ASTM E2583-2007 Standard Test Method for Measuring Deflections with a Light Weight Deflectometer (LWD)《用轻型偏度计(LWD)测量偏斜的标准试验方法》.pdf

1、Designation: E 2583 07Standard Test Method forMeasuring Deflections with a Light Weight Deflectometer(LWD)1This standard is issued under the fixed designation E 2583; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last

2、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of deflectionsof paved and unpaved surfaces with a Light Weight Deflecto-meter

3、(LWD). This device is also referred to as a PortableFalling-Weight Deflectometer (PFWD). The LWD is light-weight, portable and generally used for testing unboundpavement layers. The deflections measured using an LWD canbe used to determine the stiffness of bound and unboundpavement surfaces using ap

4、propriate back- or forwardcalcula-tion analysis techniques.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is ther

5、esponsibility 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.2. Referenced Documents2.1 ASTM Standards:2D 2487 Practice for Classification of Soils for EngineeringPurposes (Unified Soil Classi

6、fication System)D 4695 Guide for General Pavement Deflection Measure-ments2.2 Other Standards:3FHWA-HRT-06-132 Version 4.1 Long-Term Pavement Per-formance Program Manual for Falling Weight Deflecto-meter Measurements3. Summary of Test Method3.1 This test method is a type of plate-bearing test. The l

7、oadis a force pulse generated by a falling weight (mass) droppedon a buffer system that transmits the load pulse through a plateresting on the material to be tested. The test apparatus may behand held or moved around with a dolly type device.3.2 The weight is raised to the height that, when dropped,

8、will impart the desired force pulse. The weight is dropped andthe resulting vertical movement or deflection of the surface ismeasured using suitable instrumentation. Multiple tests at thesame drop height (different heights are optional) may beperformed at the same location.3.3 The peak deflection re

9、sulting from the force pulse ateach location is recorded in micrometres, millimetres, mils orinches, as appropriate.3.4 The peak force imparted by the falling weight isrecorded as the force in kN or lbf, or as the mean stress (theforce divided by the load plate area) in kN/m2(kPa) or psi, asappropri

10、ate.4. Significance and Use4.1 This test method covers the determination of surfacedeflections as a result of the application of an impulse load. Theresulting deflections are measured at the center of the appliedload and may also be measured at various distances away fromthe load. Deflections may be

11、 either correlated directly topavement performance or used to determine in-situ materialcharacteristics of the pavement layers. Some uses of datainclude quality control and quality assurance of compactedlayers, structural evaluation of load carrying capacity, anddetermination of thickness requiremen

12、ts for highway andairfield pavements (see Guide D 4695).NOTE 1Since pavement and subgrade materials may be stress depen-dent, care must be taken when analyzing LWD test data on unboundmaterials so that the applied stress will closely match the stress valueapplied by the design wheel load at the pave

13、ment surface.NOTE 2The volume of the pavement and subgrade materials affectedby the load is a function of the magnitude of the load. Therefore, care mustbe taken when analyzing the results, since the data obtained by the LWDmay be obtained from a smaller volume of the unbound materials thanunder the

14、 influence of a heavy moving wheel load at the pavement surface.5. Apparatus5.1 Instrument System, conforming to the following generalrequirements:1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.41 on

15、Pavement Testing, Evaluation, and Management Methods.Current edition approved Sept. 1, 2007. Published October 2007.2For 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

16、the standards Document Summary page onthe ASTM website.3Available from the Federal Highway Administration (FHWA), 1200 NewJersey Ave., SE Washington, DC 20590.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Instruments Exposed to

17、 the Elements, shall be operablein the temperature range of -10 to 50C (10 to 120F) and shalltolerate relatively high humidity, rain or spray, and all otheradverse conditions such as dust, shock, or vibrations that maynormally be encountered.5.3 Force-Generating Device, (a falling weight) with aguid

18、e system. The force-generating device shall be capable ofbeing raised to a predetermined height and dropped. Theresulting force pulse transmitted to the pavement shall becapable of providing a half-sine or haversine shaped loadpulse, with a time of loading of between 20 and 40 msecs, andshall be rep

19、roducible within the requirements of 7.1.5.4 Falling Weight, designed to operate with negligiblefriction or resistance.5.5 Load Plate, capable of an approximately uniform dis-tribution of the impulse load on the surface. The instrumentshall be suitably constructed to allow pavement deflectionmeasure

20、ments at the center of the point of impact, through ahole in the center of the load plate.5.6 Deflection Sensor(s), capable of measuring the maxi-mum vertical movement and mounted in such a manner as tominimize angular rotation with respect to its measuring planeat the maximum expected movement. The

21、 number and spacingof the sensors is optional and will depend upon the purpose ofthe test and the pavement layer characteristics. Sensors may beof several types such as displacement transducers, velocitytransducers, or accelerometers.5.7 Data Processing and Storage System. Load and deflec-tion data

22、shall be displayed and recorded. Supporting informa-tion such as air temperature, surface temperature, distancemeasurements, and identification data for each test point maybe recorded either automatically or manually.5.8 Load Cell. A load cell shall be used to measure theapplied load of each impact.

