1、BRITISH STANDARD BS3680-10C: 1996 Measurement of liquid flow in open channels Part10: Sediment transport Part10 C: Guide to methods of sampling of sand-bed and cohesive-bed materialsBS3680-10C:1996 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board,
2、was published underthe authority of the Standards Board and comes intoeffect on 15 July1996 BSI 07-1999 First published March1980 Second edition July1996 The following BSI references relate to the work on this standard: Committee reference CPL/113 Draft for comment93/205223 DC ISBN 0 580 25490 9 Com
3、mittees 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, upon which the following bodies were represented: Clyde River Purification Board Department of the Environment Institute
4、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 represented in the drafting of the standard, through subcommittees and panels: Institute of Freshwater Ecology Institu
5、te of Hydrology Institution of Civil Engineers University of Newcastle Upon Tyne Amendments issued since publication Amd. No. Date CommentsBS3680-10C:1996 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 References 1 3 Definitions 1 4 Sampl
6、ing procedure 1 5 Selection of site 1 6 Selection of sampler 1 7 Hand-held samplers 2 8 Lightweight remotely-operated samplers 3 9 Remotely-operated samplers requiring handling machinery 4 10 Subsurface sampling 6 11 Choice of sampler for muds 7 12 Determination of sample mass and number of samples
7、7 13 Errors 8 Annex A (informative) Bibliography 28 Figure 1 Pipe scoop sampler with hinged cover 9 Figure 2 Bag scoop sampler with canvas bag 10 Figure 3 Push or hammer corer sampler 11 Figure 4 Push or hammer cylinder corer sampler with piston 12 Figure 5 Core catcher 13 Figure 6 Liquid carbon dio
8、xide freeze-core sampler 14 Figure 7 Drag bucket sampler 15 Figure 8 Lightweight grab sampler with90 closure 16 Figure 9 Lightweight grab sampler with180 closure 17 Figure 10 Anchor dredge 18 Figure 11 Grab sampler with90 closure 19 Figure 12 Heavyweight grab sampler with180 closure 20 Figure 13 Hea
9、vyweight grab sampler with180 closure 21 Figure 14 Free fall gravity corer. Circular barrel corer 22 Figure 15 Free fall gravity corer. Square barrel corer 23 Figure 16 Frame-guided gravity corer. Circular barrel corer 24 Figure 17 Frame-guided gravity corer. Square barrel corer 25 Figure 18 Vibroco
10、rer 26 Figure 19 Design curves for samples of mass m 27 Table 1 Examples of combinations of r piand pi 7 Table 2 Students t values at the95% confidence limit for different numbers of initial bulk samples (x) 8 List of references Inside back coverBS3680-10C:1996 ii BSI 07-1999 Foreword This Part of B
11、S3680 has been prepared by Technical Committee CPL/113. It supersedes BS3680-10C:1980 which is withdrawn. This revision of BS3680-10C 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 t
12、he construction and deployment of all the major types of sampler are presented. This standard is one of a series of Parts of BS3680-10 on sediment transport. The other Parts are as follows. Part 10B: Measurement of suspended sediment; Part 10D: Methods for determination of concentration, particle si
13、ze distribution 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. Complia
14、nce with 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, pagesi andii, pages1 to28, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had
15、 amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS3680-10C:1996 BSI 07-1999 1 Introduction Bed-material samplers are used to obtain samples of sediment from the bed of a watercourse. They are not to be confused with bed-load discharge samplers which
16、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 and for flow estimation. This standard covers methods for sampling both non-cohesive and cohesive bed mat
17、erial. Sediment composed of material with a particle size finer than304m is cohesive. However, coarser material can also be cohesive if it contains a small proportion of this finer fraction. 1 Scope This Part of BS3680 gives guidance on methods for sampling of both non-cohesive sand-bed material and
18、 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. NOTEOther publications of relevance to samplers and sampling techniques are listed in the bibliography in Annex A
19、. 2 References 2.1 Normative references This Part of BS3680 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references,
20、 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 revision. For undated references, the latest edition of the cited publication applies, together with any amendmen
21、ts. 2.2 Informative references This Part of BS3680 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions F
22、or the purposes of this Part of BS3680, the definitions given in BS3680-1:1991 apply, together with the following. 3.1 sand sediment having a particle diameter between0.0625mm and2mm 4 Sampling procedure Ideally, the size composition of the bed material should be determined for various stages of flo
23、w, as composition can change due to scour and fill activities. In cases where information is required on the composition of layers located more than approximately0.05m below the surface of the bed, the use of core-type samplers is recommended. Precautions should be taken to prevent fine particles es
