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F O U N D A T I O N

P ER FO R M AN C E O F

A S T EE L T OW E R

S I L O

J. D.

Scott1,

G. Haile2, and M . Bozozuk3

1

Hardy Associates 1978 Ltd., P.O. Box 746, Edmonton, Alberta, T5J 214; 2Geocon 1975 Ltd., 1130 Ouest rue Sherbrooke,

Montreal, Quebec, HiA 2R5; and }Geotechnical Section, Division of Building Research,

National Research Council of Canada, Ottawa, Ontario, K1A 0R6

Received 26 February 1979.

Scott, J.D., G. Haile, and M. Bozozuk.   979 Foundation performance of a steel tower silo. Can. Agric. Eng. 21: 85-89.

The foundation performance of a steel tower silo founded on a concrete circular raft ina deposit ofsoft clay wasmonitored in

order to determine the applicability of standard engineering foundation methods to this type of structure. The allowable bearing

capacity of the soil determined from field vane shear tests was more than adequate for the satisfactory performance of the

foundation. The measured settlement of the silo was about one third of that predicted. The settlement gauges showed that the

maximum soil compression occurred immediately below the foundation although the soil was highly overconsolidated by

desiccation. Becausefrost action occurred, the need todesignfor frost protection whensilo footings extend beyond thesilo wallat

a

shallow

depth is

discussed.

INTRODUCT ION

On 30 Sept. 1975 a ne w c o n cr e te t o w er

silo 32.3 m high, 9.14 m in diameter,

o v er tu r ne d w he n it was being filled fo r

th e

first t im e, b ec au se of a b ea rin g c ap ac i ty

failure

in

t he u n de r ly i ng

soil

  Bozozuk

1977;

1979).

Other

similar foundation failures of

tower

silos

h av e o cc ur re d B oz oz uk 1972;

Eden and Bozozuk

1962)

a nd n um ero us

cases of tilting of large

tower

silos because of

excess ive

s o i l se t t l ements ca n be

seen.

The concern

created among

farmers

an d

silo contractors abou t poor

foundation

performance re su lt ed in th e initiation of

research programs at

th e

Division

of

Building Research of

the National

Research

C o u n c i l o f C a n a d a a nd a t s e ve ra l

universities, to s t ud y t h e fo u nd a ti o n design

and performance of large tower silos. This

paper

reports

on th e results of on e

such

investigation.

T he f o un d at io n p e rf o rm a nc e s tu di ed is

for a steel

tower

silo founded on a rigid

circular c o n c r e t e r a f t e r e c t e d

in

1 9 7 6

adjacent

to the failed concrete silo. Th e

engineering properties of

th e

soil at

th e

site

were used to specify the dimensions fo r th e

f o u n d a t i o n

fo r

th e

n ew

si lo . T h e

performance of th e foundation was then

mo ni to red d ur in g lo ad ing in

order

to

confirm the application of engineering

foundation

theory

an d pract ice to thi s type

of s t ruc ture .

CHOICE OF

FOUNDAT ION

A

concise summary

concerning

th e

essentials for good foundation design was

given by Sowers 1970): 1) it must be placed

at an a de qu at e d ep th to p re ve nt f ro st

damage,

heave, undermining

by

scour, or

damage from future construction

nearby;

 2)

it

must

be safe against

b re ak in g i nt o t he

ground; an d  ) it m us t n ot settle enough to

disfigure

o r d am ag e th e

structure.

Th e first requirement

involves

a number

of decisions based

to

a t ar ge e x te n t on th e

s ou nd ju dg em en t a nd experience of th e

designer or bu ilder. Fo r th e other two

requi rements, i.e., the a ll owab le b e ari ng

capaci ty and set tlement of the

structure,

an

understanding

of th e

principles

an d

methods

of foundation engineering is

essential.

In g en er al , t he s el ec ti on

of

foundations

fo r large tower silos should follow t he s am e

procedure as that fo r

other

earth-supported

structures

such as

buildings,

warehouses an d

bridges.

Th e

soil

conditions

at

th e s il o s i te

should

be

a sc e rt a in e d a n d

its s tr en g th a nd

compressibility characteristics determined.

