ASTM D5785-1995(2006) Standard Test Method for (Analytical Procedure) for Determining Transmissivity of Confined Nonleaky Aquifers by Underdamped Well Response to Instantaneous Cha.pdf
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1、Designation: D 5785 95 (Reapproved 2006)Standard Test Method for(Analytical Procedure) for Determining Transmissivity ofConfined Nonleaky Aquifers by Underdamped WellResponse to Instantaneous Change in Head (Slug Test)1This standard is issued under the fixed designation D 5785; the number immediatel
2、y following 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
3、 method covers determination of transmissivityfrom the measurement of the damped oscillation about theequilibrium water level of a well-aquifer system to a suddenchange of water level in a well. Underdamped response ofwater level in a well to a sudden change in water level ischaracterized by oscilla
4、tory fluctuation about the static waterlevel with a decrease in the magnitude of fluctuation andrecovery to initial water level. Underdamped response mayoccur in wells tapping highly transmissive confined aquifersand in deep wells having long water columns.1.2 This analytical procedure is used in co
5、njunction with thefield procedure Test Method D 4044 for collection of test data.1.3 LimitationsSlug tests are considered to provide anestimate of transmissivity of a confined aquifer. This testmethod requires that the storage coefficient be known. As-sumptions of this test method prescribe a fully
6、penetrating well(a well open through the full thickness of the aquifer), but theslug test method is commonly conducted using a partiallypenetrating well. Such a practice may be acceptable forapplication under conditions in which the aquifer is stratifiedand horizontal hydraulic conductivity is much
7、greater thanvertical hydraulic conductivity. In such a case the test would beconsidered to be representative of the average hydraulicconductivity of the portion of the aquifer adjacent to the openinterval of the well. The method assumes laminar flow and isapplicable for a slug test in which the init
8、ial water-leveldisplacement is less than 0.1 or 0.2 of the length of the staticwater column.1.4 This test method of analysis presented here is derived byvan der Kamp (1)2based on an approximation of the under-damped response to that of an exponentially damped sinusoid.A more rigorous analysis of the
9、 response of wells to a suddenchange in water level by Kipp (2) indicates that the methodpresented by van der Kamp (1) matches the solution of Kipp(2) when the damping parameter values are less than about 0.2and time greater than that of the first peak of the oscillation (2).1.5 This standard does n
10、ot 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 limitations prior to use.2. Referenced Documents2.1 ASTM Standar
11、ds:3D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 4043 Guide for Selection of Aquifer Test Method inDetermining Hydraulic Properties by Well TechniquesD 4044 Test Method (Field Procedure) for InstantaneousChange in Head (Slug) Tests for Determining HydraulicProperties of Aquifiers3.
12、 Terminology3.1 Definitions:3.1.1 aquifer, 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 wellwell by which the aqu
13、ifer is stressed, forexample, by pumping, injection, or change in head.3.1.4 head, staticthe height above a standard datum of thesurface of a column of water (or other liquid) that can besupported by the static pressure at a given point.3.1.5 observation wella well open to all or part of anaquifer.3
14、.1.6 overdamped well responsecharacterized by the wa-ter level returning to the static level in an approximatelyexponential manner following a sudden change in water level.(See for comparison underdamped well response.)1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock
15、and is the direct responsibility of Subcommittee D18.21 on Ground Water andVadose Zone Investigations.Current edition approved Sept. 15, 2006. Published December 2006. Originallyapproved in 1995. Last previous edition approved in 2000 as D 5785 95 (2000).2The boldface numbers given in parentheses re
16、fer to a list of references at theend of the text.3For 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.1Copyright
17、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.7 sluga volume of water or solid object used to inducea sudden change of head in a well.3.1.8 storage coeffcientthe volume of water an aquiferreleases from or takes into storage per unit surfa
18、ce area of theaquifer per unit change in head. For a confined aquifer, thestorage coefficient is equal to the product of specific storageand aquifer thickness. For an unconfined aquifer, the storagecoefficient is approximately equal to the specific yield.3.1.9 transmissivitythe volume of water at th
19、e existingkinematic viscosity that will move in a unit time under a unithydraulic gradient through a unit width of the aquifer.3.1.10 underdamped well responseresponse characterizedby the water level oscillating about the static water levelfollowing a sudden change in water level (See for comparison
20、overdamped well response.)3.1.11 For definitions of other terms used in this testmethod, see Terminology D 653.3.2 Symbols and Dimensions:3.2.1 Ttransmissivity L2T1.3.2.2 Sstorage coefficient nd.3.2.3 Leffective length of water column, equal to Lc+( rc2/rs2) (m/2).3.2.3.1 DiscussionThis expression f
21、or the effective lengthis given by Kipp (2). The expression for the effective length ofthe water column from Cooper et al (3) is given as Lc+ 3/8Lsand assumes that the well screen and well casing have the samediameter.3.2.4 Lclength of water column within casing L.3.2.5 Lslength of water column with
22、in well screen L.3.2.6 gacceleration of gravity LT2.3.2.7 hhydraulic head in the aquifer L.3.2.8 hoinitial hydraulic head in the aquifer L.3.2.9 hshydraulic head in the well screen L.3.2.10 rcradius of well casing L.3.2.11 rsradius of well screen L.3.2.12 ttime T.3.2.13 wwater level displacement fro
23、m the initial staticlevel L.3.2.14 woinitial water level displacement L.3.2.15 gdamping constant T1.3.2.16 twavelength T.3.2.17 vangular frequency T1.3.2.18 maquifer thickness, L.4. Summary of Test Method4.1 This test method describes the analytical procedure foranalyzing data collected during an in
24、stantaneous head (slug)test using a well in which the response is underdamped. Thefield procedures in conducting a slug test are given in TestMethod D 4044.The analytical procedure consists of analyzingthe response of water level in the well following the change inwater level induced in the well.4.2
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