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1、BRITISH STANDARD BS 3680-10C: 1996 Measurement of liquid flow in open channels Part 10: Sediment transport Part 10 C: Guide to methods of sampling of sand-bed and cohesive-bed materials Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680
2、-10C:1996 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, was published under the authority of the Standards Board and comes into effect on 15 July 1996 BSI 07-1999 First published March 1980 Second edition July 1996 The following BSI references
3、relate to the work on this standard: Committee reference CPL/113 Draft for comment 93/205223 DC ISBN 0 580 25490 9 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee CPL/113, Flow measurement of surface and ground water, upo
4、n which the following bodies were represented: Clyde River Purification Board Department of the Environment Institute of Measurement and Control Institution of Water and Environmental Management National Rivers Authority Water Services Association of England and Wales The following bodies were also
5、represented in the drafting of the standard, through subcommittees and panels: Institute of Freshwater Ecology Institute of Hydrology Institution of Civil Engineers University of Newcastle Upon Tyne Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na,
6、Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680-10C:1996 BSI 07-1999i Contents Page Committees responsibleInside front cover Forewordii Introduction1 1Scope1 2References1 3Definitions1 4Sampling procedure1 5Selection of site1 6Selection of sampler1 7Hand-held samplers2 8Lightw
7、eight remotely-operated samplers3 9Remotely-operated samplers requiring handling machinery4 10Subsurface sampling6 11Choice of sampler for muds7 12Determination of sample mass and number of samples7 13Errors8 Annex A (informative) Bibliography28 Figure 1 Pipe scoop sampler with hinged cover9 Figure
8、2 Bag scoop sampler with canvas bag10 Figure 3 Push or hammer corer sampler11 Figure 4 Push or hammer cylinder corer sampler with piston12 Figure 5 Core catcher13 Figure 6 Liquid carbon dioxide freeze-core sampler14 Figure 7 Drag bucket sampler15 Figure 8 Lightweight grab sampler with 90 closure16 F
9、igure 9 Lightweight grab sampler with 180 closure17 Figure 10 Anchor dredge18 Figure 11 Grab sampler with 90 closure19 Figure 12 Heavyweight grab sampler with 180 closure20 Figure 13 Heavyweight grab sampler with 180 closure21 Figure 14 Free fall gravity corer. Circular barrel corer22 Figure 15 Free
10、 fall gravity corer. Square barrel corer23 Figure 16 Frame-guided gravity corer. Circular barrel corer24 Figure 17 Frame-guided gravity corer. Square barrel corer25 Figure 18 Vibrocorer26 Figure 19 Design curves for samples of mass m27 Table 1 Examples of combinations of rpi and pi7 Table 2 Students
11、 t values at the 95 % confidence limit for different numbers of initial bulk samples (x)8 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680-10C:1996 ii BSI 07-1999 Foreword This Part of BS 3680 has b
12、een prepared by Technical Committee CPL/113. It supersedes BS 3680-10C:1980 which is withdrawn. This revision of BS 3680-10C has been prepared in order to bring the techniques and equipment described up to date. The scope has been extended to include cohesive-bed materials, and details of the constr
13、uction and deployment of all the major types of sampler are presented. This standard is one of a series of Parts of BS 3680-10 on sediment transport. The other Parts are as follows. Part 10B: Measurement of suspended sediment; Part 10D: Methods for determination of concentration, particle size distr
14、ibution and relative density of sediment in streams and canals; Part 10E: Sampling and analysis of gravel bed material. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with
15、 a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 28, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had ame
16、ndments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680-10C:1996 BSI 07-19991 Introduction Bed-material samplers are used to obtain samples of sed
17、iment from the bed of a watercourse. They are not to be confused with bed-load discharge samplers which are used to determine the discharge of sediment as bed load. The particle size data derived from bed samples, together with hydraulic data, are necessary for the computation of bed material load a
18、nd for flow estimation. This standard covers methods for sampling both non-cohesive and cohesive bed material. Sediment composed of material with a particle size finer than 30 4m is cohesive. However, coarser material can also be cohesive if it contains a small proportion of this finer fraction. 1 S
