A Study of Methods Used in MEASUREYENT AND ANALYSIS

[Pages:205]A Study of Methods Used i n MEASUREYENT AND ANALYSIS OF SEDIMENT LOADS I N STREAMS

Planned and conducted j o i n t l y by Tennessee Valley Authority, Corps of Engineers,

Department of Agriculture, Geological Survey, Bureau of Reclamation, Indian Service, and Ioura I n s t i t u t e of Xydraulic Research

Report No. 4 METHOES OF ANALYZLNG SEDIMENT SAMPLES

Published a t S t . Pau.1 U . S . Engineer D i s t r i c t S u b - o f f i c e

Hydraulic Laboratory, University of Iowa Iowa C i t y , Iowa

November 1 9 4 1

The c o o p e r a t i v e s t u d y of methods used i n MEASUREMENT AND ANALYSIS OF SEDIMENT LOADS I N STliEAMS covers phases i n d i c a t e d by t h e following r e p o r t t i t l e s .

Report No. 1 FIELD PRACTICE AND EQUIPMENT USED I N SAMPLING SUSPENDED SEDIMENT

Report No. 2 EQUIPMENT USED FOR SAMPLING BED-LOAD AND BED MATERIAL

Report No. 3 ANALYTICAL STUDY OF METHODS OF SAMPLING SUSPENDED SEDIMENT

Report No. 4 METHODS OF ANALYZING SEDIMENT SAMPLES

Report No. 5 LABORATORY INVESTIGATIONS OF SUSPENDED SEDIMENT SAMPLERS

Synopsis

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SYNOPSE

A description and discussion of methods of determining particle size, particularly with reference to their adaption tc suspended sediment

samples, occupir2s the major portion of this report. The size determination of fine-grained materials, i.e., particles

smaller than about 1/16 mm., is based almost entirely upon fall velocities in a fluid, the relation of fall velocities and fluid properties being interpreted in terms of particle diameters by Stokes1 law. Convenient graphical methods for calculating particle diameters from the observed fall velocities and fluid properties are presented for conditions where Stokes' law does and does not apply. The review reveals that the greater number of the present methods are not sufficiently sensitive and accurate for analyzing suspended sediment samples of very low concentrations. The need for development of rapid, accurate, and reliable methods adaptable to mass analysis of suspended sediment samples is apparent.

Although sieving has been the common method for analyzing coarse sediments, a number of hydraulic separation methods have been devised that appear promising. Further developmentof these settling rate methods is needed in this country, for, as emphasized in the report, a diameter calculated from a fall velocity is generally more valuable in sediment studies than a sieve diameter or a direct physical measurement.

The methods of analyzing sediment samples for total solids concentration are also described and discussed; first, as separate independent procedures and then in relation to size analysis methods. Several relatively new methods, advantageous to use with certain types of sediment samples, are presented.

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Synopsis

Procedures for a number of the more common methods of particle size a.nd total concentration analysis, as used by various agencies, are described in detail in the appendix. Applicable standard procedures of the American Society for Testing Materials are indicated.

h extensive bibliography is given, classified by subjects as well a s by authors, in alphabetical order.

Table of Contents

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Section

TABLE OF CONTENTS

I. INTRODUCTION

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Purposeofreport . . . . . . . . . . . .

. . . . Purpose

Authori

and sc ty and

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11 12 12

11. NATURE OF PROBLEM

. Character of . . Character of

Grade s c a l e s

. . Organization

samples . . . part,i cles . .

and expressi of m a t e r i a l

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o.f .p a. r t.i c.l e.

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16 18 21

PART ONE

FALL OF PARTICLES I N FLUIDS

PARTICLE SIZE ANALYSIS

. . .. .. . .. . . . . . . . . . Application of f a l l v e l o c i t i e s t o s i z e a n a l y s i s

Nhture of p a r t i c l e movement

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23 24

F a c t o r s a f f e c t i n g p a r t i c l e fall and d e f i n i t i o n s of p a r t i c l e s i z e . 25

I V . FALL OF PARTICLES W I T H I N THE RANGE OF STOKES1 LAW

. . . . . . . . . . . . . DevelopmentofStokest law

.

