1、Designation: D5780 10Standard Test Methods forIndividual Piles in Permafrost Under Static AxialCompressive Load1This standard is issued under the fixed designation D5780; 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.INTRODUCTIONThese test methods have been prepared to cover methods of axial load testing of piles in permafrost.The provisions per
3、mit the introduction of more detailed requirements and procedures when requiredto satisfy the objectives of the test program. The procedures herein produce a relationship betweenapplied load and pile settlement for conditions of ground temperature at the time of test. The resultsmay be interpreted t
4、o establish long-term load capacity of piles in permafrost.1. Scope*1.1 These test methods cover procedures for testing indi-vidual vertical piles to determine response of the pile to staticcompressive load applied axially to the pile. These testmethods are applicable to all deep foundation units in
5、 perma-frost that function in a manner similar to piles regardless oftheir method of installation. This standard is divided into thefollowing sections:SectionReferenced Documents 2Terminology 3Significance and Use 4Installation of Test Piles 5Apparatus for Applying Loads 6Apparatus for Measuring Mov
6、ements 7Safety Requirements 8Loading Procedures 9Standard Test Procedures 10Procedures for Measuring Pile Movements 11Report 12Precision and Bias 13Keywords 14NOTE 1Apparatus and procedures designated “optional” are to berequired only when included in the project specifications or if notspecified, m
7、ay be used only with the approval of the engineer responsiblefor the foundation design. The word “shall” indicates a mandatoryprovision and “should” indicates a recommended or advisory provision.Imperative sentences indicate mandatory provisions. Notes, illustrations,and appendixes included herein a
8、re explanatory or advisory.NOTE 2This standard does not include the interpretation of test resultsor the application of test results to foundation design. See Appendix X1for comments regarding some of the factors influencing the interpretationof test results. A qualified geotechnical engineer should
9、 interpret the testresults for predicting pile performance and capacity.1.2 Three different test methods are included within thisstandard. Method A is the standard method combining theresults from loading two separate piles with the possibility ofa third alternate pile. Method B is the alternate met
10、hodcombining the results from loading three separate piles with thepossibility of a fourth alternate pile. Method C is a confirma-tion method requiring the testing of one pile with the possibil-ity of a second alternate. Method C is applicable only whereprior data are available.1.3 All recorded and
11、calculated values shall conform to theguide for significant digits and rounding established in PracticeD6026.1.3.1 The procedures used to specify how data are collected/recorded and calculated in this standard are regarded as theindustry standard. In addition, they are representative of thesignifica
12、nt digits that should generally be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives, and it is common practice toincrease or reduce significant digits of reported data to becomme
13、nsurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.19 on Frozen S
14、oils andRock.Current edition approved Feb. 1, 2010. Published March 2010. Originallyapproved in 1995. Last previous edition approved in 2002 as . DOI: 10.1520/D5780-10.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
15、 West Conshohocken, PA 19428-2959, United States.1.3.2 Measurements made to more significant digits orbetter sensitivity than specified in this standard shall not beregarded a nonconformance with this standard.1.4 The values stated in inch-pound units are to be regardedas the standard, except as not
16、ed below. The values given inparentheses are mathematical conversions to SI units, whichare provided for information only and are not consideredstandard.1.4.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units. In this system, the pound(lbf) represents a unit of f
17、orce (weight), while the unit for massis the slug.1.4.2 The slug unit of mass is almost never used incommercial practice. Therefore, the standard unit for mass inthis standard is either kilogram (kg) or gram (g), or both. Theequivalent inch-pound unit (slug) is not given in parentheses.1.4.3 It is c
18、ommon practice in the engineering/constructionprofession, in the United States, to concurrently use pounds torepresent both a unit of mass (lbm) and of force (lbf). Thisimplicitly combines two separate systems of units: that is, theabsolute system and the gravitational system. It is scientificallyun
19、desirable to combine the use of two separate sets ofinch-pound units within a single standard. As stated, thisstandard includes the gravitational system of inch-pound unitsand does not use/present the slug unit for mass. However, theuse of balances or scales recording pounds of mass (lbm) orrecordin
20、g density in lbm/ft3) shall not be regarded as noncon-formance with this standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and d
21、etermine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing
22、and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalDataD7099 Terminology Relating to Frozen Soil and Rock2.2 ANSI Standard:3B 30.1 Safety Code for Jacks3. Terminology3.1 Definitions:3.1.1 For definitions of terms
23、 relating to soil and rockmechanics refer to Terminology D653.3.1.2 For definitions for terms related to frozen ground referto Terminology D7099.3.2 Definitions of Terms Specific to This Standard:3.2.1 adfreeze bond strengththe strength of the bonddeveloped between frozen soil and the surface of the
24、 pile.3.2.2 base loada load equivalent to the design loadadjusted for test pile geometry and expected ground tempera-ture.3.2.3 creep loadthat load applied to measure a rate ofdisplacement.3.2.4 creep load incrementan incremental load applied toa pile to determine the rate of displacement at 10 % of
25、 a failureload or at 100 % of a design load.3.2.5 design active layerthe maximum depth of annualthaw anticipated surrounding the pile under design conditions.3.2.6 failure (in piles)pile displacement that is occurringat an increasing rate with time under the action of a constantload, incremental pil
26、e displacement that is increasing foruniform time increments, or a creep rate which exceeds 100 %of the design creep rate when loaded to 100 % of the designload.3.2.7 failure loadthat load applied to a pile to causefailure to occur.3.2.8 failure load incrementthe load increment applied toa pile that