23、 It shall be placed in a position tominimize the mass between the load cell and the surface. Theload cell shall be positioned in such a way that it does notrestrict the ability to obtain deflection measurements under thecenter of the load plate. The load cell shall be water resistantand shall be res

24、istant to mechanical shocks from impactsduring testing or traveling.5.9 LWD Size, shall be small enough to be consideredportable, i.e. not requiring a vehicle or trailer for transport.6. Hazards6.1 Injury can occur when elevating and dropping thefalling weight. Some LWDs have relatively heavy fallin

25、gweights, thus requiring the operator/recorder to keep his/herback straight, lifting with the leg muscles. Likewise, theoperator/recorder should take care that his/her hands or ex-tremities are not positioned beneath the lifted weight or loadingplate, to avoid injury when the weight is falling.7. Ca

26、libration7.1 Force-Generating DevicePrior to load and deflectionsensor calibration, precondition the device by dropping theweight at least five times and checking the relative differencein each peak load level. Peak load levels measured by the loadcell shall not vary from each other more than 63%.If

27、thevariation exceeds this tolerance, the height of the drop,cleanliness of the track, along with any springs or rubber padsthat are used to condition the load, shall be checked. Improp-erly operating parts shall be replaced or repaired prior tocalibration to ensure that the horizontal and shear forc

28、es areminimized.7.2 Load Calibration PlatformFollow the manufacturersrecommendations for load cell calibration since several typesof these devices are commercially available.7.3 Deflection SensorsCalibrate sensors at least once peryear or in accordance with the manufacturers recommenda-tions.8. Sign

29、al Conditioning and Recorder System8.1 All signal conditioning and recording equipment shallallow deflection measurements to be displayed and stored witha resolution of 61m(60.04 mils) or less.8.2 The peak load and deflection measurements shall berecorded within a time period or measurement window o

30、f 60ms or longer while still adhering to the precision and biasrequirements shown in Section 10.8.3 Peak load measurements shall be displayed and storedwith a resolution of 60.1 kN or less if using SI units, or 610lbf or less if using U.S. customary units, or an equivalentquantity if the load is exp

31、ressed as mean stress depending onthe plate radius.9. Procedure9.1 Position the instrument over the desired test point. Thetest surface shall be as clean and smooth as possible with loosegranules and protruding material removed. For gravel surfacesit is recommended that a thin layer of fine sand be

32、placed overthe test point. This helps in obtaining uniform contact betweenthe load plate and the surface. A suitable rubber pad may beused for improving the load distribution.9.2 Place the loading plate and the sensors to ensure they areresting on a firm and stable test surface.9.3 Raise the falling

33、 weight to the desired height and allowit to fall freely.9.4 Record the resulting peak surface deflection(s) and thepeak load.9.5 Perform at least two falling weight sequences (9.3) andcompare the results. If the difference is greater than 63 % forany sensor, note the variability in the report. Addi

34、tional testsmay be run at the same or at different load levels.NOTE 3It may be advantageous to use the first one or two drops forseating and use the subsequent drops for analysis.10. Precision and Bias10.1 Equipment PrecisionThe precision requirement forthe deflection sensors is 62 m (0.08 mils). Th

35、e precisionrequirement for the load cell is 60.1 kN (22 lbf) or better10.2 Equipment BiasThe bias requirement for both thedeflection sensors and the load cell is 62 % or better.10.3 Between Device and Test Point ReproducibilityThesingle operator, single equipment coefficient of variation of thetest

36、method for typical field conditions is 10 to 20 percent forGM/GC/GP soils, 15 to 35 percent for SW/SM/SP soils, and 40to 60 percent for ML/CL soils (see Practice D 2487). Thebetween device reproducibility of the test method for typicalE2583072conditions is being determined and will be available on o

37、rbefore December 2009.NOTE 4Some LWD devices are designed and equipped such that theaccuracy (precision and bias) as well as the load cell and sensor mountingrequirements of this test method cannot be met. One or more of thefollowing LWD features can lead to this conclusion: (1) The LWD is notequipp

38、ed with a load measuring device (load cell); (2) The LWD measuresthe deflection of the load plate rather than the deflection of the surfaceunder test through a hole in the center of the load plate; (3) The LWD usesa sensor (velocity transducer or accelerometer) that is not linear down tozero Hz or i

39、s not processed using a Fourier transform analysis orequivalent.NOTE 5For the LWD devices referred to in Note 4, the approximatesurface or composite modulus of the tested layer has been estimated to liebetween 0.5 and 0.75 times the composite modulus calculated using anLWD device that meets the prec

40、ision and bias requirements of this testmethod. A separate test method is being developed to cover this type ofLWD device.11. Keywords11.1 deflection surveys; deflection testing; Falling WeightDeflectometer (FWD); Light Weight Deflectometer (LWD);impulse deflection testing; load-deflection testing;

41、Nondestruc-tive testing (NDT); pavement deflection; pavement testing;pavement layer modulus; pavement layer stiffness; PortableFalling-Weight Deflectometer (PFWD)ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this st

42、andard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be rev

43、iewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsi

44、ble technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E2583073