1、Designation: D 6391 06Standard Test Method forField Measurement of Hydraulic Conductivity Limits ofPorous Materials Using Two Stages of Infiltration from aBorehole1This standard is issued under the fixed designation D 6391; the number immediately following the designation indicates the year oforigin
2、al adoption 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.1. Scope1.1 This test method covers field measurement of limitingvalues for
3、vertical and horizontal hydraulic conductivities (alsoreferred to as coeffcients of permeability) of porous materialsusing the two-stage, cased borehole technique. These limitinghydraulic conductivity values are the maximum possible forthe vertical direction and minimum possible for the horizontaldi
4、rection. Determination of actual hydraulic conductivity val-ues requires further analysis by qualified personnel.1.2 This test method may be utilized for compacted fills ornatural deposits, above or below the water table, that have amean hydraulic conductivity less than or equal to 13105m/s(13103cm/
5、s).1.3 Hydraulic conductivity greater than 13105m/s may bedetermined by ordinary borehole tests, for example, U.S.Bureau of Reclamation 7310 (1)2; however, the resulting valueis an apparent conductivity.1.4 For this test method, a distinction must be made between“saturated” (Ks) and “field-saturated
6、” (Kfs) hydraulic conduc-tivity. True saturated conditions seldom occur in the vadosezone except where impermeable layers result in the presence ofperched water tables. During infiltration events or in the eventof a leak from a lined pond, a “field-saturated” conditiondevelops. True saturation does
7、not occur due to entrapped air(2). The entrapped air prevents water from moving in air-filledpores that, in turn, may reduce the hydraulic conductivitymeasured in the field by as much as a factor of two comparedwith conditions when trapped air is not present (3). This testmethod simulates the “field
8、-saturated” condition.1.5 Experience with this test method has been predomi-nantly in materials having a degree of saturation of 70 % ormore, and where the stratification or plane of compaction isrelatively horizontal. Its use in other situations should beconsidered experimental.1.6 As in the case o
9、f all tests for hydraulic conductivity, theresults of this test pertain only to the volume of soil permeated.Extending the results to the surrounding area requires bothmultiple tests and the judgment of qualified personnel. Thenumber of tests required depends on among other things: thesize of the ar
10、ea, the uniformity of the material in that area, andthe variation in data from multiple tests.1.7 The values stated in SI units are to be regarded as thestandard unless other units specifically are given. By traditionin U.S. practice, hydraulic conductivity is reported in cm/salthough the common SI
11、units for hydraulic conductivity arem/s.1.8 All observed and calculated values shall conform to theguide for significant digits and rounding established in PracticeD 6026.1.8.1 The procedures in this standard that are used to specifyhow data are collected, recorded, and calculated are regardedas the
12、 industry standard. In addition, they are representative ofthe significant digits that should generally be retained. Theprocedures do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the objectives of the user. Increasing or reducing
13、 thesignificant digits of reported data to be commensurate withthese considerations is common practice. Consideration of thesignificant digits to be used in analysis methods for engineeringdesign is beyond the scope of this standard.1.9 This standard does not purport to address the safetyconcerns, i
14、f any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use. This test method does not purport toaddress environmental protection problems, as well.2. Re
15、ferenced Documents2.1 ASTM Standards:3D 653 Terminology Relating to Soil, Rock, and ContainedFluids1This test 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 a
16、pproved Feb. 1, 2006. Published March 2006. Originallyapproved in 1999. Last previous edition approved in 2004 as D 6391 - 99(2004).2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or
17、contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.D 1452 Practice fo
18、r Soil Investigation and Sampling byAuger BoringsD 1587 Practice for Thin-Walled Tube Sampling of Soilsfor Geotechnical PurposesD 2937 Test Method for Density of Soil in Place by theDrive-Cylinder MethodD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of
19、Soil and Rockas Used in Engineering Design and ConstructionD 5084 Test Methods for Measurement of Hydraulic Con-ductivity of Saturated Porous Materials Using a FlexibleWall PermeameterD 5092 Practice for Design and Installation of GroundWater Monitoring WellsD 6026 Practice for Using Significant Dig