T h es e p r op e rt ie s m a y

be determined by field

or

laboratory

tests on undisturbed samples

of the soil. The procedure for calculating the

allowable

b ea ri ng c ap ac it y f or

tower

silos

founded in clay from these soil properties is

given by

Bozozuk

 1974).

Th e second step in foundation design

involves specifying

th e

thickness of

th e

foundation and

providing th e

necessary steel

reinforcement.

Th e

structural design of th e

foundat ion s h o u l d be done

in

accordance

with standard reinforced concrete design

procedures,

such

as

presented

by

Turnbull

an d Bellman 1977) for ring footings.

A lt er n at iv e ly , f o r m o st soil c o nd i ti o ns a n d

c o m m o n

silo

dimens ions , i n f o r m a t i o n

o n

th e size of footing

an d

on reinforcing ca n be

obtained f ro m desig n ta bles prepared by

Canada

Plan Services   Plans

7411 an d

7412). These plans give in t a bu l at e d fo rm t h e

maxi mum

sizes o f

t owe r

s ilo s

t ha t

c an b e

safely supported on soils with allowable

bearing

capacities varying

from 75

kP a

to

250

kPa .

SITE DESCRIPT ION

T he

site,

lo cated

10

k m s ou th -w es t

o f

Ottawa an d 7 km north o f Richm ond,

Ontario, is underlain by an overconsolidated

deposit of marine clay. Known as Leda clay,

the soil was depos ited in the sal ine

water

of

the Champlain Se a during

th e

recent episode

of

continental

glaciation   Gadd 1975).

Detailed discussions concerning the geology

of th e

clay

a r e a v ai la b le

elsewhere   Gadd

1975; Fransham

a nd G ad d

1977).

Th e soil profile together with water

c o nt e nt s, A t te r be r g

limits,

undrained shear

strengths

and preconsolidation

pressures is

presented in Fig. 1. T he t op 2.4 m consists of

desiccated an d oxidized brown clayey silt

below which the soil is

predominantly

soft

gray silty clay.

Th e

Atterberg limits ar e fairly

C A N AD I AN A G R IC U L T UR A L E N G IN E E RI N G. V O L .

21 ,

NO . 2, D E C E M B E R

1979

constant with

depth.

Th e plasticity index

an d

th e

liquid limit ar e

approximately

20

an d 40 , respectively. Within the oxidized

layer, th e liquid

limit

an d

th e

natural water

c o n te n t a re

about

t h e s am e . In the softerclay

l ay er b el ow

th e

desiccated crust,

however,

t he n at ur al w at er c on te nt s

average

52

an d

ar e higher than the l iquid l imits .

Figure 1

also

shows

th e

undrained

shear

s tr en g th a n d th e

rem o ul de d s h ea r

strength

determined by field vane tes ts . Within the

to p

layer, th e

a ve ra ge u nd ra in ed

shear

strength wa s about

60

kPa. Below th e

crust

an d to a d ep th o f 15 m, t h e u n d ra i ne d s h ea r

strength was fairly constant with an average

value of 36.5 kPa. Then it g raduall y

inc re a s e d to 6 0 kP a

a t

18

m .

Th e

remoulded strength

of th e soil gives

an

indication

of the sensi tivi ty of the clay to

disturbance. Th e average remoulded

shear

strength

of 5

kP a

compared

to the average

u nd is tu rb ed s he ar s tr en gt h

of

36.5 kP a

indicates that th e soil is very sensitive to

dis turbance .

From t he d is tr ib ut io n

of th e

m o s t

probable preconsolidation pressure

an d

the

in s it u ve rt ic al e ff ec ti ve s tr es s, it wa s

concluded that th e desiccated l ayer was

o v e rc o n so l id a t ed b y about 100 kPa, while

th e underlying clay was overconsolidated by

only about 20

kPa.

F r o m Bozozuk   1974), a

soil

shear

strength of

36.5

kP a will

allow

a foundation

bearing

value

of 81

kP a

with a safety factor

of 3 a ga ins t b ea r in g capacity fa ilure for a

c i r c u l a r

foundat ion.

