1、Designation: D5920 14Standard Test Method (Analytical Procedure) forTests of Anisotropic Unconfined Aquifers by NeumanMethod1This standard is issued under the fixed designation D5920; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 an analytical procedure fordetermining the transmissivity, storage coefficient,
3、specificyield, and horizontal-to-vertical hydraulic conductivity ratio ofan unconfined aquifer. It is used to analyze the drawdown ofwater levels in piezometers and partially or fully penetratingobservation wells during pumping from a control well at aconstant rate.1.2 The analytical procedure given
4、 in this test method isused in conjunction with Guide D4043 and Test MethodD4050.1.3 The valid use of the Neuman method is limited todetermination of transmissivities for aquifers in hydrogeologicsettings with reasonable correspondence to the assumptions ofthe theory.1.4 The values stated in SI unit
5、s are to be regarded asstandard.1.5 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 and health practices and determine the applica-bility of regulatory limitati
6、ons prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4043 Guide for Selection of
7、Aquifer Test Method inDetermining Hydraulic Properties by Well TechniquesD4050 Test Method for (Field Procedure) for Withdrawaland Injection Well Tests for Determining Hydraulic Prop-erties of Aquifer SystemsD4105 Test Method for (Analytical Procedure) for Deter-mining Transmissivity and Storage Coe
8、fficient of Non-leaky Confined Aquifers by the Modified Theis Nonequi-librium MethodD4106 Test Method for (Analytical Procedure) for Deter-mining Transmissivity and Storage Coefficient of Non-leaky Confined Aquifers by the Theis NonequilibriumMethodD6026 Practice for Using Significant Digits in Geot
9、echnicalData3. Terminology3.1 DefinitionsFor definitions of general technical termsused within this guide, refer to Terminology D653.3.2 Symbols and Dimensions:3.2.1 b Linitial saturated thickness of the aquifer.3.2.2 d Lvertical distance between top of screen inpumping well and initial position of
10、the water table.3.2.3 dDnddimensionless d, equal to d/b.3.2.4 J0(x)zero-order Bessel function of the first kind.3.2.5 KrLT1hydraulic conductivity in the plane of theaquifer, radially from the control well.3.2.6 KZLT1hydraulic conductivity normal to the planeof the aquifer.3.2.6.1 DiscussionThe use o
11、f the symbol K for the hy-draulic conductivity is the predominant usage in groundwaterliterature by hydrogeologists, whereas, the symbol k is com-monly used for this term in soil and rock mechanics and soilscience.3.2.7 l Lvertical distance between bottom of screen incontrol well and initial positio
12、n of water table.3.2.8 lDnddimensionless l, equal to l/b.3.2.9 QL3T1discharge rate.3.2.10 r Lradial distance from control well.3.2.11 s Ldrawdown.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Groundwater an
13、dVadose Zone Investigations.Current edition approved June 1, 2014. Published July 2014. Originally approvedin 1996. Last previous edition approved in 2006 as D5920-96(2006), which waswithdrawn February 2014 and reinstated in June 2014. DOI: 10.1520/D5920-14.2For referenced ASTM standards, visit the
14、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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr
15、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.12 scLcorrected drawdown.3.2.13 sDnddimensionless drawdown, equal to 4Ts/Q.3.2.14 swtLdrawdown of the water table.3.2.15 S ndstorage coefficient, equal to Ssb.3.2.16 SsL1specific storage.3.2.17 Syndspecific yield.3.2.18
16、t Ttime since pumping started.3.2.19 trTtime since recovery started.3.2.20 tsnddimensionless time with respect to Ss, equalto Tt/Sr2.3.2.21 tynddimensionless time with respect to Sy, equalto Tt/Syr2.3.2.22 tTtime, t, corresponding to intersection of ahorizontal line through the intermediate data wit
17、h an inclinedline through late data on semilogarithmic paper.3.2.23 tynddimensionless time, ty, corresponding to theintersection of a horizontal line through intermediate data withan inclined line through late data in Fig. 1.3.2.24 (t/r2)eTt/r2corresponding to the intersection of astraight line thro
18、ugh the early data with s = 0 on semilogarith-mic paper TL2.3.2.25 (t/r2)lTt/r2corresponding to the intersection of astraight line through the late data with s = 0 on semilogarith-mic paper.3.2.26 TL2T1transmissivity, Krb.3.2.27 z Lvertical distance above the bottom of theaquifer.3.2.28 z1Lvertical
