E-2510

R.M.HARDY & ASSOCIATES LTD.

GEOTECHNICAL INVESTIGATION

PROPOSED BRIDGE SITE..

FRANCIS CREEK: I

MILE 617.9 , .,

R.M.HARDY & ASSOCIATES LTD. CONSULTING ENGINEERING & TESTING . GEOTECHNICAL DIVISION

File No. E 2 5 1 0

October 1 6 , 1973

M r . F. E. Kimball, P.Eng. , Manager of Northern Roads Program, Department of P u b l i c Works of Canada, One Thornton Court, Edmonton, Alber ta .

Re : Geo techn ica l Inves t iga t ions Mackenzie Highway Proposed Bridge S i te , F ranc i s Creek Mile 617 .9

Dear M r . Kimball:

W e are p l e a s e d t o s u b m i t a r e p o r t on our g e o t e c h n i c a l i n v e s t i g a t i o n s a t t h e s i te of t h e proposed b r idge ac ross F ranc i s Creek.

Should you wish for any explana t ion or a m p l i f i c a t i o n o f a n y p a r t of t h i s r e p o r t w e w i l l be p leased t o be a t y o u r s e r v i c e .

Respec t fu l ly submi t ted ,

R. M. HARDY & ASSOCIATES LTD.,

GM/ j c

1 0 2 1 4 - 1 1 2 S T R E E T , E D M O N T O N , A L B E R T A T 5 K 1 M 5 P H O N E ( 4 0 3 ) 4 2 6 - 0 4 0 5 CONSOLIDATING THE SERVICES OF: R. M. HARDY & ASSOCIATES LTD., MATERIALS TESTING LABORATORIES LTD. a NON DESTRUCTIVE INSPECTION LTD.

BURNABY CALGARY DAWSON CREEK EDMONTON LETHBRIDGE PRINCE GEORGE RED DEER WINNIPEG

R.M.HARDY & ASSOCIATES LTD.

INTRODUCTION

A t t h e r e q u e s t of M r . F. E. Kimball, P.Eng.,

Manager of Northern Roads Program, Department of P u b l i c

Works of Canada, Western Region, R. M. Hardy & Associates

Ltd. undertook a g e o t e c h n i c a l i n v e s t i g a t i o n a l o n g p a r t

o f the p roposed loca t ion of t h e Mackenzie Highway.

T h i s r e p o r t d e a l s o n l y w i t h t h a t p a r t o f t h e i n v e s t i g a t i o n

appe r t a in ing t o t he p roposed b r idge a t Franc is Creek .

The l o c a t i o n of t h i s b r i d g e s i te i s shown

on mosa ic shee t No. 50 of a s e t of mosaics prepared

by the Department of P u b l i c Works f o r t h e Mackenzie

Highway work. The s i te is covered by a e r i a l p h o t o g r a p h s

no. A22773-155, 156 and 157 (scale 1" = 1 0 0 0 ' ) . The

c r o s s i n g i s located about one mile upstream from the

mouth of Francis Creek where it e n t e r s the Mackenzie

River and approximately 350 feet upstream from where

t h e CNT t e l e p h o n e l i n e crosses the c r eek .

I n a d d i t i o n t o m o s a i c s , a c e n t e r l i n e p r o f i l e

and aer ia l photographs R. M. Hardy & Associates Ltd.

was provided with a ske tch p lan and prof i le showing

t h e proposed crossing by the Department. This l a s t

drawing i s en t i t l ed "P roposed Dra inage S t ruc tu re a t

F ranc i s Creek , S t a t i o n 1896+60", and was used as t h e

b a s i s f o r P l a t e 1, Appendix A.

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R.M.HARDY & ASSOCIATES LTD.

A r e p o r t e n t i t l e d " G e o t e c h n i c a l I n v e s t i g a t i o n ,

Mackenzie Highway, Mile 5 4 4 t o Mile 635" has been p rev ious ly

submi t ted t o the Department. The g e o t e c h n i c a l c o n d i t i o n s

are d i s c u s s e d i n Volume I w h i l e V o l u m e II c o n t a i n s

information on permafrost of a more g e n e r a l n a t u r e .

