1、Designation: D5220 14Standard 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 D5220; 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 () 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 therm
3、alization 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.1.1.1 For limitations see Section 6 on Interferences.1.2 The water mass per unit volume, expressed as mass perunit volume of the mate
4、rial 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 of a material fo
5、r purchasingpurposes unless correlated to other accepted ASTM methods.1.4 UnitsThe values expressed in SI units are regarded asthe standard. The inch-pound units given in parentheses maybe approximate and are provided for information only.1.5 All observed and calculated values shall conform to thegu
6、ide for significant digits and rounding established in PracticeD6026.1.5.1 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 generally be reta
7、ined. 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 considerations. It i
8、s 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 appro-priate sa
9、fety 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:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD1452 Practice for Soil Exploration and Sampling by AugerBo
10、ringsD1586 Test Method for Penetration Test (SPT) and Split-Barrel Sampling of SoilsD1587 Practice for Thin-Walled Tube Sampling of Soils forGeotechnical PurposesD2113 Practice for Rock Core Drilling and Sampling ofRock for Site InvestigationD2216 Test Methods for Laboratory Determination of Water(M
11、oisture) Content of Soil and Rock by MassD2937 Test Method for Density of Soil in Place by theDrive-Cylinder MethodD3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Sampling of SoilsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock
12、asUsed in Engineering Design and ConstructionD4428/D4428M Test Methods for Crosshole Seismic Test-ingD5195 Test Method for Density of Soil and Rock In-Place atDepths Below Surface by Nuclear MethodsD6026 Practice for Using Significant Digits in GeotechnicalDataD6938 Test Method for In-Place Density
13、and Water Contentof Soil and Soil-Aggregate by Nuclear Methods (ShallowDepth)3. Terminology3.1 DefinitionsFor definitions of common technical termsin this standard, refer to Terminology D653.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibi
14、lity of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved June 15, 2014. Published June 2014. Originallyapproved in 1992. Last previous edition approved in 2008 as D5220 08. DOI:10.1520/D5220-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org,
15、 orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
16、 West Conshohocken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 detectora device to observe and measure radiation.3.2.2 dry densitysame as density of dry soil or rock (asdefined in Terminology D653); the mass of solid particles perthe total volume of soil or
17、 rock.3.2.3 neutron probea cylindrical device containing a fastneutron source and a thermal neutron detector.3.2.4 neutron (radiation) sourcea sealed radioactive ma-terial that emits neutron radiation as it decays.3.2.5 thermalizationthe process of “slowing down” fastneutrons by collisions with ligh
18、t-weight atoms, such as hydro-gen.3.2.6 volumetric water contentthe volume of water as apercent of the total volume of soil or rock material.3.2.7 wet densitysame as bulk density (as defined inTerminology D653); the total mass (solids plus water) per totalvolume.4. Summary of Test Method4.1 This tes
19、t method 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 surfacemeasure
20、ments in accordance with Test Method D6938.4.2 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
21、neutrons 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
22、 the hydrogen 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-pl
23、ace water 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
24、described 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 homogeneou
25、s andhydrogen present is in the form of water as defined by TestMethod D2216.NOTE 1The quality of the result produced by this standard test methodis dependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of
26、Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection, and the like. Users of thisstandard are cautioned that compliance with Practice D3740 does not initself assure reliable results. Reliable results depend on many factors;Practice D3740 provides a me
27、ans of evaluating some of those factors.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,
28、in forms other than water, as defined byTest Method D6938 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 th
29、e true 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-me
30、nt (see 10.1.2).6.3 The actual sample volume that the instrument measuresis indeterminate and varies with the apparatus and the watercontent of the material. In general, the greater the water contentof the material, the smaller the volume involved in themeasurement. For example, the sample volume is
31、 approxi-mately 0.048 m3(1.7 ft3) for a soil with a water content of 200kg/m3(12.5 lbm/ft3).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 mixtu
32、re of a radioactive material such asamericium or radium with 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
33、 by acable of sufficient design and length, that is capable of beinglowered down the cased hole to desired test depths.7.3 The apparatus shall be equipped with a referencestandard, a fixed shape of hydrogenous material used forchecking apparatus operation and to establish conditions for areproducibl
34、e reference count rate. It may also serve as aradiation shield.7.4 Apparatus PrecisionSee Annex A3 for the precisionof the apparatus.7.5 Accessories:7.5.1 Access TubingThe access tubing (casing) is requiredfor all access holes in nonlithified materials (soils and poorlyconsolidated rock) that cannot
35、 maintain constant boreholediameter with repeated measurements. If access tubing isD5220 142required 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 p
36、ossible to provide close proximity ofthe probe to the material under test. The same type of tubingshall be used in the field as is used in calibration.7.5.2 Drilling Tool(s)Hand auger or power drilling equip-ment that can be used to establish the access hole. Any drillingequipment that provides a su
37、itable clean open hole for instal-lation of access tubing and insertion of the probe shall beacceptable. The equipment used shall be capable of maintain-ing constant borehole diameter to ensure that the measurementsare performed on undisturbed soil and rock. The type ofequipment and methods of advan
38、cing the access hole should bereported.7.5.3 Dummy ProbeA cylindrical probe 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
39、 radioactive materials that maybe hazardous to the health of the users unless 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 knowledg
40、e of and compliance with RegulatoryRequirements, are a mandatory part of the 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
41、 necessary.9.3 Standardization and Reference Check:9.3.1 Nuclear density gauges 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-me
42、nt count rate to a count rate made on a reference standard.9.3.2 Standardization 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.
43、Perform the standardization with the gauge far enough awayfrom other apparatus 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
44、rates due to reflections from these masses or items.NOTE 2Separation of nuclear 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. Th
45、is separation can be reduced by theproper use of shielding. With regards to 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 refle
46、ctions from influencing thestandardization counts.9.3.3 Turn on the gauge 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 g
47、auge, one measurement at four ormore times the normal measurement period is 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
48、from the gaugemanufacturer, use the procedure in 9.3.5.9.3.5 If the value 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.0.98Nce2ln2
49、!tT1/2# N0#1.02Nce2ln2!tT1/2(1)where:T1/2= the half-life of the isotope that is used for the densityor moisture determination in the gauge. For ex-ample,241Am:Be, the isotope most commonly usedfor density determination in these gauges, T1/2is 157788 days,Nc= the standardization count acquired at the time of thelast calibration or verification,N0= the current standardization count,FIG. 1 Schematic Diagram; Water Content by Neutron DepthProbe MethodD5220 143t = the time that has elapsed between the current stan-dardization test and the date of the last calibratio