. . . . . . . S i m p l i f i e d forms and g r a p h i c a l s o l u t i o n s

. . . . . . . . . . . Assumptions and t h e i r s i g n i f i c a n c e

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29 30 33

V . FALL OF PARTICLES OUTSIDE THE ~ C OFESTOKESt LAW

. . . . . . . . . . . . . . Relation t o t h e Reynolds number

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38

. . . . . Heywood's g r a p h i c a l s o l u t i o n c o n s i d e r i n g p a r t i c l e shape

42

V I . SUMMARY OF PART ONE

16 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

PART TWO METHODS OF PARTICLE SIZE ANALYSIS FOR FINE-GRAINED SEDIMENTS

V I I . STATEMrnJT OF PROBLEM

17 18

Coarse and Outline of

. . . f i n e sediments

methods

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48 49

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Table of Contents

'Section

. VIII PRESENTATION OF METHODS

. . . . . . . . Microscopic . . . . . . . . Decantation

. . . . Elutriation methods . . Elutriation with water

. . . Elutriation with air

Accumulative sedimentation

. Fractional sedimentation

. . . . . . . . . . Pipette

. . . . . . . . Hydrometer

. . . . . . . . . . Plummet

Manometer

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. . . . . . . . . . Centrifugal methods

Optical methods

. . . . . . . Miscellaneous

.IX SUMMARY OF PART TWO

33 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

PART THREE IvIETHODS OF PARTICLE SIZE ANALYSIS FOR COASSE-G-RAINED SEDIMENTS

.X DIRECT MEASUREPlENT

34 35

General . . . .

Direct methods

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131 131

SIEVE ANALYSIS

36 37 5 3

Standard sieves

. . . Technique . . . Accuracy

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133 133 135

. XI1 METHODS BASED ON SETTLING RATES

39 40 41 42 43

. Adaptability to coarse material . . . . Optical lever siltometer . . . . . . . . . . . Siltometer . . Accumulative sedimentation tubes

Fractional sedimentation tube

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138 138 140 143 146

. XI11 SUMMARY OF PART THREE

Table of Contents

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Section

PART FOUR METHOD OF DETEHMINING TOTAL CONCENTRATION

. XIV GENERAL

45 46 47 48

Influence of type of

. Units of measurement

Dissolves material Manner of p r e s e n t a t i o

. . sample na.nd.. m..e..tho..ds..

. o..f

. ..c

. a..l

.. c..u l..a

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. o..n

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151 152 153 155

. XV BASIC METHODS OF DETEMINING TOTAL CONCENTRATION

49 50 51 52 53 54 55

. . . . Sedimentation. decant

Filterpaper Gooch and alundum c r u

. . . F i l t e r candles . C e n t r i f u g a l method . . O p t i c a l methods

Displacementmethod

a.t i.o n.. .c...i b....l e....s

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o......n

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157 158 159 162 163 165 166

. X V I RELATION OF BASIC METHODS TO METHODS OF SIZE ANALYSIS

. . . . . . . . . . . . . . . . . 56 Methods whereby individual s i z e f r a c t i o n s are obtained

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. . . . Methods whereby sediment

I n d i r e c t methods

.um. u.l .ates.

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168 169

. X V I I SUMMARY OF PART FOUR

59 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

APPENDIX A .DETAILED SIZE ANALYSIS PROCEDURES

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61 62 63

. S i e v i n g . D e c a n t a t i o n

Pipette

Hydrometer

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175 177 179 182

APPENDIX B .DETAILED TOTAL CONCENTUTION ANALYSIS METHODS

64 65 66

. Gooch c r u c i b l e . . Alundum c r u c i b l e

Filterpzper

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185 186 187

BIBLIOGRAPHY BY AUTHOR . . . . . . . . . . . . . . . . . . . . . . 189

. . . . . . . . . . . . SUPPLEMENTARY BIBLIOGRAPHY ON SIZE ANALYSIS

199

REFERENCES CLASSIFIED BY SUBJECT . . . . . . . . . . . . . . . . . 202

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