19、distance of the bottom of the obser-vation well screen above the bottom of the aquifer.3.2.29 z2Lvertical distance of the top of the observationwell screen above the bottom of the aquifer.3.2.30 zDnddimensionless elevation, equal to z/b.3.2.31 z1Dnddimensionless elevation of base of screen,equal to
20、z1/b.3.2.32 z2Dnddimensionless elevation of top of screen,equal to z2/b.3.2.33 degree of anisotropy, equal to Kz/Kr.3.2.34 nddimensionless parameter r2/b2.3.2.35 seLthe difference in drawdown over one logcycle of time along a straight line through early data onsemilogarithmic paper.3.2.36 slLthe dif
21、ference in drawdown over one logcycle of time along a straight line through late data onsemilogarithmic paper.3.2.37 nddimensionless parameter S/Sy.4. Summary of Test Method4.1 ProcedureThis test method describes a procedure foranalyzing data collected during a withdrawal well test. Thistest method
22、should have been selected using Guide D4043 onthe basis of the hydrologic characteristics of the site. The fieldtest (Test Method D4050) requires pumping a control well thatis open to all or part of an unconfined aquifer at a constant ratefor a specified period and observing the drawdown in piezom-e
23、ters or observation wells that either partly or fully penetratethe aquifer. This test method may also be used to analyze aninjection test with the appropriate change in sign. The rate ofdrawdown of water levels in the aquifer is a function of thelocation and depths of screened open intervals of the
24、controlwell, observation wells, and piezometers. The drawdown maybe analyzed to determine the transmissivity, storage coefficient,FIG. 1 Aquifer-Test Analysis, Example TwoD5920 142specific yield, and ratio of vertical to horizontal hydraulicconductivity of the aquifer. The accuracy with which anypro
25、perty can be determined depends on the location and lengthof the well screen in observation wells and piezometers. Twomethods of analysis, a type curve method and a semilogarith-mic method, are described.4.2 SolutionThe solution given by Neuman (1)3can beexpressed as:sr, z, t! 5Q4T*04yJ0y1/2!Fu0y!1(
26、n51uny!Gdy (1)where, for piezometers, Neumans (1) Eqs 27 and 28 are asfollows:sinh01 2 dD!# 2 sinh01 2 lD!#lD2 dD!sinh0!and:uny! 5$1 2 exp2tsy21n2!#%cosnzD!$y22 11!n22 y21n2!2/% n(3)sin n1 2 dD!# 2 sin n1 2 lD!#lD2 dD!sinn!and the terms 0and nare the roots of the followingequations:0sinh0!2 y22 02!c
27、osh0! 5 0 (4)02,y2nsinn!1y21n2!cosn! 5 0 (5)2n 2 1!/2!,n,n n $14.2.1 The drawdown in an observation well is the averageover the screened interval, of which u0(y) and un(y) aredescribed by Neumans (1) Eqs 29 and 30:u0y! 5$1 2 exp2tsy22 02!#% sinh0z2D! 2 sinh0z1D!#$sinh01 2 dD!# 2 sinh01 2 lD!#%$y2111
28、! 022 y22 02!2/%cosh0!z2D2 z1D!0lD2 dD!sinh0!(6)uny! 5$1 2 exp2tsy21n2!#% sin nz2D! 2 sin nz1D!#$ sin n1 2 dD!# 2 sin n1 2 lD!#%$y22 11!n22 y21n2!2/%cosn!z2D2 z1D!nlD2 dD!sinn!(7)4.2.2 In the case in which the control well and observationwell fully penetrate the aquifer, the equations reduce toNeuma
29、ns (1) Eqs 2 and 3 as follows:u0y! 5$1 2 exp2tsy22 02!#%tanh0!$y2111! 022 y22 02!2/#%0(8)and:uny! 5$1 2 exp2tsy21n2!#%tann!$y22 11! n22y21n2!2/%n(9)5. Significance and Use5.1 Assumptions:5.1.1 The control well discharges at a constant rate, Q.5.1.2 The control well, observation wells, and piezometer
30、sare of infinitesimal diameter.5.1.3 The unconfined aquifer is homogeneous and reallyextensive.5.1.4 Discharge from the control well is derived initiallyfrom elastic storage in the aquifer, and later from gravitydrainage from the water table.5.1.5 The geometry of the aquifer, control well, observati
31、onwells, and piezometers is shown in Fig. 2. The geometry of thetest wells should be adjusted depending on the parameters ofinterest.5.2 Implications of Assumptions:5.2.1 Use of the Neuman (1) method assumes the controlwell is of infinitesimal diameter. The storage in the control wellmay adversely a
32、ffect drawdown measurements obtained in theearly part of the test. See 5.2.2 of Test Method D4106 forassistance in determining the duration of the effects of well-bore storage on drawdown.5.2.2 If drawdown is large compared with the initial satu-rated thickness of the aquifer, the late-time drawdown
33、 mayneed to be adjusted for the effect of the reduction in saturatedthickness. Section 5.2.3 of Test Method D4106 providesguidance in correcting for the reduction in saturated thickness.According to Neuman (1) such adjustments should be madeonly for late-time values.5.3 Practice D3740 provides evalu
34、ation factors for theactivities in this guide.NOTE 1The quality of the result produced by this guide is dependenton the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of PracticeD3740 are generally considered capabl
