ASTM D5129-1995(2003) Standard Test Method for Open Channel Flow Measurement of Water Indirectly by Using Width Contractions《使用收缩宽度法迂回测量明渠水流流量的标准试验方法》.pdf
《ASTM D5129-1995(2003) Standard Test Method for Open Channel Flow Measurement of Water Indirectly by Using Width Contractions《使用收缩宽度法迂回测量明渠水流流量的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D5129-1995(2003) Standard Test Method for Open Channel Flow Measurement of Water Indirectly by Using Width Contractions《使用收缩宽度法迂回测量明渠水流流量的标准试验方法》.pdf(42页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 5129 95 (Reapproved 2003)Standard Test Method forOpen Channel Flow Measurement of Water Indirectly byUsing Width Contractions1This standard is issued under the fixed designation D 5129; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 the computation of discharge(the volume rate of flow) of water
3、in open channels or streamsusing bridges that cause width contractions as metering de-vices.21.2 This test method produces the maximum discharge forone flow event, usually a specific flood. The computed dis-charge may be used to help define the high-water portion of astage-discharge relation.1.3 The
4、 values stated in inch-pound units are to be regardedas the standard. The SI units given in parentheses are forinformation only.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
5、appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1129 Terminology Relating to Water3D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water3D 385
6、8 Test Method for Open Channel Flow Measurementsof Water by Velocity-Area Method32.2 ISO Standard:ISO 748 Liquid Flow Measurements in Open ChannelsVelocity-Area Measurements43. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 1129.3.2 Definitions of
7、Terms Specific to This Standard:3.2.1 alpha (a)a velocity-head coefficient that adjusts thevelocity head computed on basis of the mean velocity to thetrue velocity head.3.2.2 area (A) the area of a cross section, parts of a crosssection, or parts of bridges below the water surface. Subscriptsindicat
8、e specific areas as follows:Ai= area of subsection i,Aj= area of piers or piles that is submerged,A1= area of total cross section 1 (see Fig. 1), andA3= gross area of section 3.3.2.3 conveyance, (K)a measure of the carrying capacityof a channel cross section, or parts of a cross section, and hasunit
9、s of cubic feet per second or cubic metres per second.Conveyance is computed as follows:K 5*1.486nAR2/3where:n = the Manning roughness coefficient,A = the cross-section area, ft2(m2), andR = the hydraulic radius, ft (m).*in SI units = 1.0The following subscripts refer to specific conveyances forpart
10、s of a cross section:Ka,Kb= conveyances of parts of the approach section toeither side of the projected bottom width of thecontracted section (see Fig. 2). Kdis always thesmaller of the two,Kd= conveyance at the upstream end of the dikes,Ki= conveyance of subsection i,Kq= conveyance of the part of t
11、he approach sectioncorresponding to the projected bottom-width, andKT= total conveyance of cross section.3.2.4 depth (y)depth of flow at a cross section. Subscriptsdenote specific cross section depths as follows:1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the dir
12、ect responsibility of Subcommittee D19.07 on Sediments, Geomor-phology, and Open-Channel Flow.Current edition approved June 10, 2003. Published August 2003. Originallyapproved in 1990. Last previous edition approved in 1999 as D 5129 95 (1999).2This test method is similar to methods developed by the
13、 U.S. GeologicalSurvey and described in documents referenced in Footnote 5.3Annual Book of ASTM Standards, Vol 11.01.4Available from American National Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
14、n, PA 19428-2959, United States.y1= depth of flow in cross section 1(approach section),andy3= depth of flow in cross section 3(contracted section).3.2.5 eccentricity (e)a measure of the symmetry of thecontraction in relation to the approach channel.3.2.6 friction slope (Sf) the energy loss, hf, divi
15、ded by thelength of the reach, L.3.2.7 Froude number (F)an index to the state of flow in achannel. In a rectangular channel, the flow is tranquil orsubcritical if the Froude number is less than 1.0 and is rapid orsupercritical if it is greater than 1.0.3.2.8 head (h)static or piezometric head above
16、an arbi-trary datum. Subscripts indicate specific heads as follows:hf= head loss due to friction, andhs= stagnation-surface level at embankment face.3.2.9 hydraulic radius (R)is equal to the area of a crosssection or subsection divided by its wetted perimeter.3.2.10 length (L)length of bridge abutme
17、nt in direction offlow. Subscripts or symbols identify other lengths as follows:Ld= length of dikes,Lw= distance from approach section to upstream side ofcontraction,u = length of projection of abutment beyond wingwalljunction, andx = horizontal distance from the intersection of the abut-ment and em
18、bankment slopes to the location onupstream embankment having the same elevation asthe water surface at section 1.3.2.11 wetted perimeter (P)is the sum of the hypotenuseof a right triangle defined by the distance between adjacentstations of the cross section and the difference in bed eleva-tions.3.2.
19、12 width (b)width of contracted flow section. Sub-scripts denote specific widths as follows:bd= offset distance for straight dikes, andbt= width of contracted flow section at water surface.3.3 Symbols: Symbols:3.3.1 flow contraction ratio = m.3.3.2 coeffcientsC = coefficient of discharge,C8 = coeffi
20、cient of discharge for base condition,n = Manning roughness coefficient, andk = discharge coefficient adjustment.4. Summary of Test Method4.1 The contraction of a stream channel by a bridge createsan abrupt drop in water-surface elevation between an approachsection and the contracted section under t
21、he bridge that can berelated to the discharge using the bridge as a metering device.A field survey is made to determine distances between andelevations of high-water marks upstream and downstream fromthe contraction and the geometry of the bridge structure. Thesedata are used to compute the fall in
22、the water surface betweenan approach section and the contracted section and selectedproperties of the sections. This information is used along withdischarge coefficients, determined by extensive hydraulic labo-ratory investigations and verified at field sites, in a dischargeequation to compute the d
23、ischarge, Q.5. Significance and Use5.1 This test method is particularly useful to determine thedischarge when it cannot be measured directly by some type ofcurrent meter to obtain velocities and with sounding weights todetermine the cross section.5.2 Even under the best conditions, the personnel ava
24、ilablecannot cover all points of interest during a major flood. Theengineer or technician cannot always obtain reliable results bydirect methods if the stage is rising or falling very rapidly, ifflowing ice or debris interferes with depth or velocity measure-ments, or if the cross section of an allu
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