Th e

possible

settlement

of a structure

with a foundation pressure of this

m a gn itu d e d ep en ds on the

distribution

of

th e

m a x i m u m

v e r t ic a l s t re s s in

th e

s oi l m a ss

in relation to the overconsolidation pressure

o f th e

s o il.

T h e i n cr e as e

in

ver t i cal

stress

a t

t he b as e of

t he f o u nd a ti o n

would

be 81 kP a

m in us t he p re ss ur e f ro m the excavated soil,

an d it

would

decrease

with

depth.

Fo r th e

soil c on di ti on s a t th e

site,

th e

soil

in

th e

upper 3 m w o ul d u n d e rg o little compression,

while

significant

bu t tolerable settlements

would

occur in th e soil beneath this depth.

An allo wab le b earin g

value

o f 81 kPa,

therefore, wa s c h o s e n as th e limit for the

concrete raft to support th e new silo.

8 5

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DEPTH

METR ES

S O I L

T Y P E

W TER O NTE NT

 N

ATTERBERG LIMITS

  )

SHEAR STRENGTH AND VERTICAL STRESS

  kPa)

^Ground

. Su r f a c e

El. 107m

20 4 0

6 0

_J

. I .

L_

20 40 60

80

100 120 140

—I 1 1 1 1 1 L i I • i . i

-Raft Depth

0 .72

m

- 5

clay,

sllty

b r o w n I

 n.

i K

—

I t

1 •. .

10

clay, sllty

grey

-u* :•.* ••

i 1

 15

  :

20

clay, sllty

brittle grey

Wp

w,

DESCRIPT ION

OF S TRUCTURE

T h e steel t o w e r

s ilo

w a s e r ec t ed

in

June

1976. It ha d an inside diameter

of

7.6 m,

of 26 m e xc lu d in g t he

roof, an d

a

of

about

950

tonnes.

In order

t o

ensure

tha t

the re mou lded

s o il

th e

failed co n crete

silo

di d n ot

a ffe c t

performance of th e new s t ru c tu r e, t h e

dge of

th e

new

foundation

was

located

6 m from the zone of d isturbed clay.

ig. 2 shows the relat ive

position

of the raf t

to th e

f ai le d s il o

a n d

th e

b arn .

Th e

raft foundation,

13.7 m in

diameter,

as founded at a

depth

of 0.72 m Fig. 3).

he figure also shows the concrete pedestal

ast on

to p

of

th e

raft.

Th e

pedestal

is

th e

a nd ard Ha rv e st o re foundation normally

ed to support th e silo when soil conditions

e a de qu at e.

Th e

s ta nd ar d H ar ve st or e

u n da ti on a nc h or s t he

s t ee l s i lo a t

it s

b a s e

nd contains the

trough

for the

unloading

syst em.

Steel

reinforcing

for

the raft

was

by adding 20 mm

radial

bars 3.1 m

n g p la ce d 8 cm above the b ot to m o f t he

Th e

reinforcing

bars were

3.2 m

f ro m t he c en te r of

th e

raft

a

uniform spacing of

0.15 m

around th e

ilo perimeter. To hold them in pos it ion,

were fastened at both ends to 20 mm

st eel re inforc e me nt.

T h e to ta l

de a d

m a s s

of th e foundat ion

d

silo was

approximately

630

tonnes.

6

Figure 1. Soil p ro fi le at raft

location.

Figure 2. Raft foundat ion for tower silo. Portion of failed silo in the background.

I NS TRUMEN TA T IO N AND

OBSERVAT IONS

T he p er fo rm an ce of

th e

silo

during

loading

a nd th e r ea cti on of t he u n de r ly i ng

soil to the load were monitored by th e

ins ta lla tion of i ns tr um e nt s t o m e as ur e th e

settlement

a n d d e f or m a ti o n of th e

raft,

th e

zone

o f c o mp r es s io n

in

th e

s oi l m as s,

th e

p or e w at er pressures beneath

th e

silo,

an d

th e

contact

pressure

distribution

on th e base

o f

th e raf t .