20、its in Geotechni-cal Data3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, see Terminology D 653.3.2 Definitions of Terms Specific to This Standard:3.2.1 horizontal conductivity, kh, nthe hydraulic conduc-tivity in (approximately) the horizontal direction.3.2.2 hydraulic
21、 conductivity, (coeffcient of permeability) k,nthe rate of discharge of water under laminar flow conditionsthrough a unit cross-sectional area of a porous medium undera unit hydraulic gradient and standard temperature conditions(20C).3.2.2.1 DiscussionThe term coeffcient of permeabilityoften is used
22、 instead of hydraulic conductivity, but hydraulicconductivity is used exclusively in this test method. A morecomplete discussion of the terminology associated with Dar-cys law is given in the literature (4). It should be noted thatboth natural soils and recompacted soils usually are notisotropic wit
23、h respect to hydraulic conductivity. Except forunusual materials, kh kv.3.2.3 limiting horizontal conductivity, K2, nthe hydraulicconductivity as determined in Stage 2 of this test method,assuming the tested medium to be isotropic. For ordinary soils,both compacted and natural, this is the minimum p
24、ossiblevalue for kh.3.2.4 limiting vertical conductivity, K1, nthe hydraulicconductivity as determined in Stage 1 of this test method,assuming the tested medium to be isotropic. For ordinary soils,both compacted and natural, this is the maximum possiblevalue for kv.3.2.5 test diameter, nthe inside d
25、iameter (ID) of thecasing.3.2.6 vertical conductivity, kv, nthe hydraulic conductiv-ity in (approximately) the vertical direction.4. Summary of Test Method4.1 The rate of flow of water into soil through the bottom ofa sealed, cased borehole is measured in each of two stages,normally with a standpipe
26、 in the falling-head procedure. Thestandpipe can be refilled as necessary.4.2 In Stage 1, the bottom of the borehole is flush with thebottom of the casing for maximum effect of kv. The test iscontinued until the flow rate becomes quasi-steady.4.3 For Stage 2, the borehole is extended below the botto
27、mof the casing for maximum effect of kh. This stage of the testalso is continued until the flow rate becomes quasi-steady.4.4 The direct results of the test are the limiting hydraulicconductivities K1 and K2. The actual hydraulic conductivitieskvand khcan be calculated from these values (5).5. Signi
28、ficance and Use5.1 This test method provides a means to measure both themaximum vertical and minimum horizontal hydraulic conduc-tivities, especially in the low ranges associated with fine-grained clayey soils, 13107m/s to 131011m/s.5.2 This test method particularly is useful for measuringliquid flo
29、w through soil moisture barriers, such as compactedclay liners or covers used at waste disposal facilities, for canaland reservoir liners, for seepage blankets, and for amended soilliners, such as those used for retention ponds or storage tanks.Due to the boundary condition assumptions used in deriv
30、ingthe equations for the limiting hydraulic conductivities, thethickness of the unit tested must be at least six times the testdiameter. This requirement must be increased to eight testdiameters if the barrier is not underlain by a drainage blanketor by a material far less permeable than the barrier
31、 being tested.5.3 The soil layer being tested must have sufficient cohesionto stand open during excavation of the borehole.5.4 This test method provides a means to measure infiltra-tion rate into a moderately large volume of soil. Tests on largevolumes of soil can be more representative than tests o
32、n smallvolumes of soil. Multiple installations properly spaced providea greater volume and an indication of spatial variability.5.5 The data obtained from this test method are most usefulwhen the soil layer being tested has a uniform distribution ofhydraulic conductivity and of pore space and when t
33、he upperand lower boundary conditions of the soil layer are welldefined.5.6 Changes in water temperature can introduce significanterrors in the flow measurements. Temperature changes causefluctuations in the standpipe levels, which are not related toflow. This problem is most pronounced when a small
34、 diameterstandpipe is used in soils having hydraulic conductivities of531010m/s or less.5.7 The effects of temperature changes are taken intoaccount by the use of a dummy installation, the temperatureeffect gage (TEG). The base of the TEG must be sealed toprevent flow. The fluctuations of the TEG ar