W e recommend that these volumes be read in conjunct ion

wi th t h i s r e p o r t .

DRILLING AND TESTING

Four tes t h o l e s were d r i l l e d a d j a c e n t t o

t h e creek on March 1 2 , 1973 , u s ing a F a i l i n g 1 0 0 0 drill

r i g . Compressed a i r w a s used as t h e d r i l l i n g f l u i d .

Disturbed samples were ob ta ined a t t w o foot i n t e r v a l s

f o r moi s tu re con ten t de t e rmina t ions , ice d e s c r i p t i o n s

and material i d e n t i f i c a t i o n .

A l l samples were t e s t e d i n t h e f i e l d l a b o r a t o r y

which formed p a r t of t h e mobile camp accompanying the

o p e r a t i o n . Logs of t h e tes t h o l e s a r e i n c l u d e d i n

Appendix A.

TOPOGRAPHY

The g e n e r a l d i r e c t i o n of t h e d r a i n a g e i n

t h e area i s souther ly towards t h e Mackenzie River.

However, a long t h e c e n t e r l i n e of t h e proposed highway

the g round rises g r a d u a l l y i n a w e s t e r l y d i r e c t i o n

a t an average g rad ien t of 30 f e e t i n t h e m i l e .

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R.M.HARDY & ASSOCIATES LTD.

The banks of Francis Creek are r e l a t i v e l y

l o w w i t h t h e s t e e p e s t v a l l e y wall being found on the

no r th s ide where t he rise i n ground e leva t ion i s 1 0

f e e t i n a d i s t a n c e of 25 f e e t . On the south bank the

r ise is only 4 feet i n a h o r i z o n t a l d i s t a n c e o f 1 2 0

f e e t . The wid th o f the c reek a t t h e water l i n e i s

approximately 50 f e e t .

SOIL PROFILE

The soils i n t h e area c o n s i s t of c l a y , s i l t ,

sand and gravel which are in te rbedded . Gravel and

sand predominate the c reeks . Water c o n t e n t s are h igh ly

va r i ab le w i th ve ry h igh water c o n t e n t s f o u n d i n t h e

soils n e a r t h e s u r f a c e .

The t w o t es t h o l e s on the south approach

showed s i l t and sand over ly ing grave l a t Test Hole

9 2 0 and sand overlying gravel a t T e s t Hole 921 .

On the no r th app roach , T e s t Holes 9 2 2 and

923 showed sand , g rave l , c lay and grave l a t T e s t Hole

9 2 2 and grave l over ly ing sand a t T e s t Hole 923.

The maximum water c o n t e n t e n c o u n t e r e d i n

any of the four tes t h o l e s w a s 2 2 p e r c e n t which was

found i n Test Hole 9 2 2 a t dep ths of 4 and 14 f e e t .

The water c o n t e n t s are g e n e r a l l y l o w .

Only small amounts of v i s i b l e ice were noted

in the samples . Unfrozen ground w a s e n c o u n t e r e d i n

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R.M.HARDY & ASSOCIATES LTD.

Test Hole 9 2 2 a t a depth o f 1 7 feet which i s approximately

7 f ee t be low the water level o f t h e c r e e k a t a h o r i z o n t a l

d i s t a n c e o f 9 0 fee t f rom the nea res t bank . In a l l

t h e o t h e r t e s t holes, t h e e n t i r e p r o f i l e w a s found

t o be f rozen .

The g r a v e l d e p o s i t s are s a n d y , s i l t y a n d

genera l ly have l o w water c o n t e n t s . NO cobbles o r bou lde r s

were e n c o u n t e r e d d u r i n g d r i l l i n g . The DPW survey crew,

which ca r r i ed ou t a su rvey du r ing t he summer of 1973,

r e p o r t s t h a t t h e stream bed cons i s t s o f rock and g rave l .

