1、Designation: D 6539 00 (Reapproved 2006)e1Standard Test Method forMeasurement of Pneumatic Permeability of PartiallySaturated Porous Materials by Flowing Air1This standard is issued under the fixed designation D 6539; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, 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.e1NOTEMercury warning editorially added in March 2008.1. Scope1.1 This test method
3、 covers laboratory determination of thecoefficient of permeability for the flow of air (pneumaticpermeability) through partially saturated porous materials.1.2 This test method may be used with undisturbed orcompacted coarse grained soils, silts, or lean cohesive soils thathave a low degree of satur
4、ation and that have pneumaticpermeability between 0.001 square micrometre (1.01 milli-darcy) and 100 square micrometre (101 darcy).1.3 The values stated in SI units are to be regarded as thestandard, unless other units are specifically given. By traditionin U.S. practice, the pneumatic permeability
5、of porous media isreported in units of darcy, although the SI unit for pneumaticpermeability is square metre.1.4 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 safety
6、 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft
7、-lbf/ft3(600kN-m/m3)D 854 Test Methods for Specific Gravity of Soil Solids byWater PycnometerD 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 1557 Test Methods for Laboratory Compaction Charac-teristics of Soil Using Modi
8、fied Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Sampling of SoilsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testi
9、ng and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4220 Practices for Preserving and Transporting SoilSamplesD 4525 Test Method for Permeability of Rocks by FlowingAirD 4564 Test Method for Density and Unit Weight of Soil inPlace by the Sleeve MethodD 4753 Guide for
10、 Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 4767 Test Method for Consolidated Undrained TriaxialCompression Test for Cohesive SoilsD 5084 Test Methods for Measurement of Hydraulic Con-ductivity of Saturated Porous Mater
11、ials Using a FlexibleWall PermeameterD 5856 Test Method for Measurement of Hydraulic Con-ductivity of Porous Material Using a Rigid-Wall,Compaction-Mold PermeameterE1 Specification for ASTM Liquid-in-Glass ThermometersE 145 Specification for Gravity-Convection and Forced-Ventilation Ovens1This test
12、method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.04 on HydrologicProperties and Hydraulic Barriers.Current edition approved Feb. 1, 2006. Published March 2006. Originallyapproved in 2000. Last previous edition approved in 2000
13、 as D 653900.2For 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 the standards Document Summary page onthe ASTM website.TABLE 1 Viscosity of Air, , as a Function of Tem
14、peratureTemperature, C Viscosity, Pas12 1.778 3 10514 1.788 3 10516 1.798 3 10518 1.808 3 10520 1.818 3 10522 1.828 3 10524 1.837 3 10526 1.847 3 10528 1.857 3 1051Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 Defi
15、nitions of Terms Specific to This Standard:3.1.1 darcya porous medium has a permeability of onedarcy when a single-phase fluid of 1-MPas (1-cP) viscositythat completely fills the voids of the medium will flow throughit under conditions of laminar (viscous) flow at a rate of 1cm3/s/cm2of cross-sectio
16、nal area under a pressure gradient of1.013 3 105Pa (1 atm)/cm. (One darcy = 0.9869 square micrometre.)3.1.2 effective confining stress, (Flexible Wall Methodonly)the difference between the permeameter cell confiningpressure and the mean specimen pore-air-water pressures.3.1.2.1 The effective confini
17、ng stress is assumed to bedistributed as a radial vector exhibiting a linear gradient alongthe length of the specimen with a minimum at the inlet and amaximum at the outlet.3.1.2.2 For the purposes of this test method, the effectiveconfining stress is stated as a scalar value and calculated as theco
18、nfining gage pressure minus the average of the specimeninlet and outlet gage pressures.3.1.3 gage pressurepressure measured relative to ambientatmospheric pressure.3.1.4 pneumatic permeabilitythe capacity of a porousmedium to conduct gas in the presence of a gas (air) pressuregradient measured as th
19、e ratio of volumetric flow through aspecimen to the resultant pressure drop across it. Also com-monly known as pneumatic conductivity or permeability to air.3.2 For definitions of other terms used in this test method,see Terminology D 653.4. Significance and Use4.1 This test method applies to the on