35、e of competent and objectivetesting/sampling/inspection/etc. Users of this guide are cautioned thatcompliance with Practice D3740 does not in itself ensure reliable results.Reliable results depend on many factors; Practice D3740 provides a means3The boldface numbers in parentheses refer to a list of
36、 references at the end ofthe text.FIG. 2 Cross Section Through a Discharging Well Screened inPart of an Unconfined AquiferD5920 143of evaluating some of those factors.6. Apparatus6.1 AnalysisAnalysis of data from the field procedure (seeTest Method D4050) by this test method requires that thecontrol
37、 well and observation wells meet the requirementsspecified in the following subsections.6.2 Construction of Control WellInstall the control well inthe aquifer, and equip with a pump capable of dischargingwater from the well at a constant rate for the duration of thetest.6.3 Construction of Observati
38、on Wells Construct one ormore observation wells or piezometers at a distance from thecontrol well. For this test method, observation wells may beopen through all or part of the thickness of the aquifer.6.4 Location of Observation Wells Wells may be locatedat any distance from the control well within
39、 the area ofinfluence of pumping.7. Procedure7.1 ProcedureThe procedure consists of conducting thefield procedure for withdrawal well tests (see Test MethodD4050), and analyzing the field data as addressed in this testmethod.7.2 AnalysisAnalyze the field test data by plotting the dataand recording p
40、arameters as specified in Section 8.8. Calculation and Interpretation of Results8.1 MethodsThe drawdown data collected during theaquifer test may be analyzed by either the type-curve methodor the semilogarithmic method.Any consistent set of units maybe used.8.1.1 Refer to Practice D6026 on the use o
41、f significant digitsin the calculations.NOTE 2The procedures used to specify how data are collected/recorded and calculated in this guide are regarded as the industry standard.In addition, they are representative of the significant digits that shouldgenerally be retained. The procedures used do not
42、consider materialvariation, purpose for obtaining the data, special purpose studies, or anyconsiderations for the users objectives; and it is common practice toincrease or reduce significant digits of reported data to commensurate withthese considerations. It is beyond the scope of this guide to con
43、sidersignificant digits used in analysis methods for engineering design.8.1.2 Type-Curve MethodPlot drawdown, s, on the verti-cal axis and time divided by the square of the radius to the wellor piezometer, t/r2, on the horizontal axis using log-log paper.Group data for all wells or piezometers that
44、have screenedintervals the same elevation above the base of the aquifer, zD(for piezometers), or z1Dand z2D(for observation wells).8.1.2.1 Prepare a family of type curves for different valuesof . For tests in which both the control well and theobservation wells fully penetrate the aquifer, the value
45、s inTable 1 and Table 2 may be used to prepare the type curves, asshown in Fig. 3. For piezometers, or tests in which the controlwell or observation wells do not effectively penetrate the fullthickness of the aquifer, the values of sDcorresponding tovalues of tsand tyfor a range of values of must be
46、 computedusing computer programs such as those of Dawson and Istok(2), or Moench (3) . The program requires that values for thedimensionless parameters lDand dDbe supplied for the controlwell, and values of zDbe supplied for the piezometers, or thatthe values of z1Dand z2Dbe supplied for observation
47、 wells.Only drawdowns for which these dimensionless parameters aresimilar may be analyzed using the same family of type curves.Prepare as many data plots and families of type curves asnecessary to analyze the test.8.1.2.2 Holding the axes parallel, overlay the data plot onthe type curves. Match as m
48、any of the early time-drawdowndata as possible to the left-most part of the type curve (Type Acurves). Select an early-time match point, and record the valuesof s, t/r2,sDand ts. Moving the data plot horizontally, match asmany as possible of the late-time data to the right-most part ofthe type curves (Type B curves) and select a late-time matchpoint. Record the values of s, sD, t/r2, and tyfor this matchpoint.The values of s and sDshould be the same for each matchpoint, that is, the data curves should be shifted onlyhorizontally, not vertically, on the type curve, and the values
