ASTM D5780-1995(2002) Standard Test Method for Individual Piles in Permafrost Under Static Axial Compressive Load《静态轴向压缩加载下永冻层中各个叠层的标准试验方法》.pdf

《ASTM D5780-1995(2002) Standard Test Method for Individual Piles in Permafrost Under Static Axial Compressive Load《静态轴向压缩加载下永冻层中各个叠层的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D5780-1995(2002) Standard Test Method for Individual Piles in Permafrost Under Static Axial Compressive Load《静态轴向压缩加载下永冻层中各个叠层的标准试验方法》.pdf（14页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 5780 95 (Reapproved 2002)Standard Test Method forIndividual Piles in Permafrost Under Static AxialCompressive Load1This standard is issued under the fixed designation D 5780; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev

2、ision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONThis test method has been prepared to cover methods of axial load testing of piles in permafrost.

3、Theprovisions permit the introduction of more detailed requirements and procedures when required tosatisfy 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

4、 be interpreted to establish long-term load capacity of piles in permafrost.1. Scope1.1 This test method covers procedures for testing indi-vidual vertical piles to determine response of the pile to staticcompressive load applied axially to the pile. This test methodis applicable to all deep foundat

5、ion units in permafrost thatfunction in a manner similar to piles regardless of their methodof installation. This test method is divided into the followingsections:SectionReferenced Documents 2Terminology 3Significance and Use 4Installation of Test Piles 5Apparatus for Applying Loads 6Apparatus for

6、Measuring Movements 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 no

7、tspecified, may 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 incl

8、uded herein are explanatory or advisory.NOTE 2This test method does not include the interpretation of testresults or the application of test results to foundation design. SeeAppendix X1 for comments regarding some of the factors influencing theinterpretation of test results. A qualified geotechnical

9、 engineer shouldinterpret the test results for predicting pile performance and capacity.1.2 The values stated in inch-pound units are to be regardedas the standard. The SI units given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if a

10、ny, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 8.2. Referenced Documents2.1 ASTM S

11、tandards:D 653 Terminology Relating to Soil, Rock, and ContainedFluids22.2 ANSI Standard:B 30.1 Safety Code for Jacks33. Terminology3.1 Definitions:3.1.1 The standard definitions of terms and symbols relatingto soil and rock mechanics is Terminology D 653.3.2 Definitions of Terms Specific to This St

12、andard:3.2.1 adfreeze bond strengththe strength of the bonddeveloped between frozen soil and the surface of the pile.3.2.2 base loada load equivalent to the design loadadjusted for test pile geometry and expected ground tempera-ture.1This test method is under the jurisdiction of ASTM Committee D18 o

13、n Soil andRock and is the direct responsibility of Subcommittee D18.19 on Frozen Soils andRock.Current edition approved Sept. 10, 1995. Published January 1996.2Annual Book of ASTM Standards, Vol 04.08.3Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036

14、.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 a fai

15、lureload 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 pile disp

16、lacement 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 cause

17、s 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 surround

18、ing 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 into th

19、e 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 temperatureany

20、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 betweent

21、ime 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-trolle

22、d 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 providethe basic information from which the limiting strength orlong-term settlement may be evaluated by geotechnical en

23、gi-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 soil strength tests, or published correla-tions, if applicable, to provide a suitabl

24、e 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, dependingon the strength and deformation properties of the slurrymaterial and the adfreeze

25、 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.5. Installation of Test Pile(s)5.1 Install the test pile according to the procedures andspecifications u

26、sed for the installation of the production piles.NOTE 3Because 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 theconstruction site to determine their ef

27、fect 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 onthe shaft of the pile. Address e

28、nd 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 installation.Eliminate end beari

29、ng 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 adjacent to the pile. Measure grou

30、nd 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 withthe exterior pile surface; for s

31、lurried 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 soils adjacent to the pile is aidedby

32、 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 the test piles is aided by a desi

33、gned 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 layer. This maybe accomplished by usi

34、ng 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 area of the testpile or fill to t