19、cope This Part of BS 3680 gives guidance on methods for sampling of both non-cohesive sand-bed material and cohesive-bed material (both of which may contain some fine gravel) principally for the purpose of determining the grain size frequency distribution of the bed material in open channels. NOTEOt
20、her publications of relevance to samplers and sampling techniques are listed in the bibliography in Annex A. 2 References 2.1 Normative references This Part of BS 3680 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropri
21、ate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this British Standard only when incorporated in the reference by amendment or revis
22、ion. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative references This Part of BS 3680 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this stand
23、ard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Part of BS 3680, the definitions given in BS 3680-1:1991 apply, together with the following. 3.1 sand sediment having a particle diameter between 0.0625 mm and 2 mm 4
24、Sampling procedure Ideally, the size composition of the bed material should be determined for various stages of flow, as composition can change due to scour and fill activities. In cases where information is required on the composition of layers located more than approximately 0.05 m below the surfa
25、ce of the bed, the use of core-type samplers is recommended. Precautions should be taken to prevent fine particles escaping from the sample. 5 Selection of site The site for sampling bed material for the purpose of computing bed material load or for flow estimation should be located as near as possi
26、ble to the site where hydraulic measurements are made or need to be estimated. Equations for estimating bed load transport and flow resistance usually need measurements from a straight uniform section of channel. Site conditions should be selected that are suitable for the estimating equations which
27、 are to be used. When estimates of total load are to be made, it is also essential that the site conforms to the conditions specified for the measurements of suspended sediment loads in BS 3680-10B. For investigations of bed material transport rates it is recommended that as a minimum a sample shoul
28、d be taken at each vertical in the cross-section where sediment transport is to be measured. 6 Selection of sampler In order to sample successfully, the sampler and the sampling method need to be chosen for their suitability for the particular circumstances. Results obtained using different methods
29、may not necessarily be comparable. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680-10C:1996 2 BSI 07-1999 When bed material is sampled, the sample inevitably suffers some form of disturbance. This can result in loss of fines, in whic
30、h case the sample is referred to as “disturbed”, or in loss of fabric, which is referred to as “structural disturbance”. Structural disturbance of the sample does not affect the assessment of the erodability of non-cohesive sediments, whereas it does affect the results of tests on the erodability of
31、 cohesive sediments. The construction and use of different types of samplers are described in clauses 7, 8 and 9. 7 Hand-held samplers 7.1 General Hand-held samplers are lightweight devices which can be operated by an individual while wading or, in deeper water, by a Scuba diver. Hand-held samplers
32、include bed surface samplers and core samplers. 7.2 Bed surface samplers 7.2.1 Sampling cylinders 7.2.1.1 Construction A sampling cylinder comprises a metal cylinder which encloses the area of bed to be sampled, and which is heavy enough to resist the flow. If practicable, the cylinder should break
33、the water surface. 7.2.1.2 Deployment Digging tools are used to remove samples from within the enclosed volume. The cylinder helps to minimize the washout of fines. 7.2.1.3 Sample type This method yields disturbed samples. The top 0.1 m approximately of the bed is sampled. 7.2.2 Pipe scoops 7.2.2.1
34、Construction A pipe scoop comprises a pipe, one end of which is closed and the other end of which is bevelled to form a cutting edge, attached to a wading rod. A hinged cover plate, held closed by a spring, is mounted over the open end. The plate is opened by a rope (see Figure 1). 7.2.2.2 Deploymen
35、t The pipe is pushed along the bed into the current. The plate is opened to sample then immediately closed, thus minimizing washout. 7.2.2.3 Sample type This method yields disturbed samples. Samples of mass up to 3 kg can be obtained. The top 0.05 m approximately of the bed is sampled. 7.2.3 Bag sco