T h e i n s tr u m e n t a t i o n cons i s ted o f

a

deep

bench mark

driven

to th e b otto m

of

th e clay deposit, 24 levelling points

on

th e

raft  12

around

t h e c i rc u m fe r en c e of th e silo

and 12 ar ound the edge of the raft), six deep

settlement

gauges, tw o Gloetzl

pneumatic

and four Geonor

standpipe

piezometers,

a nd ei gh t G lo et zl hydraulic

earth

pressure

cells. Th e locations ar e given in Fig. 3.

CANADIAN

AGRICULTURAL ENGINEERING, VOL. 21, NO. 2,

DECEMBER

1979

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GROUND

SURFACE

STEEL

SILO

WALL

CONCRETE

PEDESTAL

ON TOP OF RAFT

 P -3

LEGEND

C-l to C-8 LOAD

CELLS

P-l

to

P-6

PIEZOMETERS

* LEVELLING POINTS Concrete Nails

P 5

  p - 4

  . . _ 0 1.0 2.0m

S CA L E I i i

Th e l oa d -s e tt l em e nt r e la t io n sh i p

is

plotted in Fig. 4. The load was applied

c on ti nu ou sl y d ur in g construction an d

subsequent fil ling of th e silo with haylage

over a period of about 50 d a ys , w h ic h r ai se d

th e

applied

net pressure to about 55 kPa.

Th e

settlement du e to this loading was about

7 mm. In

t h e f o ll ow in g

150

d ay s w hen

a

small additional

load

was applied an d

remo v ed , a f u r t h er s e t tl e m e nt o f 4

m m

t o o k

place. During the last 50 days of this per iod

ending in

December

1976, th e

settlement

was less

than

1 m m , i n di c at in g a v er y s lo w

rate

of

settlement. Frequent

settlement

surveys were

discontinued

in February 1977,

w h e n

it

w as

d i s c o v e r e d

t ha t th e silo h ad

h e a v e d more than

3

m m due

to f r o s t

penetration

of the

underlying clay

through

th e concrete raft that

extended

b ey on d t he

s i l o

wa l l .

By October 1978,

when the silo

ha d

undergone

tw o

cycles of loading

an d

unloading, and

was

loaded

for

t h e t h ir d t im e

to a net applied pressure of 65 kPa, the

P 6

6

DEEP

BENCH M RK

Figure 3. Section

through

silo, showing

foundation

and instrumentation.

s e tt le m e nt h a d

reached

a

total o f

21 m m .

Th e

d i ff e re n t ia l s e t tl e m e n t

o f

the raft

monitored with the 24 levelling points

showed that the raft was very rigid. The

average

differential

movement

wa s

in th e

o rd er o f

1

mm, even when the entire

structure was lifted by frost action on only a

part of

its

base.

The settlement gauges showed that

about

90 of the soil compression took place in the

upper 14 m

of

th e soil profile a n d a lm os t o ne

half

o f

this s e tt le m e nt o c cu r re d i n

th e

4 m

o f

soil d ir ec tl y b e lo w t h e raft. This

settlement

pattern was fairly constant over

t he e nt ir e

loading range and has not changed with

t i m e .

The excess pore water pressures were

very low compared to the pressures applied

during construction. The excess pore water

pressures of approximately 6 kP a

indicated

that

the silty clay drained rapidly

during

the

construction and loading period of less than

50

days and

that

t he o bs er ve d s et tl em en ts

we re d ue t o b ot h e l a st i c s o i l m o v e m e n t s a n d

CA N A DI A N A G RICU L TU RA L E N G IN E ERI N G,

VOL 21, NO. 2,

DECEMBER

1979

consolidation. Th e excess pore pressures

were

almost

completely dissipated 60 days

af ter

th e silo w as filled.

Th e

earth

pressure cells at th e base of th e

raft indicated that the contact pressure

dis tribution

acros s th e foundation wa s

n o n u n i f o r m a n d

c o n s i s t e n t

with

elastoplastic

t he or y f or s u ch f o un d at io n s.

When the average gross contact pressure

from t he d ea d a nd

live loads was 72

kPa,

the

a ct ual c ont ac t

pressure was approximately

80 kP a at th e edge, reducing to about 50 kPa

t owards t he c en te r

of

th e r af t .