20、e-dimensional laminar(viscous) flow of air in porous materials such as soil.NOTE 1This test method deals with porous materials with bothgaseous (air) and liquid (pore water) mobile fluids: The liquid phase ismuch less compressible, has a higher viscosity, and is much more tightlybound to the solid p
21、hase by chemical forces. The assumption of single-phase flow may still be presumed to be valid since the test gradientensuring the conditions of laminar flow may be low enough that flow ofthe liquid phase is negligible.4.2 The degree of saturation of the specimen shall be lessthan that which would p
22、roduce significant internal transport ofpore water or alter the continuity of air voids under the appliedpneumatic gradients. The maximum permissible degree ofsaturation must be evaluated by an experienced analyst. In noinstance shall the specimen be so saturated that pore waterappears at the exit o
23、f the permeameter cell during the test.4.3 This test method is based on the assumption that the rateof mass flow through the specimen is constant with time.NOTE 2When a specimen contains volatile materials this assumptionis violated. The mass of gas flowing out will be greater than that flowingin, t
24、he pneumatic gradient is indeterminate and the test may becomemeaningless. Such specimens pose special problems and must be decon-taminated before analysis in order to minimize health and safety concernsand to prevent contamination of the test apparatus.4.4 The pneumatic permeability of porous mater
25、ials may bestrongly dependent on a variety of physical properties includ-ing the void ratio, the degree of saturation, percent anddirection of compaction, and so forth. It is beyond the scope ofthis test method to elaborate these dependencies. Rather, thistest method is intended to be a measurement
26、technique fordetermining the pneumatic permeability under a certain set oflaboratory conditions. It is the responsibility of the requestor tospecify which soil parameters must be controlled to ensure avalid extension of the test results to field conditions.4.5 It is assumed that Darcys Law is valid.
27、 The validity ofDarcys law may be evaluated by plotting the volumetric flowthrough the specimen against the differential pressure dropacross the specimen. If the individual test points lie within25 % of a straight line passing through the origin, then Darcyslaw may be taken as valid.NOTE 3Darcys law
28、 is valid only when saturation does not changeover time. Long measurement times associated with the use of bubblemeters and manometers may indirectly be an uncontrolled source ofvariability when plotting flow versus pressure drop (see 8.2). Therecommended use of digital electronic flow and pressure
29、sensors leads toconsiderably reduced measurement times because the user can quicklydetermine by inspection when a steady state condition has been reached.At that point only a single reading needs to be taken for a reliablemeasurement. A rapid course of measurement will minimize dehydrationof partial
30、ly saturated specimens.NOTE 4Humidifying the test gas to minimize specimen dehydration isnot recommended because: (1) there is no practical way to either measureor control the relative humidity of the test gas, either at the inlet or outletof the specimen; (2) the calibration of the electronic flowm
31、eter is for dryair only and would become unreliable in the presence of water vapor,especially in view of the potential for irreversible adsorption of moistureon the sensor elements; (3) there is a danger of permanent watercondensation in the static transfer lines and other apparatus dead volumes;and
32、 (4) the test apparatus would become more complex and difficult touse.4.6 This test method covers the use of two different types ofpermeameter cells, flexible wall and rigid wall, and two typesof air flow regulation, mass flow control and pressure control.4.7 A flexible wall permeameter is the prefe
33、rred means forconfining the test specimen in accordance with Test MethodsD 5084, D 4525, and D 4767. This test method may beperformed using a rigid wall permeameter and all reference toeffective confining stress and the permeameter cell pressuresystem shall be disregarded.4.8 For some specimens, the
34、 pneumatic permeability will bestrongly dependent on the effective confining stress due toporosity reduction. Whenever possible, the requestor shouldspecify the field overburden conditions at which this testmethod is to be performed. In some specimens, this stress willvary significantly with flow in