36、ops 7.2.3.1 Construction A bag scoop comprises a metal ring with an attached flexible bag, mounted on a wading rod (see Figure 2). 7.2.3.2 Deployment The ring is forced into the bed and dragged upstream until the bag is full see Figure 2 a). As the sampler is raised the bag seals automatically see F
37、igure 2 b). 7.2.3.3 Sample type This method yields disturbed samples. Samples of mass up to 3 kg can be obtained. The top 0.05 m approximately of the bed is sampled. 7.3 Core samplers 7.3.1 Push or hammer corers and boxes 7.3.1.1 Construction These include metal or plastics corers up to 150 mm in di
38、ameter and boxes of up to 0.25 in side. 7.3.1.2 Deployment The cylinder or box of the corer is pushed or hammered into the bed and dug or pulled out. Sample retention can be ensured by use of one or more of the following methods. a) A plate is slid beneath the corer and the cylinder or box is dug ou
39、t. b) A partial vacuum can be created above the sample. 1) After the insertion of the cylinder or box, the water-filled space above the sample can be sealed off by means of a screw cap, thus forming a partial vacuum when the sampler is withdrawn (see Figure 3). 2) Alternatively, in the case of cylin
40、der samplers, the cylinder can be fitted with a piston which rises on the surface of the sample and is locked when the sampler has been pushed or hammered to the desired depth. A partial vacuum develops below the piston and helps to hold the sample in the cylinder as it is withdrawn from the bed (se
41、e Figure 4). c) In the case of cylinder samplers a core catcher (sphincter) of flexible stainless steel petals can be located at the bottom opening of the cylinder (see Figure 5). 7.3.1.3 Sample type This method disturbs the texture and structure of the sample, although the gross particle population
42、 may be preserved. Maximum penetration is approximately 0.5 m. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 03:54:00 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3680-10C:1996 BSI 07-19993 7.3.2 Freeze-core samplers 7.3.2.1 Construction A freeze-core sampler comprises a thin walled copper
43、 or mild steel tube with a hardened steel tip. A probe, through which liquid carbon dioxide, liquid nitrogen or solid carbon dioxide mixed with acetone can be injected, is inserted into the tube. In the case of liquid carbon dioxide, delivery is from a pressurized cylinder via fine nozzles in the pr
44、obe (see Figure 6). 7.3.2.2 Deployment The outer tube is hammered into the bed and the probe, connected to the coolant, inserted into it. After a suitable period, which depends on the sediment properties and the ambient temperature, the tube is pulled out of the bed with the adjacent sediment frozen
45、 to it. 7.3.2.3 Sample type This method yields a spindle-shaped frozen “core”up to 0.5 m in length and with a maximum diameter of approximately 0.3 m. Sedimentary structures are disturbed but recognizable. 7.3.2.4 Limitations The method is not suitable for Scuba use or for water depths in excess of
46、3.5 m. 8 Lightweight remotely-operated samplers 8.1 General These samplers can be hand-operated and can be deployed from small boats. They include bed surface samplers and core samplers. 8.2 Bed surface samplers 8.2.1 Pipe scoops and bag scoops 8.2.1.1 Construction Pipe scoops and bag scoops are con
47、structed as described in 7.2.2.1 and 7.2.3.1, respectively. The scoop is attached to a pole up to 4 m in length. 8.2.1.2 Deployment The scoops are deployed as described in 7.2.2.2 and 7.2.3.2, respectively. Normally it is necessary for the boat to be anchored. 8.2.1.3 Sample type This method yields
48、disturbed samples. Samples of mass up to 3 kg can be obtained. The top 0.05 m approximately of the bed is sampled. 8.2.1.4 Limitations Use of this method is limited to water depths of less than 4 m and velocities of less than 1.0 ms1. 8.2.2 Drag buckets NOTEThese are also known as dredges. 8.2.2.1 C
49、onstruction The sampler comprises a weighted bucket or cylinder with a flared cutting edge at one end and a sample collecting receptacle at the other. A drag rope is attached to a pivoting bridle towards the cutting end of the cylinder (see Figure 7). 8.2.2.2 Deployment The device is lowered to the bed and dragged along it from a boat moving slowly into the current. To ensure contact of the cutting edge with the bed a streamlined weight can be attached to the rope. 8.2.2.3 Sample type This method yields disturbed sampl
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