S E T T L E M E N T

O F

SILO

Although

reliable

m e th o ds a re available

for estimating the a ll o wa b le fo un d at io n

pressure to ensure an

adequate

factor of

safety against a bearing capacity failure, it is

diff icul t to predict the set tlement that this

load will p ro du ce . T h e t ot al settlement of a

structure

will be composed of: a) an

im me dia te se ttle m en t d u e

to

lateral

deformation

of the underlying soil under the

influence of the applied load; and b) long-

t er m c on so li da ti on

o f th e soil du e

to

dissipation of excess pore water pressures.

T h e

e st im a te d t he o re ti ca l i m m e d i a t e

settlement

was compared to the obse rved

settl ement for pressure levels of up to 55

kPa. The estimatewas based upon the secant

m od ul i o b ta in ed f ro m t ri ax ia l

stress-strain

curves. At the higher pressures , the loads

were

applied

slowly

allowing consolidation

to take place at the same time; consequently

th e

i m m e d i a t e

s e t t l e m e n t s were

n o t

determined.

Stress-strain curves for

 

isotropically

consolidated undrained   CIU)

triaxial tests

at v ar io us d ep th s w er e a va il ab le .

Th e

compressible zone

below

th e

bottom of the

raft was therefore divided into   soil layers

and the

calculated

compressions of the

layers were added to give the total settlement

of the raft. The compression of each layer

wa s calculated from:

 a) estimated

vertical

a n d

lateral s tr es s i nc re as es d u e to th e

foundation pressure at the centerof the layer

f rom elast ic theory, b) the secant modulus

de termined from the part icul ar triaxial

s tress-st rain curve corresponding to the

v e r ti c a l s t re s s

i nc r ea se e st im a te d a b ov e a n d

c) the compression of the soil layer

determined from elastic theory. Elastic

formulae

relating stress an d strain are found

in many soil m ec h an i cs t ex t bo o ks . It is

c om m on to us e

a

P o is so n s r at i o o f 0. 5 fo r

calculations o f

immediate

settlemen t in

saturated

clay

soils.

In general,

th e

estimated

settlements

were

grea te r t han

observed. For example,

corresponding to a net applied pressure of 55

kP a

th e ca lc ula te d a n d m e a su r e d

immediate settlements were 13.5 an d 7 mm

respectively. Th e

main reason

for the

discrepancy was th e low m o du l i o bt ai ne d

from

th e

uniaxial tests. Lo w

moduli

ar e

caused by disturbance in obt aini ng and

preparing samples. Th e total

immediate

settlement at the maximum pressure applied

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NET APPLIED PRESSURE kPa

30 40_

_50_

60

70

 

Figure 4. Settlement of silo raft foundation.

f 65 k P a wa s c a lc ula te d

to

be 16 m m .

Based upon the maximum net applied

essure of 65 kPa, the predicted long-term

consolidation

set t l em en t ,

fro m

s ta nd ar d o d om e te r te s t

sul ts, was about 46 mm. The total

edicted settlement was therefore 62 mm.

addition, creep-type settlements could

cur in the clay because the total vert ical

pplied stress was

about

equal

to or

ceeded the preconsolidation pressure of

e clay between 4 and

 

m of depth.

Th e

eventual total

settlements

will,

wever, not be

much

greater than th e 21

m m easured in

O c t o b e r 1978. T h e

m ed ia te a nd cons olidation settlemen ts

ppeared to be complete but addi tional

ettlement will p robab ly occur due to a)

ading and unloading of the silo, and b)

creep.

B o t h

th e

c a lc ula te d

a nd m ea su re d

t o t a l

tlements discussed previously were based

n the maximum net applied pressure of 65

a . T he

raft

was,

however, dimensioned

to

a net

increase

in

a v er ag e v er ti ca l

essure of 72kPa. If the silo was filled with

avier silage so

that

the applied pressure

ould be greater

than

65 kPa, both the

edicted and measured settlements would

larger.

