ASTM D7949-2014 8494 Standard Test Methods for Thermal Integrity Profiling of Concrete Deep Foundations《混凝土深基础热完整性分析的标准试验方法》.pdf

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1、Designation: D7949 14Standard Test Methods forThermal Integrity Profiling of Concrete Deep Foundations1This standard is issued under the fixed designation D7949; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi

2、sion. 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 provide procedures for measuringthe temperature profile within a deep foundation elementconstructed using ca

3、st-in-place concrete, such as bored piles,drilled shafts, augered piles, diaphragm walls, barrettes, anddams, and alike. The thermal profile induced by the curingconcrete can be used to evaluate the homogeneity and integrityof the concrete mass within the deep foundation element.1.2 Two alternative

4、procedures are provided:1.2.1 Method A uses a thermal probe lowered into accessducts installed in the deep foundation element during construc-tion.1.2.2 Method B uses multiple embedded thermal sensorsattached to the reinforcing cage installed in the deep foundationelement during construction.1.3 All

5、 observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026, unless superseded by this standard.1.3.1 The procedures used to specify how data are collected/recorded and calculated in this standard are regarded as theindustry standar

6、d. In addition, they are representative of thesignificant 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 o

7、r reduce significant digits of reported data to com-mensurate with these considerations. It is beyond the scope ofthis standard to consider significant digits used in analysismethods for engineering design.1.4 This standard provides minimum requirements for ther-mal profiling of concrete deep founda

8、tion elements. Plans,specifications, and/or provisions prepared by a qualifiedengineer, and approved by the agency requiring the test, mayprovide additional requirements and procedures as needed tosatisfy the objectives of a particular test program.1.5 The text of this standard references notes and

9、footnotes,which provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.6 UnitsThe values stated in SI units are to be regardedas standard. No other units of measurement are included in thisstandard.NOTE

10、1ASTM International takes no position respecting the validityof any patent rights asserted in connection with any item mentioned in thisstandard. Users of this standard are expressly advised that determinationof the validity of any such patent rights, and the risk of infringement ofsuch rights, are

11、entirely their own responsibility.1.7 LimitationsProper installation of the access ducts orthermal sensors is advised for effective testing and interpreta-tion. If a flaw is detected, then the method does not give theexact type of flaw (for example, inclusion, bulge,honeycombing, lack of cement part

12、icles, and alike.) but ratheronly that a flaw exists. The method is limited primarily totesting the concrete during the early curing process.1.8 This standard may involve hazardous materials,operations, and equipment. This standard does not purport toaddress all of the safety concerns, if any, assoc

13、iated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluids

14、D3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6026 Practice for Using Significant Digits in GeotechnicalData3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms used in

15、thisstandard, refer to Terminology D653.1This 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 Nov. 1, 2014. Published November 2014. DOI:10.1520/D794914.2For referenced AST

16、M 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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc

17、ken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 access ducts, npreformed steel pipes or plastic pipes(for example, PVC or equivalent) placed in the concrete toallow thermal probe entry to measure temperature in theconcrete.3.2.2 access locations, nthe plan

18、view positions of eitheraccess ducts or longitudinally distributed groups of embeddedthermal sensors.3.2.3 defect, na flaw that, because of either size orlocation, may detract from the capacity or durability of thedeep foundation element.3.2.4 depth interval, nthe maximum incremental spacingalong th

19、e deep foundation element between embedded thermalsensor levels or probe measurements.3.2.5 embedded thermal sensor, na temperature measur-ing device cast in the concrete that meets the requirements of6.3.5.3.2.6 effective radius, nthe radius of intact uncompro-mised concrete that would result in th

20、e measured temperatureto account for a change in concrete quality or change insection.3.2.7 flaw, na deviation from the planned shape or mate-rial (or both) of the deep foundation element.3.2.8 measurement location, nthe position of a tempera-ture measurement as defined by depth (or elevation) and t

21、heaccess location.3.2.9 sensor level, nthe depth or elevation where anembedded thermal device is located or where a temperaturemeasurement is taken.3.2.10 thermal probe, na slender device inserted intoaccess ducts to measure temperature that meets the require-ments of 6.3.1.3.2.11 thermal profile, n

22、a temperature versus depth plotwhich can be prepared from a single access location or fromthe average temperature of all access locations versus depth.4. Summary of Test Method4.1 Exothermic chemical processes generate heat as con-crete cures within a cast-in-place deep foundation element. Theamount

23、 of heat generated and the rate of heat dissipation arestrongly influenced by the concrete mix and by the size andshape of the deep foundation element. Therefore, temperaturemeasurements within the deep foundation element provide athermal profile from which to evaluate the consistency of theconcrete

24、 and the regularity of its shape. Temperature measuredat the reinforcing cage, typically near the perimeter, will belower than the core temperature due to heat dissipation into thesurroundings (for example, soil, rock, water or air). If the cageis not concentric within the foundation element, then t

25、heportions of the cage closer to the perimeter will be coolerduring those times when elevated temperatures exist. Portionscloser to the center will be warmer. A flaw in the form of avoid, a neck, an inclusion, or poor quality concrete willgenerate less heat than the normal concrete around it, result

26、ingin lower temperature near the flaw. Conversely, a bulge willhave more effective concrete cover, resulting in higher tem-perature near the bulge. Temperature measurements at accesslocations equally spaced around the circumference of thereinforcement cage and at regular depth intervals allow the us

27、erto identify potentially weak zones of concrete, to estimate theeffective size of the foundation, and to check concrete coverand cage alignment along the length of the foundation element.4.2 Along the axis of a cast-in-place concrete deep founda-tion element and away from the ends, heat dissipates

