BS 3680-10E:1993

Committees responsible
National foreword
Introduction
Method
1. Scope
2. Normative references
3. Definitions
4. Sampling equipment and procedures
5. Assignment of grain sizes
6. Frequency
7. Grain size/frequency distributions
8. Selection of sampling procedure
9. Determination of sample size
10. Errors
Tables
1. Weighting factors for conversion of sampling
     procedures
2. Student's t values at 95% confidence level for
     various initial sample sizes
Figures
1. Pipe sampler
2. Gravel-cutter sampler
3. Sampling site selection hierarchy

Specifies methods for sampling surface and subsurface gravel-bed material and the procedures to determine the size distribution of gravel-bed material in open channels.

1.1 This International Standard specifies methods for sampling surface and subsurface gravel-bed material and the analytical procedures to determine the size distribution of gravel-bed material in open channels.

1.2 This International Standard applies to material having diameters of 2 mm and over.

1.3 In practice, gravel-bed material may consist of two components: a coarser layer on the surface and finer subsurface material. Surface material is particularly relevant to investigations of the initiation of bed material movement and flow resistance, while subsurface material is mainly relevant to investigations of bed material transport. This International Standard does not attempt to correlate these two distinct populations.

1.4 There are two sampling techniques applicable to graded gravel-bed material. One method is to collect a definable in situ volume of material which is subsequently dealt with as a bulk sample. The second method is to sample material from the surface using one of several procedures. These two methods are discussed separately in this International Standard, and conversion factors are presented which are derived from idealized homogeneous material.