27、 causes failure within a specified time period.3.2.9 freezebackfor the purpose of this test method, free-zeback shall be defined as the attainment of a subfreezingtemperature at each ground temperature measuring point lo-cated below the design active layer, which have attainedequilibrium with the su
28、rrounding soil.3.2.10 ice-poorfrozen soil with a high solids concentra-tion whose behavior is characterized mainly by soil particlecontacts.3.2.11 ice-richfrozen soil with a moderate to low solidsconcentration whose behavior is characterized by ice particlecontacts.3.2.12 pile, drivena pile driven i
29、nto the ground with animpact or vibratory pile hammer.3.2.13 pile, grouteda pile placed in an oversized, pre-drilled hole and backfilled with a sand, cement grout.3.2.14 pile, slurrieda pile placed in an oversized, pre-drilled hole and backfilled with a soil/water slurry.3.2.15 subfreezing temperatu
30、reany temperature below theactual freezing temperature of the soil water combination beingused.3.2.16 time to failurethe total time from the start of thecurrent test load increment to the point at which failure beginsto occur.4. Significance and Use4.1 This test method will provide a relationship be
31、tweentime to failure, creep rate, and displacement to failure forspecific failure loads at specific test temperatures as well as arelationship between creep rate and applied load at specific testtemperatures for loads less than failure loads.4.2 Pile design for specific soil temperatures may be con-
32、trolled by either limiting long-term stress to below long-termstrength or by limiting allowable settlement over the design lifeof the structure. It is the purpose of this test method to provide2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at se
33、rviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.D5780 102the basic information from which
34、 the limiting strength orlong-term settlement may be evaluated by geotechnical engi-neers.4.3 Data derived from pile tests at specific ground tempera-tures that differ from the design temperatures must be correctedto the design temperature by the use of data from additionalpile tests, laboratory soi
35、l strength tests, or published correla-tions, if applicable, to provide a suitable means of correction.4.4 For driven piles or grouted piles, failure will occur at thepile/soil interface. For slurried piles, failure can occur at eitherthe pile/slurry interface or the slurry/soil interface, depending
36、on the strength and deformation properties of the slurrymaterial and the adfreeze bond strength. Location of the failuresurface must be taken into account in the design of the testprogram and in the interpretation of the test results. Dynamicloads must be evaluated separately.NOTE 3The quality of th
37、e results produced by application of thisstandard is dependent on the competence of the personnel performing it,and the suitability of the equipment and facilities. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection
38、/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.5. Installation of Test Pile(s)5.1 Install the test pile according to t
39、he procedures andspecifications used for the installation of the production piles.NOTE 4Because the pile behavior will be influenced by the soil type,temperature, ice content, and pore water salinity, the engineer must ensurethat adequate information is available for soil/ice conditions at theconstr
40、uction site to determine their effect on the pile performance (that is,test pile should be installed in the same condition as the productionpilespreferably at the same site).5.2 The design and installation of the test pile shall addressthe effects of end bearing, as opposed to the shear resistance o
41、nthe shaft of the pile. Address end bearing by measuring itseffect, eliminating its effect, or accounting for its effectanalytically. Measure end bearing by attaching a load cell tothe tip of the pile prior to installation or by attaching a seriesof strain gages along the length of the pile prior to
42、 installation.Eliminate end bearing by attaching a compressible layer to thetip of the pile prior to installation or by providing a voidbeneath the tip of the pile.5.3 Install thermistors or other temperature-measuring de-vices adjacent to the test pile to determine the ground tempera-ture profile a
43、djacent to the pile. Measure ground temperature infrozen ground at a minimum of three locations along the lengthof pile; for piles longer than 10 ft (3 m), it is recommended thatground temperatures be measured at 5-ft (1.5-m) depth inter-vals. Install the temperature-measuring devices in contact wit
44、hthe exterior pile surface; for slurried piles, installation may beas shown in Fig. 1; for driven piles, installation may be asshown in Fig. 2.5.4 Measure ground temperatures periodically using theinstalled temperature-measuring devices to determine whenfreezeback occurs.5.5 Where freezeback of soil
45、s adjacent to the pile is aidedby the circulation of cold air or liquid coolant, discontinue suchcooling when the measured ground temperatures become equalto the desired ground temperature for the pile test; significantovercooling shall not be permitted to occur. When freezebackof soils adjacent to
46、the test piles is aided by a designed coolingsystem, such designed cooling system shall also be applied ina similar manner to all reaction piles to ensure freezeback ofthe reaction piles.5.6 Isolate the surface of the test pile from the surroundingsoil or ice over the depth of the design active laye
47、r. This maybe accomplished by using a sleeve or casing. For slurried piles,a greased wrapping or other technique that will essentiallyeliminate the transfer of shear forces between the pile and thesurrounding soil/ice in the design active layer may be used.5.7 Where feasible, excavate the immediate
48、area of the testpile or fill to the proposed finished grade elevation. Cut off testpiles or build up to the proper grade necessary to permitconstruction of the load-application apparatus, placement ofthe necessary testing and instrumentation equipment, andobservation of the instrumentation. Where ne
49、cessary, brace theunsupported length of the test pile(s) to prevent bucklingwithout influencing the test results.5.8 If the top of the pile has been damaged during installa-tion, remove the damaged portion prior to the test.FIG. 1 Placement of Temperature Measuring Devices for SlurriedTest PileD5780 103NOTE 5Consideration should be given to placing insulation on theground surface around the test pile in order to reduce the variation inground temperatures with time during the testing period. Where used,ground surface insulation should be placed all around the
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1