D I S C U S S I O N AND RECOMMENDATIONS

The e f f e c t o f a stream on t he pe rmaf ros t

p r o f i l e i s shown on Plate 2 , Appendix A. T h i s c h a r t

shows t h a t t h e thaw bulb beneath even a small c reek

c a n p e n e t r a t e t o c o n s i d e r a b l e d e p t h s a n d t h a t , f o r

b r idge bu i ld ing pu rposes , t he p re sence o f pe rmaf ros t

benea th t he stream bed can be ignored. However, it

should be n o t e d t h a t t h e p e r m a f r o s t p r o f i l e b e n e a t h

t h e s i d e s o f a stream plunges a t an ex t r eme ly s t eep

angle . I n t h i s case, t h e o u t l i n e o f t h e p e r m a f r o s t

p r o f i l e w i l l be complicated by the gravel which l i es

as an e l eva t ion be low the c r eek . A s t h i s g r a v e l i s

highly permeable , w e would e x p e c t t h a t t h e waters permeating

through it w i l l have thawed the permafrost for a c o n s i d e r a b l e

d i s t a n c e e i t h e r s i d e o f t h e c r e e k . However, w i thou t

a n e x h a u s t i v e d r i l l i n g i n v e s t i g a t i o n it w i l l be imposs ib le

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R.M.HARDY & ASSOCIATES LTD.

t o d e l i n e a t e t h e p e r m a f r o s t p r o f i l e w i t h any degree

of accuracy.

A s i s w e l l known, the f low of water i n n o r t h e r n

creeks var ies t remendously throughout the year . Very

large f lows can be expe r i enced du r ing t he sp r ing runof f .

The bed of t h i s stream s h o u l d b e h i g h l y r e s i s t a n t t o

scour due t o the rock and gravel material i n t h e b e d .

However, t h e amount o f s cour t ha t shou ld be expec ted

w i l l depend on t h e f l o w of water d u r i n g t h e h e i g h t

of spr ing runoff and the cons t r ic t ion imposed on t h e

stream by t h e b r i d g e s t r u c t u r e .

Because o f d i f f i cu l t i e s due t o l o g i s t i c s

it would b e h i g h l y d e s i r a b l e t h a t o n - s i t e work be kept

t o a minimum. For th i s r ea son , t he fo rming of r e in fo rced

concrete abutments or p i e r s shou ld avo ided . Also,

b e c a u s e o f t h e d i f f i c u l t y i n p r e d i c t i n g d e p t h s o f s c o u r ,

it w o u l d b e e x t r e m e l y d i f f i c u l t t o d e s i g n f o o t i n g s

f o r b r i d g e p i e r s and abutments on an economic basis.

The presence o f permafros t would a lmost cer ta in ly l ead

t o d i f f e r e n t i a l v e r t i c a l movements i n b r idge abu tmen t s

founded on the banks a l though, as s t a t ed above , pe rmaf ros t

w i l l no t be a f a c t o r t o b e c o n s i d e r e d f o r s t r u c t u r e s

founded i n t h e stream bed.

We t h e r e f o r e recommend t h a t t h e b r i d g e a b u t m e n t s

and any intermediate piers be supported on dr iven s tee l

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R.M.HARDY & ASSOCIATES LTD.

H p i l e s . I t i s ex t r eme ly un l ike ly t h a t timber p i l e s

could be d r i v e n a t t h i s s i t e wi thout running cons iderable

r i s k o f damage t o t h e timbers. Precast c o n c r e t e p i l e s

shou ld no t be used due t o t h e d i f f i c u l t i e s o f t r a n s p o r t a t i o n

and also b e c a u s e t h e l e n g t h o f p r e c a s t p i l e s w i l l have

t o be de termined in advance . Steel p i p e p i l e s are

n o t recommended as , w i t h timber p i l e s , i t i s u n l i k e l y

t h a t t h e y w i l l b e a b l e t o w i t h s t a n d t h e d r i v i n g stresses.

