1、Designation: D 5220 08Standard Test Method forWater Mass per Unit Volume of Soil and Rock In-Place bythe Neutron Depth Probe Method1This standard is issued under the fixed designation D 5220; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the calculation of the watermass per unit volume of soil and rock by the
3、rmalization orslowing of fast neutrons where the neutron source and thethermal neutron detector are placed at the desired depth in thebored hole lined by an access tube (see Note 3).1.1.1 For limitations see Section 6 on Interferences.1.2 The water mass per unit volume, expressed as mass perunit vol
4、ume of the material under test, is calculated bycomparing the thermal neutron count rate with previouslyestablished calibration data (see Annex A1).1.3 A precision statement has not been developed for thisstandard at this time. Therefore, this standard should not beused for acceptance or rejection o
5、f a material for purchasingpurposes unless correlated to other accepted ASTM methods.1.4 The values expressed in SI units are regarded as thestandard. The inch-pound units given in parentheses may beapproximate and are provided for information only.1.5 All observed and calculated values shall confor
6、m to theguide for significant digits and rounding established in PracticeD 6026.1.5.1 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 thesignificant digits that should genera
7、lly 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 becommensurate with these considera
8、tions. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.6 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 appr
9、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific hazards aregiven in Section 8.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 1452 Practice for Soil Investigation and Samp
10、ling byAuger BoringsD 1586 Test Method for Penetration Test (SPT) and Split-Barrel Sampling of SoilsD 1587 Practice for Thin-Walled Tube Sampling of Soilsfor Geotechnical PurposesD2113 Practice for Rock Core Drilling and Sampling ofRock for Site InvestigationD 2216 Test Methods for Laboratory Determ
11、ination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2937 Test Method for Density of Soil in Place by theDrive-Cylinder MethodD 3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Sampling of SoilsD 3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspe
12、ction of Soil and Rock asUsed in Engineering Design and ConstructionD 4428/D 4428M Test Methods for Crosshole Seismic Test-ingD 5195 Test Method for Density of Soil and Rock In-Placeat Depths Below Surface by Nuclear MethodsD 6026 Practice for Using Significant Digits in Geotechni-cal DataD 6938 Tes
13、t Method for In-Place Density and Water Con-tent of Soil and Soil-Aggregate by Nuclear Methods(Shallow Depth)1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current editi
14、on approved Oct. 1, 2008. Published October 2008. Originallyapproved in 1992. Last previous edition approved in 2002 as D 5220 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informat
15、ion, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 See Terminology D 653 for genera
16、l definitions.3.2 Definitions of Terms Specific to This Standard:3.2.1 detectora device to detect and measure radiation.3.2.2 dry densitysame as density of dry soil or rock (asdefined in Terminology D 653); the mass of solid particles perthe total volume of soil or rock.3.2.3 neutron probea cylindri
17、cal device containing a fastneutron source and a thermal neutron detector.3.2.4 neutron (radiation) sourcea sealed source of radio-active material that emits neutron radiation as it decays.3.2.5 thermalizationthe process of “slowing down” fastneutrons by collisions with light-weight atoms, such as h
18、ydro-gen.3.2.6 volumetric water contentthe volume of water as apercent of the total volume of soil or rock material.3.2.7 water contentthe ratio of the mass of water con-tained in the pore spaces of soil or soil-aggregate, to the solidmass of particles in that material, expressed as a percentage(thi
19、s is sometimes referred to in some scientific fields asgravimetric water content to differentiate it from volumetricwater content).3.2.8 wet densitysame as bulk density (as defined inTerminology D 653); the total mass (solids plus water) per totalvolume.4. Summary of Test Method4.1 This test method
20、uses thermalization of neutron radia-tion to calculate the in-place water mass per unit volume of soiland rock at various depths by placing a probe containing aneutron source and a thermal neutron detector at desired depthsin a bored hole lined by an access tube as opposed to surfacemeasurements in
