve timesthe test pile length (L) divided by the strain wave spe

22、ed ( c), or12L/c. The applied force shall also exceed 50 % of the actualpeak force for a minimum duration time of four times L/c. Theforce pulse shall increase smoothly and continuously to thepeak force and then decrease smoothly and continuously.Typical force pulse durations range from 90 to 250 ms

23、.NOTE 1A force pulse duration of less that 12L/c may be acceptable tothe Engineer when using supplemental transducers as described in 5.4.3.2.5 pre-load, nthe load applied to the pile head due tothe static weight of the test apparatus prior to the test, possiblynegligible depending on the design of

24、the test apparatus.3.2.6 target peak force, na pre-determined target value forthe desired amplitude of the force pulse as defined by theproject requirements. This value should typically exceed thesum of the required ultimate axial compressive static capacityplus the dynamic resistance of the pile by

25、 an amount deter-mined by the Engineer based on factors including, but notlimited to, pile type, soil type, structural strength of the pile,type of structural load, physical restrictions, or other projectrequirements (see Section 4).3.2.7 wave speed, c, nthe speed with which a strain wavepropagates

26、through a pile. It is a property of the pile compo-sition and is represented herein by c. For one-dimensionalwave propagation, c is equal to the square root of ElasticModulus divided by mass density: c =(E/r)1/2. Typical valuesof c are 4000 m/s for concrete piles and 5100 m/s for steelpiles.4. Signi

27、ficance and Use4.1 Based on the measurements of force and displacement atthe pile top, possibly combined with those from acceleration orstrain transducers located further down the pile, these testmethods measure the pile top deflection in response to an axialcompressive force pulse. The relatively l

28、ong duration of theforce pulse compared to the natural period of the test pileFIG. 1 Typical Axial Compressive Force PulseD7383082causes the pile to compress and translate approximately as aunit during a portion of the pulse, simultaneously mobilizingcompressive axial static capacity and dynamic res

29、istance at allpoints along the length of the pile for that portion of the test.The Engineer may analyze the acquired data using engineeringprinciples and judgment to evaluate the performance of theforce pulse apparatus, and the characteristics of the pilesresponse to the force pulse loading.4.2 If s

30、ignificant permanent axial movement occurs duringthe axial force pulse event, the Engineer may analyze theresults of the test to estimate, after assessing inertial effects andthe dynamic soil and rock response along the side and bottomof the pile, the ultimate axial static compression capacity (seeN

31、ote 2). The scope of this standard does not include analysisfor either ultimate or design foundation capacity. Factors thatmay affect the axial static capacity estimated from force pulsetests include, but are not limited to, the: (1) pile installationequipment and procedures, (2) elapsed time since

32、initialinstallation, (3) pile material properties and dimensions, (4)type, density, strength, stratification, and saturation of the soil,or rock, or both adjacent to and beneath the pile, (5) quality offorce pulse test data, (6) foundation settlement, (7) analysismethod, and (8) engineering judgment

33、 and experience. If theEngineer does not have adequate previous experience withthese factors, and with the analysis of force pulse test data, thena static load test carried out according to Test Method D 1143should be used to verify estimates of static capacity and itsdistribution along the pile len

34、gth. Test Method D 1143 providesa direct and more reliable measurement of static capacity.NOTE 2If a force pulse test produces insufficient axial movement,subsequent analysis may overestimate the static capacity because ofdifficulty in separating the static and dynamic components of the response.The

35、 analysis of a force pulse test to estimate static capacity also typicallyincludes a reduction factor to account for the additional load resistancethat occurs as a result of a faster rate of loading than used during a statictest. Force pulse test results from cohesive soils generally require a great

36、erreduction factor due to the rate of loading effect, chosen conservatively toproduce a lower static capacity estimate. The Engineer should determinehow the type, size, and shape of the pile, and the properties of the soil orrock beneath and adjacent to the pile, affect the rate-of-loading reduction

37、factors and the amount of movement required to mobilize and accuratelyassess the static capacity. Correlations between actual measurements andforce pulse estimates of the ultimate axial static compression capacitygenerally improve when using additional transducers embedded in thepile. Static capacit

38、y may also change over time after the pile installation,especially for driven piles. Both static and force pulse tests represent thecapacity at the time of the respective test, and correlation attempts shouldprovide results for a similar time of testing after pile installation or includeanalysis to

39、account for changes in the soil strength during the timebetween the two tests.4.3 When used in conjunction with additional transducersembedded in the pile, these test methods may also be used tomeasure the pile response to the axial force pulse along the pilelength. When combined with an appropriate

40、 method of analy-sis, the Engineer may use data from these optional transducersto estimate the relative contribution of side shear and endbearing to the mobilized axial static compressive capacity ofthe pile, or to infer the relative contribution of certain soillayers to the overall axial compressiv

41、e capacity of the pile.NOTE 3When used in conjunction with additional transducers embed-ded in the pile the force pulse test analysis may provide an estimate of thepiles tension (uplift) capacity. Users of this standard are cautioned tointerpret the estimated side resistance conservatively. If the E

42、ngineer doesnot have adequate previous experience for the specific site and pile typewith the analysis of force pulse test data for tension capacity, then a staticload test carried out according to Test Method D 3689 should be used toverify tension capacity estimates. Test Method D 3689 provides a d

43、irectand more reliable measurement of static tension capacity.NOTE 4The quality of the result produced by these test methods isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D 3740 are ge

44、nerally considered capable of competentand objective testing and inspection. Users of these test methods arecautioned that compliance with Practice D 3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D 3740provides a means of evaluating some of those f

45、actors.5. Apparatus5.1 GeneralAny apparatus capable of applying a forcepulse to a pile foundation that is in accordance with Section 3shall be considered acceptable. The apparatus selected shall becapable of applying a target peak force in accordance with theproject requirements. This section descri

46、bes two specific typesof equipment used to generate an axial compressive forcepulse: a combustion gas pressure apparatus as shown in Fig. 2and a cushioned drop-mass apparatus as shown in Fig. 3.5.2 Combustion Gas Pressure Apparatus (for Procedure A):5.2.1 Piston and cylinder jack capable of confinin

47、g theoperating pressure, and capable of centering the force pulseapplication to the pile.5.2.2 Fuel and ignition mechanism to create gas pressure inthe combustion chamber.5.2.3 Reaction beam, supported by cylinder portion of jackto transfer the combustion force to the inertial or other reactionsyste

48、m.5.2.4 Reaction mass or other means to resist the combustionforces. A reaction mass system will typically weigh between 5and 15 % of the target peak force and will be comprised ofconcrete, steel or contained water.5.2.5 Accumulator or plenum to receive the combustion gas.5.2.6 Venting apparatus for

49、 the release of combustion gasfrom the plenum.5.2.7 Silencer apparatus to muffle the noise of the ventingcombustion gas.5.2.8 Means or mechanism to protect the pile from damagecaused by the fall of the reaction mass system (this willtypically consist of a gravel-filled enclosure or a mechanismfor arresting the reaction mass such as a hydraulic or mechani-cal system).5.2.9 Means or mechanism such as a rupture valve or disk torelease the combustion gas in the event of an accidentalincrease in system pressure or malfunction of the system.5.3 Cushioned Drop Mass Apparatus (fo