Steel H p i l e s which are t o be p laced on t h e

banks where they w i l l n o t b e a f f e c t e d by scour should

be d r iven a minimum of 30 f e e t be low ex is t ing g rade and

des igned on the bas i s of a n a l l o w a b l e s k i n f r i c t i o n of

800 p s f (on t he g ros s pe r ime te r ) w i th t he t op 1 0 f e e t

of p i l e b e i n g assumed t o car ry no load .

Steel H p i l e s d r i v e n i n t h e stream bed should

b e d r i v e n a minimum d i s t a n c e o f 2 0 f e e t below the bottom

of a n t i c i p a t e d s c o u r and should be designed on t h e b a s i s

of the "Table o f Pene t ra t ion Res is tance" fo l lowing . Des ign

parameters are summarized on P la te 3 , Appendix A.

Driving steel H p i l e s w i l l r e q u i r e c o n s i d e r a b l e

energy. The w e i g h t o f t h e p i l e d r i v i n g hammer should

b e a t least twice t h e w e i g h t o f t h e p i l e b e i n g d r i v e n .

I f a d i e s e l hammer i s used , the weight o f the hammer

should be a t least equa l t o t h e w e i g h t o f t h e p i l e .

T o p reven t damage t o t h e p o i n t s o f t h e p i l e s w e sugges t

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R.M.HARDY & ASSOCIATES LTD.

that they be r e i n f o r c e d w i t h f l a n g e plates f o r a d i s t a n c e

equa l t o 1 . 5 times t h e s i z e of the p i le . A l t e r n a t i v e l y ,

t h e poin t can be r e i n f o r c e d w i t h a d r i v i n g shoe. P i l e s

should be d r i v e n t o p r a c t i c a l r e f u s a l a c c o r d i n g t o

the fo l lowing table of pene t r a t ion r e s i s t ance a s suming

t h a t t h e hammer del ivers an energy of a t least 15000

foot pounds per blow.

Desc r ip t ion

TABLE O F PENETRATION RESISTANCE

Inches Per B l o w

r e f u s a l .00 - .05

pract ical r e f u s a l - 0 5 - . 2 5

high r e s i s t a n c e . 2 5 - .50

medium r e s i s t a n c e .50 - 1 . 2 5

low res is t ance 1 . 2 5 - 1 . 7 5

I n order t o ensu re t h a t r e f u s a l h a s b e e n r e a c h e d , d r i v i n g

should be c o n t i n u e d f o r a t least 1 0 0 blows a f t e r r e f u s a l

i s f i r s t recorded.

Pi les d r i v e n t o r e f u s a l i n t h e stream bed,

as def ined above, may be designed f o r t h e f u l l s t r u c t u r a l

s t r e n g t h o f t h e p i l e s e c t i o n a c t i n g as a column. The

d e s i g n l o a d w i l l depend upon the allowable stresses

of t h e p i l e , t h e column length and the arrangement

of l a te ra l b rac ing . Piles d r i v e n t o p r a c t i c a l r e f u s a l ,

as def ined above, should be des igned f o r two-thirds

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R.M.HARDY & ASSOCIATES LTD.

n

o f t h e v a l u e p e r m i t t e d f o r t h e p i l e a s a s t r u c t u r a l

column. Consideration should be given t o u s i n g b a t t e r e d

p i l e s on t h e o u t s i d e o f t h e p i l e b e n t s i n o r d e r t o

provide increased la te ra l r e s i s t a n c e .

I f a drop hammer i s u s e d i n d r i v i n g t h e p i l e s ,

ca re shou ld be t aken t ha t the e n e r g y d e l i v e r e d t o t h e

p i l e i s n o t g r e a t e r t h a n 5 0 , 0 0 0 foot-pounds per blow

u n l e s s c a l c u l a t i o n s show t h a t t h e p i l e c a n s a f e l y take

higher impact stresses.

One of the problems faced by b r idges i s t h e

p o s s i b i l i t y o f log jams occurring which can cause p a r t i a l

o r c o m p l e t e f a i l u r e o f t h e b r idge . Log jams a r e o n l y

l i k e l y t o occur where trees t r a v e l l i n g down t h e r i v e r

have a g r e a t e r l e n g t h t h a n t h e c l e a r s p a n o f t h e b r i d g e .

