1、Designation: D5780 18Standard 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. Scope1.1 The test methods described in this standard measure theaxial deflection of a vertical or inclined deep foundation whenloaded in static axial compression. These methods apply to alldeep foundations, referred to herein as piles, th
5、at function in amanner similar to driven piles or cast-in-place piles, regardlessof their method of installation, and may be used for testingsingle piles or pile groups. The test results may not representthe long-term performance of a deep foundation.1.2 This standard provides minimum requirements f
6、or test-ing deep foundations under static axial compressive load.Plans, specifications, and/or provisions prepared by a qualifiedengineer may provide additional requirements and proceduresas needed to satisfy the objectives of a particular test program.The engineer in responsible charge of the found
7、ation design,referred to herein as the Engineer, shall approve anydeviations, deletions, or additions to the requirements of thisstandard.1.3 This standard allows the following test procedures:Procedure A Quick Test 8.1.2Procedure B Maintained Test(Optional)8.1.3Procedure C Loading in Excess ofMaint
8、ained Test(Optional)8.1.4Procedure D Constant Time IntervalTest (Optional)8.1.5Procedure E Constant Rate ofPenetration Test(Optional)8.1.6Procedure F Constant MovementIncrement Test(Optional)8.1.7Procedure G Cyclic Loading Test(Optional)8.1.81.4 Apparatus and procedures herein designated “optional”m
9、ay produce different test results and may be used only whenapproved by the Engineer. The word “shall” indicates amandatory provision, and the word “should” indicates arecommended or advisory provision. Imperative sentencesindicate mandatory provisions.1.5 A qualified geotechnical engineer should int
10、erpret thetest results obtained from the procedures of this standard so asto predict the actual performance and adequacy of piles used inthe constructed foundation. See Appendix X1 for commentsregarding some of the factors influencing the interpretation oftest results.1.6 A qualified engineer shall
11、design and approve all load-ing apparatus, loaded members, support frames, and testprocedures. The text of this standard references notes and1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.19 on Frozen Soils andRoc
12、k.Current edition approved Nov. 15, 2018. Published December 2018. Originallyapproved in 1995. Last previous edition approved in 2010 as D5780 10. DOI:10.1520/D5780_D5780M-18.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis interna
13、tional standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Commi
14、ttee.1footnotes which provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requirements of the standard. This standard alsoincludes illustrations and appendixes intended only for ex-planatory or advisory use.1.7 UnitsThe values stat
15、ed in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in non-conformance with the standard.1.8
16、The gravitational system of inch-pound units is usedwhen dealing with inch-pound units. In this system, the poundlbf represents a unit of force weight, while the unit for massis slugs. The rationalized slug unit is not given, unless dynamicF=ma calculations are involved.1.9 All observed and calculat
17、ed values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.10 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
18、 both. How one applies the results obtained using thisstandard is beyond its scope.1.11 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, health, and environment
19、al practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 9.1.12 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Pr
20、inciples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requ
21、irements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD5882 Test Method for Low Strain Impact Integrity Testingof Deep FoundationsD6026 Practice for Using Significant Digits in GeotechnicalDataD7099 Terminology Relating to Frozen Soil
22、 and Rock2.2 ANSI Standard:3B 30.1 Safety Code for Jacks3. Terminology3.1 Definitions:3.1.1 For definitions of terms 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 Th
23、is Standard:3.2.1 adfreeze bond strength, nthe strength of the bonddeveloped between frozen soil and the surface of the pile.3.2.2 base load, na load equivalent to the design loadadjusted for test pile geometry and expected ground tempera-ture.3.2.3 creep load, nthat load applied to measure a rate o
24、fdisplacement.3.2.4 creep load increment, nan incremental load appliedto a pile to determine the rate of displacement at 10 % of afailure load or at 100 % of a design load.3.2.5 design active layer, nthe maximum depth of annualthaw anticipated surrounding the pile under design conditions.3.2.6 failu
25、re (in piles), npile displacement that is occur-ring at an increasing rate with time under the action of aconstant load, incremental pile displacement that is increasingfor uniform time increments, or a creep rate which exceeds100 % of the design creep rate when loaded to 100 % of thedesign load.3.2
26、.7 failure load, nthat load applied to a pile to causefailure to occur.3.2.8 failure load increment, nthe load increment appliedto a pile that causes failure within a specified time period.3.2.9 freezeback, nfor the purpose of this test method,freezeback shall be defined as the attainment of a subfr