35、 an indeterminate way. Allspecimens should be evaluated for this effect by performingthis test method at two or more different confining stress valueswhen a flexible wall permeameter is used.4.9 This test method is intended to support soil remediationoperations such as: soil vapor extraction, air sp
36、arging, back-filling of soils in utility trenches, and similar engineeringactivities.4.10 The correlation between results obtained with this testmethod and in situ field measurements has only been partiallyestablished. The small laboratory specimen used in this methodmay not be representative of the
37、 distributed condition on-sitedue to vadose zone fluctuations, changes in soil stratigraphy,D 6539 00 (2006)e12and so forth. For this reason, laboratory test results should beapplied to field situations with caution by qualified personnel.NOTE 5This test method is dependent on the competence of thep
38、ersonnel performing it and the suitability of the equipment and facilitiesused. Agencies which meet the criterion of Practice D 3740 are generallyconsidered capable of competent and objective testing.5. Apparatus5.1 Pneumatic PermeameterThe pneumatic permeametershall be capable of rapidly establishi
39、ng a constant flow of airthrough the test specimen and measuring the consequentpressure drop across it. A schematic diagram is shown in Fig.1.5.1.1 Air SupplyThe compressed air supplied to the pneu-matic system shall:5.1.1.1 Be pulsation-free, have sufficient volumetric capac-ity at all anticipated
40、flow rates, be free of water vapor to a dewpoint of 70C (94F) or less, and be free of oil,5.1.1.2 Be free of particulate matter greater than 5 m indiameter, and5.1.1.3 Be provided with a monitoring gage and regulator todeliver a pressure of at least 350 6 5 kPa (50 6 1 psi).NOTE 6Other gases than ai
41、r may be used when specified by therequestor. It is important that the electronic flowmeter is calibrated for thetest gas. Nitrogen is often preferred as having more uniform viscosity andlow water content.5.1.2 Flow ControlThe flow rate of air shall be regulatedupstream from the specimen by a mass f
42、low controller (flowcontrol method) or a back pressure regulator (pressure controlmethod), or both. The flow control shall be capable ofregulating air flow between 0.01 and 1000 cm3/min to 65%.Two test methods of flow control are required to adapt to awide range of specimen permeability:5.1.2.1 Test
43、 Method A, Flow Control ModeThis testmethod is preferred for high-permeability specimens (greaterthan about 0.1 darcy) that require flows in the range from 2 to1000 cm3/min and low specimen inlet pressures.The mass flowcontroller is set for the desired flow through the specimen. Itshall automaticall
44、y adjust its downstream pressure as needed tomaintain constant mass flow rate of air regardless of tempera-ture or pressure.5.1.2.2 Test Method B, Pressure Control ModeThis testmethod is preferred for low-permeability specimens (less thanabout 0.1 darcy) that require control of pressure between 5 an
45、d35 kPa (1 and 5 psi) at low flow rates: The back pressureregulator shall act as a variable pressure relief valve that can beadjusted to produce a fixed inlet pressure. The mass flowcontroller is set to produce an airflow slightly in excess of thetest maximum.NOTE 7The back pressure regulator divert
46、s to the atmosphere aportion of the flow to maintain a constant inlet pressure to produce therequired specimen flow rate.FIG. 1 Pneumatic PermeameterD 6539 00 (2006)e135.2 Flow Measurement:5.2.1 The rate of air flowing into the specimen, Q, shall bemeasured to a precision better than 3 %. The prefer
47、red deviceis a digital electronic mass flowmeter upstream from thespecimen. If such a flowmeter is not available, a bubble meterat the outlet of the permeameter may be used.NOTE 8When repetitious, rapid measurements are required, the digi-tal electronic mass flowmeters will prove more convenient to
48、use than abubble meter, especially at high flow rates. The need for careful hand-eyecoordination technique is minimized, and the condition of constant flow iseasily recognized without recording repeated measurements. Electronicflowmeters measure the mass of gas flowing through the flowmeter. Thevolu
49、me of the gas at any point in the system is known from Boyles Law,given the pressure and temperature at that point. Flowmeters are insensi-tive to temperature and pressure changes over the range of operatingconditions specified by the manufacturer. Flowmeters are sensitive to thecomposition of the gas flowing through the flowmeters and their sensingelements are subject to long-term drift. For this reason, flowmeters mustbe installed upstream from the specimen where they will not be exposedto any moisture or trace volatiles that may be expel