We sugges t t ha t t he he igh t o f trees growing adjacent

t o F r a n c i s Creek upstream of the br idge should be checked

and, should it b e o b s e r v e d t h a t t h e r e i s a p o s s i b i l i t y

o f l a rge trees being washed downstream such fact should

be bo rne i n mind by the b r idge des igne r .

I f p i l e s a r e u s e d t o s u p p o r t a v e r t i c a l f a c e

of embankment f i l l t h e l a t e r a l f o r c e a g a i n s t a p i l e

can be computed by assuming t h e b a c k f i l l t o b e a f l u i d

with a dens i ty o f 60 pounds per cubic foot where the

b a c k f i l l i s not compacted.

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R.M.HARDY & ASSOCIATES LTD.

Embankments cons t ruc t ed be low the h ighes t expec ted

f l o o d l e v e l s h o u l d b e p r o t e c t e d w i t h r i p r a p . A s s u i t a b l e

rock may n o t b e a v a i l a b l e , s a n d b a g s f i l l e d w i t h c o n c r e t e

may have t o be used.

Respec t fu l ly submi t t ed ,

GM/ j c

c

c

APPENDIX A

R.M.HARDY & ASSOCIATES LTD.

Sec t ion Charts

T e s t Hole Logs

!!i 0

n

22

,a

3

N

N

a ./f

1

Q

0, "_

"I \

I

(c

+ f

0

BS

y ci

"-e

0

-i 3

0 0 rf

II

* L i m i t of T h a w B u l b

S c a l e : 1" = 10'

W = River Width C.L. = Center L i n e

G. Mc September 14/73 - 0 I

RMHARDV~ ASSOCIATES L m I THAW BULBS BENEATH RIVERS

N O W ? ? WELLS AREA CONSULTING ENGINEERING & TESTING

PLATE 2

+ - 0 m I

P

1 "

Stream 7 I c R

Scour Depth

I

20' t

Cross Perimeter = 4H = H f t. - 1 2 3

-

Piles on dry land t o be designed on t h e b a s i s of an a l l o w a b l e s h a f t f r i c t i o n o v e r e f f e c t i v e l e n g t h of embedment of D-10 w i t h D minimum = 30 f t .

Piles i n stream bel! t o be d r i v e n t o 20+ feet below scour depth and designed on t h e basis o f p e n e t r a t i o n va lues (see t e x t ) .

1

R . M . ~ ~ A S S ~ C ~ A T E S L ~ CONSULTING ENGINEERING 6. TESTING I MACKENZIE HIGHWAY

N O U J WELLS AREA BRIDGE PILES

PLATE 3

W

t t

r I R.M.HARDY AND ASSOCIATES LTD. 1 DRILL HOLE REPORT I DEPARTMENT OF PUBLIC WORKS, CANADA

MACKENZIE HIGHWAY

11

'IELD ENG:'

SOIL DESCRIPTION

DRAINAGE: 4

ICE MSCRIPTION

i ' I GRAIN- !

0 : WATER CONTENT ("/o OF DRY WEIGHT a= ICE CONTENT ('/o OF SAMPLE VOLUME) :z 0

511 r TEST HOLE

MILE B,C,S NUMBEF

REMARKS

I f t I I I I

R.M. HARDY AND ASSOCIATES LTD. DRILL HOLE REPORT DEPARTMENT OF PUBLIC WORK! MACKENZIE HIGHWA' I OFFSET : 'IELD ENG: IDATE DRILLED /.7,'3/74 AIF

SOIL DESCRIPTION

9F ACE DRAINAGE: I

SIZE T

CANADA

TEST HOLE

K++E 6/71 c I922

REMARKS

I t

77 DWNi '3

2

4

6

10

12

14

I6

I6

i! R.M. HARDY AND ASSOCIATES LTD. DRILL HOLE REPORT DEPARTMENT OF PUBLIC WORKS, CANADA

MACKENZIE HIGHWAY NG, IDATE DRILLED: /2/3/3\ AIRPHOTO NO: A 22934- I45 I CHAINAGE: /Sea + 1 OFFSET: TFST H b l F

DRAINAGE :

ICE WSCRIPTION

i I GRAII

L 0 : WATER CONTENT (90 OF DRY WEIGHT) a= ICE CONTENT (O/O OF SAMPLE VOLUME) .I,"

R.M.HARDY & ASSOCIATES LTD.