35、e due solely toambient changes and are used to correct the readings at theflowing tests.5.8 If the soil being tested will later be subjected toincreased overburden stress, then the hydraulic conductivitiescan be expected to decrease as the overburden stress increases.Laboratory hydraulic conductivit
36、y tests or these tests undervarying surface loads are recommended for studies of theinfluence of level of stress on the hydraulic properties of thesoil.NOTE 1Notwithstanding the statements on precision and bias con-tained in this standard: the precision of this test method is dependent onthe compete
37、nce of the personnel performing it and the suitability of theequipment and the facilities used. Agencies that meet the criteria ofPractice D 3740 are generally considered capable of competent andD6391062objective testing. Users of this test method are cautioned that compliancewith Practice D 3740 do
38、es not in itself assure reliable testing. Reliabletesting depends on many factors; Practice D 3740 provides a means ofevaluating some of those factors.6. Apparatus6.1 Boring/Reaming Tools:6.1.1 Drilling EquipmentEquipment must be available toadvance the borehole to the desired test level. This boreh
39、olediameter must be at least 5 cm (2 in.) larger than the outsidediameter of the casing. The auger or bit used to advance theborehole below the casing for Stage 2 shall have a diameterabout 1 cm (12 in.) less than the inside diameter of the casing.For tests in compacted materials above the water tab
40、le, andwherever else possible, the borehole shall be advanced by dryaugering. Either hand or mechanical augers are acceptable.6.1.2 Flat AugerThe flat auger (see Fig. 1) is used toprepare the borehole for casing installation. It shall be capableof reaming the bottom of the borehole to a level planep
41、erpendicular to the borehole axis. The flat auger shall have adiameter about 5 cm (2 in.) larger than the outside diameter ofthe casing.6.1.3 ReamerThe reamer (see Fig. 1) is used to completethe Stage 2 cavity. The base of the reamer shall have a diameterslightly less than the inside diameter of the
42、 casing and shall becapable of reaming the bottom of the advanced borehole to alevel plane that is perpendicular to the primary axis of theborehole. The bottom plate of the reamer shall have a diameterabout 0.1 cm (0.04 in.) less than the inside diameter of thecasing. The vertical side of the cuttin
43、g plate shall be serrated.6.1.4 ScarifierA bent fork, wire brush, or similar rough-ener small enough to fit easily within the casing and having ahandle long enough to reach the bottom of Stage 2, is used toroughen the walls of the Stage 2 cavity.6.2 Borehole Casing:6.2.1 CasingThe casing shall be wa
44、tertight but may be ofany material or diameter. Its minimum ID shall be 10 cm (4 in.)unless the clearance provisions specified in 7.7 cannot be met.In such cases only, the ID may be reduced to 7.5 cm (3 in.). Thewall thickness shall be adequate to prevent collapse under thelateral pressure of the ov
45、erburden and swelling bentonite.Standard 10-cm (4-in.) ID Schedule 40 PVC threaded pipe issatisfactory. The bottom of the casing shall be cut off smoothand square. The casing shall have flush threads; externalcouplers interfere with sealing the annulus and internal cou-plers with advancing the boreh
46、ole for Stage 2. Neither shall beused. The top of the casing shall be provided with a means ofattaching the top assembly. Typical modifications includethreading the top or attaching a flange. When threads are used,they must be flush. When a flange is used, the diameter shall beminimal so as not to i
47、nterfere with sealing the annulus. Anycasing joints and joint between top assembly and casing shallbe provided with an O-Ring or other device to ensure water-tightness.6.2.2 Top AssemblyThis consists of a cap attached (nor-mally by gluing) to a short piece of threaded casing, asillustrated in Fig. 2
48、. The cap shall be domed or slanted upwardsto minimize air entrapment. It shall be fabricated so as toreceive the flow control system with a watertight joint. Provi-sions for bleeding any entrapped air shall be made. For theTEG (only), the top assembly also may be provided with awatertight fitting f
49、or the thermometer or thermocouple leads.6.2.3 Annular SealantBentonite is normally used to sealthe annulus between the wall of the borehole and the wall ofthe casing. All sealants should be compatible with ambientgeologic and geohydrologic conditions. Do not introduce anysealants into the casing.6.2.3.1 Directly Placed SealantThe annular sealant is bestplaced in the borehole dry and tamped for shallow installations.Bentonite should be granular or pelletized, sodium montmoril-lonite furnished in sacks or buckets from a commercial sourceand free of impurities