21、accordance with Test Method D 6938.4.2 Neutrons emitted by the source are thermalized (slowed)by collisions with materials of low atomic numbers. Hydrog-enous materials, such as water and other compounds contain-ing hydrogen, are most effective in thermalizing neutrons. Inthis apparatus the neutrons
22、 thermalized by the material undertest are detected by the thermal neutron detector.4.3 In the absence of interference elements as discussed inSection 6, the number of thermalized neutrons is a function ofthe hydrogen content of the material under test and the watercontent is proportional to the hyd
23、rogen content.4.4 By the use of a calibration process the water mass perunit volume is calculated by correlating the count rate toknown water mass per unit volume values.5. Significance and Use5.1 This test method is useful as a rapid, nondestructivetechnique for the calculation of the in-place wate
24、r mass per unitvolume of soil and rock at desired depths below the surface.5.2 This test method is useful for informational and researchpurposes. It should only be used for quality control andacceptance testing when correlated to actual water mass perunit volume using procedures and methods describe
25、d inA1.2.3.5.3 The non-destructive nature of this test method allowsrepetitive measurements to be made at a single test location forstatistical analysis and to monitor changes over time.5.4 The fundamental assumptions inherent in this testmethod are that the material under test is homogeneous andhyd
26、rogen present is in the form of water as defined by TestMethod D 2216.NOTE 1The quality of the result produced by this standard testmethod is dependent on the competence of the personnel performing it,and the suitability of the equipment and facilities used.Agencies that meetthe criteria of Practice
27、 D 3740 are generally considered capable ofcompetent and objective testing/sampling/inspection, and the like. Usersof this standard are cautioned that compliance with Practice D 3740 doesnot in itself assure reliable results. Reliable results depend on manyfactors; Practice D 3740 provides a means o
28、f evaluating some of thosefactors.6. Interferences6.1 The sample heterogeneity, density, and chemical com-position of the material under test will affect the measurements.The apparatus must be calibrated to the material under test oradjustments made in accordance with Annex A2.6.1.1 Hydrogen, in for
29、ms other than water, as defined byTest Method D 2216 and carbon, present in organic soils, willcause measurements in excess of the true water value. Someelements such as boron, chlorine, and minute quantities ofcadmium, if present in the material under test, will causemeasurements lower than the tru
30、e water value.6.2 This test method exhibits spatial bias in that it is moresensitive to water contained in the material closest to the accesstube. The measurement is not necessarily an average watercontent of the total sample involved.6.2.1 Voids around the access tube can affect the measure-ment (s
31、ee 10.1.2).6.3 The sample volume is approximately 0.048 m3(1.7 ft3)with a water content of 200 kg/m3(12.5 lbm/ft3). The actualsample volume is indeterminate and varies with the apparatusand the water content of the material. In general, the greater thewater content of the material, the smaller the v
32、olume involvedin the measurement.7. Apparatus (See Fig. 1)7.1 The apparatus shall consist of a nuclear instrumentcapable of measuring water mass per unit volume at variousdepths below the surface containing the following:7.1.1 A sealed mixture of a radioactive material such asamericium or radium wit
33、h a target element such as beryllium,and a suitable thermal neutron detector, and7.1.2 A suitable timed scaler and power source.7.2 The apparatus shall be equipped with a cylindrical probecontaining the neutron source and detector, connected by acable of sufficient design and length, that is capable
34、 of beinglowered down the cased hole to desired test depths.7.3 The apparatus shall be equipped with a reference stan-dard, a fixed shape of hydrogenous material used for checkingapparatus operation and to establish conditions for a reproduc-ible reference count rate. It may also serve as a radiatio
35、n shield.7.4 Apparatus PrecisionSee Annex A3 for the precisionof the apparatus.7.5 Accessories:D52200827.5.1 Access TubingThe access tubing (casing) is requiredfor all access holes in nonlithified materials (soils and poorlyconsolidated rock) that cannot maintain constant boreholediameter with repea