APPENDIX B

Explanation Sheets

EXPLANATION O F TERMS AND SYMBOLS

USED ON TEST HOLE LOG SHEETS

Depth

This column refers t o t h e depth be low the g round

s u r f a c e i n f e e t .

Sample Number

Tube and core samples were numbered consecut ively

from t h e s u r f a c e . Grab samples were not numbered.

Sample Type

T h i s column i n d i c a t e s t h e d e p t h i n t e r v a l

and condi t ion of each sample a t tempted. Undisturbed

samples i n t h i s program were ob ta ined w i t h Shelby tubes

of 18 inches l ength and 3 i nches diameter, manufactured

from 11 gauge s teel , o r by core d r i l l i n g . Cores were

of 2 .85 inch diameter and up t o 3 6 inches long .

Disturbed samples were obta ined f rom t h e

r e t u r n e d c u t t i n g s .

T i n d i c a t e s t u b e s a m p l e

C i n d i c a t e s core sample

0 i nd ica t e s l a rge g rab s ample

Note: Grab samples taken fo r water c o n t e n t a n d v i s u a l

examination are n o t i n d i c a t e d i n t h i s column.

Percent Recovery

This column shows t h e l e n g t h of sample recovered

as a percentage of t h e length a t tempted . 1 0 0 % recovery i s

no t i nd ica t ed and may be assumed where no value i s shown.

- 1 -

Pene t r a t ion Res i s t ance

No s t a n d a r d p e n e t r a t i o n tests were performed

dur ing t h i s p rog ram.

Soi l Symbol

The s o i l symbols used are e x p l a i n e d i n f u l l

on page 5 of t h i s a p p e n d i x .

S o i l Descr ip t ion

Frozen Ground

The dep th i n t e rva l s ove r wh ich f rozen and un f rozen

ground were encountered are i n d i c a t e d by F and UF r e s p e c t i v e l y .

No a t tempt was made t o d i f f e r e n t i a t e b e t w e e n s e a s o n a l

f ros t and pe rmaf ros t .

Ice Desc r ip t ion

The ice c o n t e n t of pe rmaf ros t soils has been

classified a c c o r d i n g t o t h e Na t iona l Research Counci l

System f o r d e s c r i b i n g p e r m a f r o s t . A b r i e f r e v i e w o f t h e

NRC System i s contained on page 9 of t h i s appendix. Where

no en t ry i s made, t h e type was n o t recorded i n t h e f i e l d .

The amount of ice c o n t a i n e d i n a s o i l sample

w a s e s t i m a t e d i n t h e f i e l d l a b o r a t o r y by i n s p e c t i o n . The

v a l u e a r r i v e d a t by t h e l a b o r a t o r y t e c h n i c i a n h a s b e e n

l e f t unchanged.

- 2 -

Water Content

The n a t u r a l water c o n t e n t of t h e so i l a t t h e

time o f d r i l l i n g i s p l o t t e d a g a i n s t d e p t h o n t h e c h a r t

a t t he r i g h t hand side of t h e l o g . The water c o n t e n t ,

which i s ind ica t ed by a c i rc le , i s expressed as a per -

centage of t h e d r y w e i g h t o f t h e s o i l . I t w i l l be observed

t h a t water c o n t e n t s i n e x c e s s of 1 0 0 % a r e i n d i c a t e d i n

the column a t t h e r i g h t of t h e chart by f i g u r e s .