35、he proposed finished grade elevation. Cut off testpiles or build up to the proper grade necessary to permitD 5780 95 (2002)2construction of the load-application apparatus, placement ofthe necessary testing and instrumentation equipment, andobservation of the instrumentation. Where necessary, brace t

36、heunsupported 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.NOTE 4Consideration should be given to placing insulation on theground surface around the te

37、st 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 g

38、reater. The effect of insulation atthe surface should be taken into account in the design of production piles,which could be done analytically.5.9 Allow the lateral normal stresses between the pilesurface and the surrounding soil that develop during pileinstallation or freezeback, or both, to dissip

39、ate to a nominallevel prior to pile testing. For purposes of this test method, thedelay time corresponding to the approximate test conditionfrom Table 1 shall be permitted to occur prior to commencingload application to allow for the dissipation of normal stresseson the pile shaft as discussed above

40、.NOTE 5The engineer may direct that delay times other than thoseshown in Table 1 be implemented, based on other completed pile testresults, laboratory test results, or analytical results. Such other timeinterval shall allow for the dissipation of normal stresses developed due topile installation or

41、freezeback, or both, to a level of 1 % or less of theirmaximum value.6. Apparatus for Applying Loads6.1 General:6.1.1 The apparatus for applying compressive loads to thetest pile shall be as described in 6.3, 6.4, or 6.5, or as otherwisespecified and shall be constructed so that the loads are applie

42、dto the central longitudinal axis of the pile to minimize eccentricloading. Subsections 6.3-6.5 are suitable for applying axialloads to individual vertical piles.FIG. 1 Placement of Temperature Measuring Devices for SlurriedTest PileFIG. 2 Potential Placement of Temperature Measuring Devices forDriv

43、en Structural-Shaped Test PileTABLE 1 Minimum Delay Times (Days After Freezeback)PermafrostConditionGround Temperature, F (C)Delay Times, DaysDriven Piles Slurried PilesIce-poor above 28 (2) 10 1423 to 28 (2 to 5) 5 7below 23 (5) 2 3Ice-rich above 28 (2) 14 2023 to 28 (2 to 5) 7 10below 23 (5) 5 7D

44、5780 95 (2002)3NOTE 6Consideration should be given to providing sufficient clearspace between the pile cap and the ground surface to eliminate any supportof the cap by the soil. A properly constructed steel grillage may serve asan adequate pile cap for testing purposes.6.1.2 For testing an individua

45、l pile, center a steel-bearingplate(s) on the pile and set perpendicular to the longitudinalaxis of the pile. It shall be of sufficient thickness to prevent itfrom bending under the loads involved (but not less than 2 in.(50 mm) thick). The size of the test plate shall be not less thanthe size of th

46、e pile top nor less than the area covered by thebase(s) of the hydraulic jack(s).6.1.3 For tests on precast or cast-in-place concrete piles, setthe test plate, when used, in high-strength quick-setting grout.For tests on individual steel H-piles or pipe piles, weld the testplate to the pile. For tes

47、ts on individual timber piles, the testplate may be set directly on the top of the pile that shall besawed off to provide full bearing of the test plate, or alterna-tively, the test plate may be set in high-strength quick-settinggrout.6.1.4 In 6.3 and 6.4, center the hydraulic jack(s) on the testpla

48、te(s) with a steel-bearing plate of adequate thickness be-tween the top(s) of the jack ram(s) and the bottom(s) of the testbeam(s). If a load cell(s) or equivalent device(s) is to be used,center it on the bearing plate above the ram(s) with anothersteel bearing plate of sufficient thickness between

49、the loadcell(s) or equivalent device(s) and the bottom(s) of the testbeam(s). Bearing plates shall be of sufficient size to accom-modate the jack ram(s) and the load cell(s) or equivalentdevice(s) and properly bear against the bottom(s) of the testbeam(s).6.1.5 In 6.5, a test plate may be used in accordance with theappropriate provisions of 6.1 or, alternatively, the test beam(s)may be set directly on the pile cap or the loading materialapplied directly on the cap. Test beam(s) set directly on the capshall obtain full bearing using high-strength quic