36、ted measurements. If access tubing isrequired the tubing shall be of a material such as aluminum,steel, or polyvinyl chloride, having an interior diameter largeenough to permit probe access without binding. The tubingshall be as thin-walled as possible to provide close proximity ofthe probe to the m
37、aterial under test. The same type of tubingshall be used in the field as is used in calibration.7.5.2 Hand auger or power drilling equipment that can beused to establish the access hole. Any drilling equipment thatprovides a suitable clean open hole for installation of accesstubing and insertion of
38、the probe shall be acceptable. Theequipment used shall be capable of maintaining constantborehole diameter to ensure that the measurements are per-formed on undisturbed soil and rock. The type of equipmentand methods of advancing the access hole should be reported.7.5.3 Dummy ProbeA cylindrical prob
39、e the same size asthe probe containing the neutron source and a chain or cable ofsufficient design and length to permit lowering the dummyprobe down the cased hole to desired test depths.8. Hazards8.1 These instruments utilize radioactive materials that maybe hazardous to the health of the users unl
40、ess proper precau-tions are taken. Users of these instruments must becomefamiliar with applicable safety procedures and governmentregulations.8.2 Effective user instructions, together with routine safetyprocedures and knowledge of and compliance with RegulatoryRequirements, are a mandatory part of t
41、he operation andstorage of these instruments.9. Calibration, Standardization, and Reference Check9.1 Calibrate the instrument in accordance with Annex A1.9.2 Adjust the calibration in accordance with Annex A2 ifadjustments are necessary.9.3 Standardization and Reference Check:9.3.1 Nuclear density g
42、auges are subject to long-term agingof the radioactive sources, which may change the relationshipbetween count rates and the material density. To correct for thisaging effect, gauges are calibrated as a ratio of the measure-ment count rate to a count rate made on a reference standard.9.3.2 Standardi
43、zation of the gauge shall be performed at thestart of each days use, and a record of these data should beretained for the amount of time required to ensure compliancewith either Section 9.3.4 or 9.3.5, whichever is applicable.Perform the standardization with the gauge far enough awayfrom other appar
44、atus containing radioactive sources to preventinterference due to radiation from the other apparatus. Inaddition, perform the standardization far enough away fromlarge masses or other items which can affect the referencecount rates due to reflections from these masses or items.NOTE 2Separation of nu
45、clear gauges by a distance of 9 m (30 ft) fromone another has typically proven sufficient in preventing radiation fromone gauge from being detected by another gauge and potentially causingan incorrect standardization count. This separation can be reduced by theproper use of shielding. With regards t
46、o reflections from large masses orother items potentially causing incorrect standardization counts, a sepa-ration of1m(3ft)between the gauge and the mass or item in question hastypically proven sufficient to prevent such reflections from influencing thestandardization counts.9.3.3 Turn on the gauge
47、and allow for stabilization accord-ing to the manufacturers recommendations.9.3.4 Using the reference standard, take at least four repeti-tive readings at the normal measurement period and obtain themean. If available on the gauge, one measurement at four ormore times the normal measurement period i
48、s acceptable. Thisconstitutes one standardization check. Use the procedure rec-ommended by the gauge manufacturer to establish the compli-ance of the standard measurement to the accepted range.Without specific recommendations from the gauge manufac-turer, use the procedure in 9.3.5.9.3.5 If the valu
49、e of the current standardization count isoutside the limits set by Eq 1, repeat the standardization check.If the second standardization check satisfies Eq 1, the gauge isconsidered in satisfactory operating condition.0.99Nc!eln2!tT1/2 #N0#1.01Nc!eln2!tT1/2 (1)where:T1/2= the half-life of the isotope that is used for thedensity or moisture determination in the gauge. Forexample,241Am:Be, the isotope most commonlyused for density determination in these gauges, T1/2is 157 788 days,FIG. 1 Schematic Diagram; Water Content by Neutron DepthProbe MethodD5220083Nc= the
