ASTM D5881-1995(2005) Standard Test Method for (Analytical Procedure) Determining Transmissivity of Confined Nonleaky Aquifers by Critically Damped Well Response to Instantaneous C.pdf
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1、Designation: D 5881 95 (Reapproved 2005)Standard Test Method for(Analytical Procedure) Determining Transmissivity ofConfined Nonleaky Aquifers by Critically Damped WellResponse to Instantaneous Change in Head (Slug)1This standard is issued under the fixed designation D 5881; the number immediately f
2、ollowing the designation indicates the year oforiginal 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 me
3、thod covers determination of transmissivityfrom the measurement of water-level response to a suddenchange of water level in a well-aquifer system characterized asbeing critically damped or in the transition range from under-damped to overdamped. Underdamped response is character-ized by oscillatory
4、changes in water level; overdamped re-sponse is characterized by return of the water level to the initialstatic level in an approximately exponential manner. Over-damped response is covered in Guide D 4043; underdampedresponse is covered in D 5785.1.2 The analytical procedure in this test method is
5、used inconjunction with Guide D 4043 and the field procedure in TestMethod D 4044 for collection of test data.1.3 LimitationsSlug tests are considered to provide anestimate of the transmissivity of an aquifer near the wellscreen. The method is applicable for systems in which thedamping parameter, z,
6、 is within the range from 0.2 through 5.0.The assumptions of the method prescribe a fully penetratingwell (a well open through the full thickness of the aquifer) ina confined, nonleaky aquifer.1.4 The values stated in SI units are to be regarded asstandard.1.5 This standard does not purport to addre
7、ss 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminolo
8、gy Relating to Soil, Rock, and ContainedFluidsD 4043 Guide for Selection of Aquifer-Test Method inDetermining of Hydraulic Properties by Well TechniquesD 4044 Test Method (Field Procedure) for InstantaneousChange in Head (Slug Test) for Determining HydraulicProperties of AquifersD 4750 Test Method f
9、or Determining Subsurface LiquidLevels in a Borehole or Monitoring Well (ObservationWell)D 5785 Test Method for (Analytical Procedure) Determin-ing Transmissivity of Confined Nonleaky Aquifers byUnderdamped Well Response to Instantaneous Change inHead (Slug Test)3. Terminology3.1 Definitions:3.1.1 a
10、quifer, confinedan aquifer bounded above andbelow by confining beds and in which the static head is abovethe top of the aquifer.3.1.2 confining beda hydrogeologic unit of less perme-able material bounding one or more aquifers.3.1.3 control wella well by which the head and flow in theaquifer is chang
11、ed by pumping, injecting, or imposing aconstant change of head.3.1.4 critically damped well responsecharacterized by thewater level responding in a transitional range between under-damped and overdamped following a sudden change in waterlevel.3.1.5 head, staticthe height above a standard datum thesu
12、rface of a column of water can be supported by the staticpressure at a given point.3.1.6 observation wella well open to all or part of anaquifer.3.1.7 overdamped well responsecharacterized by the wa-ter level returning to the static level in an approximatelyexponential manner following a sudden chan
13、ge in water level.(See for comparison underdamped well response.)3.1.8 sluga volume of water or solid object used to inducea sudden change of head in a well.1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Gro
14、und Water andVadose Zone Investigations.Current edition approved Nov. 1, 2005. Published December 2005. Originallyapproved in 1995. Last previous edition approved in 2000 as D 5881 95 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
15、iceastm.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.3.1.9 storage coeffcientthe volume of water an aquiferr
16、eleases from or takes into storage per unit surface area of theaquifer per unit change in head. For a confined aquifer, thestorage coefficient is equal to the product of the specific storageand aquifer thickness.3.1.10 transmissivitythe volume of water at the existingkinematic viscosity that will mo
17、ve in a unit time under a unithydraulic gradient through a unit width of the aquifer.3.1.11 underdamped well responseresponse characterizedby the water level oscillating about the static water levelfollowing a sudden change in water level (See for comparisonoverdamped-well response).3.1.12 For defin
18、itions of other terms used in this testmethod, see Terminology D 653.3.2 Symbols:Symbols and Dimensions:3.2.1 Ttransmissivity L2T1.3.2.2 Sstorage coefficient nd.3.2.3 Lstatic water column length above top of aquiferL.3.2.4 Leeffective length of water column in a well, equalto Lc+(rc2/rs2)(b/2) L.3.2
19、.5 Lclength of water column within casing L.3.2.6 Lslength of water column within well screen L.3.2.7 gacceleration of gravity LT2.3.2.8 hhydraulic head in the aquifer L.3.2.9 hoinitial hydraulic head in the aquifer L.3.2.10 hshydraulic head in the well screen L.3.2.11 rcradius of well casing L.3.2.
20、12 rsradius of well screen L.3.2.13 ttime T.3.2.14 t8dimensionless time nd.3.2.15 tdimensionless time nd.3.2.16 wwater level displacement from the initial staticlevel L.3.2.17 woinitial water level displacement L.3.2.18 adimensionless storage parameter nd.3.2.19 bdimensionless inertial parameter nd.
21、3.2.20 gdamping constant T1.3.2.21 twavelength T.3.2.22 vangular frequency T1.3.2.23 zdimensionless damping factor nd.4. Summary of Test Method4.1 This test method describes the analytical procedure foranalyzing data collected during an instantaneous head (slug)test for well and aquifer response at
22、and near critical damping.Procedures in conducting a slug test are given in Test MethodD 4044. The analytical procedure consists of analyzing theresponse of water level in the well following the change inwater level induced in the well.4.2 TheoryThe equations that govern the response of wellto an in
23、stantaneous change in head are treated at length byKipp (1).3The flow in the aquifer is governed by the followingequation for cylindrical flow:STdhdt51rddrSrdhdrD(1)where:h = hydraulic head,T = aquifer transmissivity, andS = storage coefficient.4.2.1 The initial condition is at t = 0 and h = ho, and
24、 theouter boundary condition is as r and hho.4.2.1.1 An equation is given by Kipp (1) for the skin factor,that is, the effect of aquifer damage during drilling of the well.However, this factor is not treated by Kipp (1) and is notconsidered in this procedure.4.2.2 The flow rate balance on the well b
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