Volume of Ice

The t o t a l volume of ice in und i s tu rbed s amples

i s i n d i c a t e d on t h e same chart as water c o n t e n t s . The

va lue i s i n d i c a t e d by a t r i a n g l e . T h i s volume is t h e

t o t a l volume of ice i n an undisturbed sample and includes

i n t e r s t i c i a l i ce , a s w e l l as excess ice , and i s expressed

as a percentage of t h e t o t a l volume of t h e sample.

Gra in S ize Analys is

The p r o p o r t i o n s of c l a y , s i l t , sand and gravel

i n a sample are summarized. Grain s i z e c u r v e s f o r e a c h

sample so ana lyzed a r e on s e p a r a t e sheets.

Wet Density

The w e t i n s i t u d e n s i t y of undis turbed samples

i s t h e t o t a l w e i g h t of the sample in pounds ( inc luding ice

and water) d iv ided by t h e volume of t h e sample i n c u b i c feet .

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Dry Densi ty

The d r y i n s i t u d e n s i t y of undis turbed samples

i s the we igh t o f d ry s o i l d iv ided by t he volume of t h e

sample i n c u b i c f e e t .

A t t e r b e r g L i m i t s

The p l a s t i c a n d l i q u i d limits are shown on

t h e water c o n t e n t char t by a h o r i z o n t a l b a r . The Atterberg

system is d i s c u s s e d i n t h e f o l l o w i n g s e c t i o n .

NOTES ON ATTERBERG LIMITS

Soi ls which posses s a s i g n i f i c a n t f r a c t i o n

of c l a y c a n e x i s t i n l i q u i d , p l a s t i c o r so l id states accord ing

to t h e water c o n t e n t . Where t h e water c o n t e n t i s ve ry

h igh , so t h a t t h e s o i l i s i n t h e f o r m of a s l u r r y , t h e

s o i l behaves as a l i q u i d . If t h e water c o n t e n t i s reduced,

f o r example through evaporat ion, t h e c l a y w i l l e n t e r i n t o

a p l a s t i c s t a t e . I f t h e water c o n t e n t i s r educed ye t

f u r t h e r , t h e c l a y w i l l become a s o l i d . The t r a n s i t i o n

from one s ta te t o a n o t h e r o c c u r s g r a d u a l l y o v e r a range

of water c o n t e n t . A t t e r b e r g , a Swedish agronomist, developed

a method fo r d e l i n e a t i n g t h e boundaries between the three

states. If h i s method is u s e d , t h e water content which

marks t h e d i v i d i n g l i n e b e t w e e n t h e p l a s t i c a n d l i q u i d

s t a t e is known as t h e Liquid L i m i t . These w a t e r c o n t e n t s

are a l l expressed as pe rcen tages of the d ry we igh t of

s o i l . The range of water content between t h e p l a s t i c

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MODIFIED UNIFIED CLASSIFICATION SYSTEM FOR SOILS

DIRTY GRAVELS (WITH SOME FINES)

DIRTY SANDS

CLASSIFICATION IS BASED UPON

PLASTICITY CHART (we below)

WHENEVER THE NATURE OF THE FINE CONTENT HAS NOT BEEN DETERMINED, IT IS DESIGNATED BY THE LETTER "F", E.G. SF IS A MIXTURE OF SAND WITH SILT OR

PLASTICITY CHART

1. ALL SIEVE SIZES MENTIONED ON THIS CHART ARE US. STANDARD, A.S.T.M.

2. BOUNDARY CLASSIFICATIONS POSSESSING CHARACTERISTICS OF TWO GROUPS ARE GIVEN COMBINED GROUP SYMBOLS, E.G. GW-GC IS A WELL GRADED GRAVEL SAND MIXTURE WITH CLAY BINDER BETWEEN 5 % AND 12%.

~~ ~~

E. l l .

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and l i q u i d l i m i t is known as t h e p l a s t i c r a n g e a n d t h e

numer ica l d i f fe rence be tween t h e l i q u i d a n d p l a s t i c limits

i s c a l l e d t h e P l a s t i c i t y I n d e x .