28、primarilyin the radial direction. However, within approximately onediameter of the top and bottom of the deep foundation element,heat dissipates in both the axial and radial directions, resultingin more rapid cooling and reduced temperature.Analysis of thethermal profile near the bottom may help to

29、evaluate the lengthof the deep foundation element and its shape at the bottom.4.3 Cast-in-place piles with diameters less than 600 mm canbe assessed by a single access location adjacent to the centerreinforcing rod.NOTE 2During the initial concrete hydration period of a deepfoundation element, heat

30、production exceeds the rate of dissipation intothe surrounding material, and thus it dominates the early thermal profile.Analysis also shows that the degree of saturation in the surroundingmaterial has little effect on the early thermal profile. Interpretation of thethermal profile should consider a

31、ny significant changes in the thermaldiffusivity of the environment around the deep foundation element, forexample, when it extends above the ground surface through air or water.NOTE 3The quality of the result produced by this standard isdependent on the competence of the personnel performing it, an

32、d thesuitability of the equipment and facilities used. 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 assurereliabl

33、e results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.5. Significance and Use5.1 Temperature measurements taken from a thermal probelowered into access ducts in the deep foundation element, orfrom embedded thermal sensors distributed a

34、long the length,can be used to assess the homogeneity and integrity of concreteboth inside and outside the reinforcing cage, as well asplacement of the cage relative to the center of the curingconcrete.3,4NOTE 4If flaws are detected, then further evaluation and potentialremediation may be warranted

35、to determine if the flaw is a defect. Anyinterpretation is qualitative and possibly relative to the particular deepfoundation element material, construction characteristics of the testedstructure, and the apparatus used. Interpretation therefore should containproper engineering judgment and experien

36、ce.6. Apparatus6.1 Method A: Apparatus for Internal Inspection (AccessDucts)To provide access for the thermal probe, access ductsmade from pipe or round tube shall be installed duringconstruction of the deep foundation element.Access ducts shallhave a nominal inside diameter of 38 to 50 mm (38 mm is

37、3Mullins, G., “Thermal Integrity Profiler of Drilled Shafts,” DFI Journal Vol 4.No. 2 December 2010: Deep Foundations Institute, Hawthorne, NJ, December,2010, pp. 54-64.4Mullins, G. and Kranc, S., “Thermal integrity testing of drilled shafts,” FinalReport, FDOT Project BD544-20, University of South

38、Florida, May 2007.D7949 142preferred to reduce cage congestion) and shall be straight,rigid, and strong enough to withstand crushing from fluidconcrete pressure. Ducts shall have a regular internal diameter,be free of obstructions, including duct joints, and shall permitthe unobstructed passage of t

39、he probe. Ducts shall be water-tight. Ducts may be extended using external mechanicalcouplings.6.2 Apparatus for Determining Physical Test Parameters:6.2.1 Weighted Measuring TapeA weighted measuringtape shall be used as a dummy probe to check free passagethrough and determine the unobstructed lengt

40、h of each accessduct to the nearest 50 mm. The weight shall have a diameterequal to or greater than the probe and less than the insidediameter of the access duct.6.2.2 Magnetic CompassA magnetic compass accurate towithin 10 shall be used to document the access locationdesignations compared with the

41、site layout plan. Alternately,access locations shall be labeled based on the site plan,structure orientation or other methods to document accesslocation designations assigned and used for reporting testresults.6.3 Apparatus for Obtaining Measurements:6.3.1 Method A: Thermal ProbeThe thermal probe sh

42、allbe equipped with a sufficient number of sensors (minimumtwo, oriented diagonally opposite) to obtain the averagetemperature around the perimeter of the access duct wall towithin 1C accuracy.6.3.2 Method A: Signal Transmission CableThe signalcable used to deploy the probe and transmit data from th

43、e probeshall be robust to support the probe weight. The cable shall beabrasion resistant to allow repeated field use and maintainflexibility in the range of anticipated temperatures.6.3.3 Method A: Probe Depth-Measuring DeviceThe lo-cation of the probe in the access duct shall be tracked with adepth

44、 encoding device throughout the test; for example byengaging the signal cables over a pulley equipped with adepth-encoding device. The design of the depth-measuringdevice shall be such that cable slippage shall not occur. Thedepth-measuring device shall be accurate to within1%oftheaccess duct length

45、, or 0.15 m, whichever is larger. The depthsensors shall have a readability to the nearest 0.1 m.6.3.4 Method A: ContainerAcontainer of sufficient size tohold the expected amount of water from the access tubes (forexample, something like a bucket).6.3.5 Method B: Embedded Thermal SensorsWhen usingMe

46、thod B, embedded thermal sensors shall be installed atprescribed access locations defined by 3.2.2 and further speci-fied by 7.3.1 where the sensor levels at one access locationcorrespond to the same depth (or elevation) of the other accesslocations. The sensors may be installed individually or con-

47、nected together in an array of sensors that may be individuallypolled to measure the temperature at each sensor. The thermalsensors shall have an accuracy of 1C. The thermal sensorsshall have a readability to the nearest 0.1C. The wire(s)connected to the sensors shall be abrasion resistant and remai

48、noperational in the range of anticipated temperatures.6.4 Apparatus for Recording, Processing and DisplayingData:6.4.1 Recording ApparatusThe recording apparatus shallrecord depth and temperature data from each access duct orgroup of embedded thermal sensors at a depth interval nogreater than 500 mm

49、. Typical schematic arrangements for thetest apparatus are illustrated in Figs. 1 and 2. For MethodA, theapparatus shall read the depth-measuring device and assign adepth to each probe temperature reading. The apparatus shallstore the temperature data versus depth from each accesslocation (access duct or group of embedded thermal sensors).For either Procedure, all stored data (temperature versus depth)shall have identifying header information attached to it describ-ing the test location, measurement location identifier, time/datestamp, and all pertinent