24、caping 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 possible to the site where hydraulic measurements are made or need to be estimated. Equations for estimating bed load tran
25、sport 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 are to be used. When estimates of total load are to be made, it is also essential that the site conforms to the cond
26、itions specified for the measurements of suspended sediment loads in BS3680-10B. For investigations of bed material transport rates it is recommended that as a minimum a sample should be taken at each vertical in the cross-section where sediment transport is to be measured. 6 Selection of sampler In
27、 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 may not necessarily be comparable.BS3680-10C:1996 2 BSI 07-1999 When bed material is sampled, the sample inevitably su
28、ffers some form of disturbance. This can result in loss of fines, in which 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 sed
29、iments, whereas it does affect the results of tests on the erodability of cohesive sediments. The construction and use of different types of samplers are described in clauses7, 8 and9. 7 Hand-held samplers 7.1 General Hand-held samplers are lightweight devices which can be operated by an individual
30、while wading or, in deeper water, by a Scuba diver. Hand-held samplers 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 heav
31、y enough to resist the flow. If practicable, the cylinder should break 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 to
32、p0.1m approximately of the bed is sampled. 7.2.2 Pipe scoops 7.2.2.1 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
33、 end. The plate is opened by a rope (see Figure 1). 7.2.2.2 Deployment 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 to3kg can be obtained
34、. The top0.05m approximately of the bed is sampled. 7.2.3 Bag scoops 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
35、 2 a). As the sampler is raised the bag seals automatically see Figure 2 b). 7.2.3.3 Sample type This method yields disturbed samples. Samples of mass up to3kg can be obtained. The top0.05m approximately of the bed is sampled. 7.3 Core samplers 7.3.1 Push or hammer corers and boxes 7.3.1.1 Construct
36、ion These include metal or plastics corers up to150mm in diameter and boxes of up to0.25 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 i
37、s slid beneath the corer and the cylinder or box is dug out. 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 withdr
38、awn (see Figure 3). 2) Alternatively, in the case of cylinder 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
39、sample in the cylinder as it is withdrawn from the bed (see 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 (seeFigure 5). 7.3.1.3 Sample type This method disturbs the texture and struct
40、ure of the sample, although the gross particle population may be preserved. Maximum penetration is approximately0.5m.BS3680-10C:1996 BSI 07-1999 3 7.3.2 Freeze-core samplers 7.3.2.1 Construction A freeze-core sampler comprises a thin walled copper or mild steel tube with a hardened steel tip. A prob
41、e, 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 probe (see Figure 6). 7.3.2.2 Deployment The outer tube
42、 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 to it. 7.3.2.3 Sample type This method yields a spin
43、dle-shaped frozen “core”up to0.5m in length and with a maximum diameter of approximately0.3m. 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 of3.5m. 8 Lightweight remotely-operated samplers 8.1 General
44、 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 constructed as described in7.2.2.1 and7.2.3.1, respectively. T
45、he scoop is attached to a pole up to4m in length. 8.2.1.2 Deployment The scoops are deployed as described in7.2.2.2 and7.2.3.2, respectively. Normally it is necessary for the boat to be anchored. 8.2.1.3 Sample type This method yields disturbed samples. Samples of mass up to3kg can be obtained. The
46、top0.05m approximately of the bed is sampled. 8.2.1.4 Limitations Use of this method is limited to water depths of less than4m and velocities of less than1.0ms 1 . 8.2.2 Drag buckets NOTEThese are also known as dredges. 8.2.2.1 Construction The sampler comprises a weighted bucket or cylinder with a
47、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
48、 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 samples. Samples of mass up to1kg can be obtained. The top0.05m approximately of the bed is sampled. 8.2.2.4 Limitations Samples are liable to be affect
49、ed by washing-out of material. 8.2.3 Grab samplers with90 closure 8.2.3.1 Construction Two quarter-cylinder shaped buckets are hinged to each other, forming a half-cylinder when closed. Arms are attached to each bucket to which a rope and pulley system is fastened. A latching system holds the buckets open until the grab reaches the bed. The slackening of the rope releases the latch, and the tightening of the rope as the grab is retrieved closes the buckets (see Figure 8). 8.2.3.2 Deployment The grab is latched open an
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