27、eezingtemperature at each ground temperature measuring point lo-cated below the design active layer, which have attainedequilibrium with the surrounding soil.3.2.10 ice-poor, nfrozen soil with a high solids concen-tration whose behavior is characterized mainly by soil particlecontacts.3.2.11 ice-ric
28、h, nfrozen soil with a moderate to low solidsconcentration whose behavior is characterized by ice particlecontacts.3.2.12 pile, driven, na pile driven into the ground with animpact or vibratory pile hammer.3.2.13 pile, grouted, na pile placed in an oversized,pre-drilled hole and backfilled with a sa
29、nd, cement grout.3.2.14 pile, slurried, na pile placed in an oversized,pre-drilled hole and backfilled with a soil/water slurry.3.2.15 subfreezing temperature, nany temperature belowthe actual freezing temperature of the soil water combinationbeing used.3.2.16 time to failure, nthe total time from t
30、he start of thecurrent test load increment to the point at which failure beginsto occur.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 Summa
31、ry 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 1824. Significance and Use4.1 This test method will provide a relationship betweentime to failure, creep rate, and displacement to failure f
32、orspecific 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-trolled by either limiting long-term stress to below long-terms
33、trength or by limiting allowable settlement over the design lifeof the structure. It is the purpose of this test method to providethe basic information from which the limiting strength orlong-term settlement may be evaluated by geotechnical engi-neers.4.3 Data derived from pile tests at specific gro
34、und tempera-tures that differ from the design temperatures must be correctedto the design temperature by the use of data from additionalpile tests, laboratory soil strength tests, or publishedcorrelations, if applicable, to provide a suitable means ofcorrection.4.4 For driven piles or grouted piles,
35、 failure will occur at thepile/soil interface. For slurry piles, failure can occur at eitherthe pile/slurry interface or the slurry/soil interface, dependingon the strength and deformation properties of the slurrymaterial and the adfreeze bond strength. Location of the failuresurface must be taken i
36、nto account in the design of the testprogram and in the interpretation of the test results. Dynamicloads must be evaluated separately.NOTE 1The quality of the results produced by application of thisstandard is dependent on the competence of the personnel performing it,and the suitability of the equi
37、pment and facilities. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depen
38、d 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 the procedures andspecifications used for the installation of the production piles.NOTE 2Because the pile behavior will be influenced by the soi
39、l type,temperature, ice content, and pore water salinity, the engineer must ensurethat adequate information is available for soil/ice conditions at theconstruction site to determine their effect on the pile performance (that is,test pile should be installed in the same condition as the productionpil
40、espreferably 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 onthe shaft of the pile. Address end bearing by measuring itseffect, eliminating its effect, or accounting for its effectanalytically. Measure e
41、nd bearing by attaching a load cell tothe tip of the pile prior to installation or by attaching a seriesof strain gauges along the length of the pile prior to installation.Eliminate end bearing by attaching a compressible layer to thetip of the pile prior to installation or by providing a voidbeneat
42、h 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 adjacent to the pile. Measure ground temperature infrozen ground at a minimum of three locations along the lengthof pile; for piles longer than
43、 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 withthe exterior pile surface; for slurry piles, installation may be asshown in Fig. 1; for driven piles, installation may be as shownin Fig. 2.5.4 M
44、easure ground temperatures periodically using theinstalled temperature-measuring devices to determine whenfreezeback occurs.5.5 Where freezeback of soils adjacent to the pile is aidedby the circulation of cold air or liquid coolant, discontinue suchcooling when the measured ground temperatures becom
45、e equalto the desired ground temperature for the pile test; significantovercooling shall not be permitted to occur. When freezebackof soils adjacent to 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
46、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 layer. This maybe accomplished by using a sleeve or casing. For slurried piles,FIG. 1 Placement of Temperature Measuring Devices for SlurryTest PileD578
47、0 183a 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 area of the testpile or fill to the proposed finished grade elevation.
48、 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 necessary, brace theunsupported length of the test pile(s) to prevent bu
49、cklingwithout influencing the test results.5.8 If the top of the pile has been damaged duringinstallation, remove the damaged portion prior to the test.NOTE 3Consideration 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 test pile to adistance of 5 ft 1.5 m, two times the depth of thawed soil or one third ofthe installed pile length, whichever is greater. The