I t w i l l be a p p r e c i a t e d t h a t where t h e n a t u r a l

water c o n t e n t is i n e x c e s s of the l i q u i d l i m i t , t h e s o i l

mass w i l l be most uns tab le and w i l l r e a d i l y flow i n t o

e x c a v a t i o n s o r t r e n c h e s . S u c h c o n s i d e r a t i o n s w i l l n o t

app ly where t he so i l mass i s kep t f rozen . However, i n

cases where t h e f rozen s o i l i s al lowed t o t h a w , t h e r e l a t i o n s h i p

be tween the na tura l water con ten t and l i qu id limit becomes

c r i t i ca l .

On page 5 there is a char t showing t he r e l a t ion -

s h i p b e t w e e n t h e P l a s t i c i t y I n d e x , t he Liquid L i m i t and

t h e group symbols of t h e Un i f i ed C las s i f i ca t ion Sys t em.

The A t t e r b e r g L i m i t system i s ex t r eme ly u se fu l f o r i d e n t i f y i n g

a n d c l a s s i f y i n g soils.

NOTES ON THE RADFORTH SYSTEM

FOR C L A S S I F Y I N G PEAT

The R a d f o r t h c l a s s i f i c a t i o n s y s t e m f o r d e s c r i b i n g

muskeg ( o r g a n i c t e r r a i n ) is a method f o r c l a s s i f y i n g t h e

three elements of vege ta t ion , t opography and o rgan ic su r f ace

cover us ing l e t t e r and f igure symbols . Height and type

o f vege ta t ion i s described by us ing cap i t a l l e t te rs ( A

through I ) . Topography i s d e s c r i b e d by us ing lower case

l e t t e r s (a th rough p) Organic cover type i f d e s c r i b e d

by u s ing f i gu res (1 through 1 6 ) .

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Table I ou t l ines t hese f i gu re symbol s and t h e

p e a t s t r u c t u r e a n d t y p e r e p r e s e n t e d by them. A complete

d e s c r i p t i o n of the Radfo r th sys t em i s con ta ined i n "Gu ide

t o a F i e l d D e s c r i p t i o n o f Muskeg" pub l i shed by N a t i o n a l

Research Counci l , O t t a w a , from which has been copied Table

I.

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TABLE I

SUBSURFACE CONSTITUTION

Predominant Charac t e r i s t i c Ca tegory N a m e

1. Amorphous-granular peat

2 . ?Jon-woody, f i n e - f i b r o u s p e a t

3 . Amorphous-granular peat containing woody f i n e f i b r e s

4 . Amorphous-granular peat containing woody f i n e f i b r e s

5 . Peat, predominantly amorphous-granular, c o n t a i n i n g non-woody f i n e f i b r e s , h e l d i n a woody, f ine f ib rous f ramework .

6 . Peat, predominantly amorphous-granular c o n t a i n i n g woody f i n e f i b r e s , h e l d i n a woody, coarse-fibrous framework.

7 . A l t e r n a t e l a y e r i n g o f non-woody , f i n e f ibrous peat and amorphous-granular p e a t c o n t a i n i n g non-woody f i n e f i b r e s .

8. Non-woody, f i n e - f i b r o u s p e a t c o n t a i n i n g a mound o f c o a r s e f i b r e s .

9 . Wood, f i n e f i b r o u s p e a t h e l d i n a woody, coarse-fibrous framework.

10. Woody p a r t i c l e s h e l d i n a non-woody, f i n e - f i b r o u s p e a t .

11. woody and non-woody p a r t i c l e s h e l d i n f i n e - f i b r o u s p e a t .

1 2 . Woody, coarse-f i b r o u s p e a t .

13. C o a r s e f i b r e s c r i s s - c r o s s i n g f i n e - f i b r o u s p e a t .

1 4 . Non-woody and woody f i n e - f i b r o u s p e a t h e l d i n a coarse-fibrous framework.

15. Woody mesh o f f i b r e s a n d p a r t i c l e s enclosing amorphous-granular peat c o n t a i n i n g f i n e f i b r e s .

1 6 . Woody, c o a r s e - f i b r o u s p e a t c o n t a i n i n g s c a t t e r e d woody chunks.

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