F RO S T A C TIO N

The unexpected frost heave of the silo

f t i nd ic at ed

a relat ively

m in or p ro bl em

th th is

sh allo w

f ou n da ti on . O t h er silos

have t he ir f ou nd at io ns placed

eper than the

depth

of frost penetration. A

deeper foundation in this case would have

m e a n t

a

s ubs tantial increase

in

m a t e r i a l

costs an d changes

in design to

allow

th e

n o rm a l u n lo a di n g

of

th e

silo. In

general

a

tall, heavy silo such as this one may require a

wide footing extended well beyond the silo

wall

which would no t

be

protected

by

th e

insulating

an d

heating effects of the silage.

Frost heave pressures under t h e t o e c o ul d

break the footing. When the silo raft heaved,

th e earth pressure cells showed that the

central

part

of the

foundation

was lifted

clear of

th e

under ly ing soil by th e uplift

pressures acting around the edge. The

considerable

t hi ck ne ss a n d

rigidity

of

th e

raft prevented it f rom being damaged but a

normal

footing would probably have been

cracked and damaged. Such footings

t h er e fo r e s h ou ld

be

p la c ed b el o w th e depth

of frost penetration, or reinforced to

withstand the uplift pressures. It may be

more economical

to

protect the foundation

by placing insulation below or a bo ve t he

footing extension or by bui ld ing an earth fill

around th e

silo to

prevent

excessive

frost

penetration.

SUMMARY AND CONCLUS IONS

Th e a ll o wa b le g ro ss b e ar in g p re ss ur e

of

81 kP a

determined

by

commonly

used

foundation engineering methods resulted in

a safe design for bearing capacity. Th e

performance of this foundation supported

t h e c o nc l us io n by

Bozozuk

 1977)

that clay

soil s trengths measured in situ with a field

vane can

be used to

p re di ct t he u lt im at e

bearing capacity.

Th e

observed

total settlements w e re o n ly

about

o ne t hir d

of

those

p re di ct ed f ro m

laboratory

tests

on soil samples. The

difficulty in

estimating

s m al l s et tl em en ts

resulted from

th e

sensitivity

o f

soil

stress-

s t ra in c h a r a c t e r i s t i c s

to d is tu rb an ce th at

n or mally o ccu rs

d ur in g s ampl ing

an d

handling.

Th e

relatively small settlement of 21mm

indicated that the factor of safety of

3

against bearing

failure,

commonly

used for

buildings sensi tive to settlement, could be

r ed uc ed f o r

fa rm s ilo s .

T he a l lo w a b le t o ta l

s e t t l e m e n t o f mos t st ructures is

l i mi t ed

to

appproximately

25 mm to ensure

that

differential

settlements will

no t disfigure

or

damage the building. Th e rigidity of circular

tower silos should

allow

g re ate r to tal

settlements without damage; consequently it

may be

appropriate

to r ed uc e t he factor of

safety to

about

2.5, which would resul t in

s m a l l e r

and m ore econom ic

foundat ions .

This may, h owev er, i nc rea se t h e stresses in

t h e foundat ions b e c a u s e of

varia t ions i n s oi l

compressibility. It would

then

become most

important

to include

adequate

reinforcing in

th e

footings.

Th e large percentage of th e total

s e t t l e m e n t

w h i c h

o c c u r r e d in t he 4 m o f soil

immediately below th e f o un d ation was no t

predictable from

consideration

of the soil

profile or results of the laboratory tests. This

zone

of soil

wa s

overconsolidated

by

d es ic ca ti on a nd appeared to be relatively

incompressible

compared

to th e underlying

softer clay. T hi s f inding emphasizes the

importance

of placing footings deep

enough

so that the highly stressed region immediately

b e n e a t h f o u n d a t i o n s

d o es

n ot o cc ur in soil

that has been excessively

disturbed

by

weathering an d f ro s t a c ti o n.

Foundations that

ma y

be affected by

frost a ct io n s ho ul d

be

placed below the

depth

of frost

penetration.

If this is not

possible, th e foundation should be protected

with adequate insulation or reinforced with

steel to w it hs ta nd t he b en di ng m om en ts . If

frost

action

ma y c au se d if fe re nt ia l

movement, hence tilt ing

of th e silo,

however,

t h en fros t protection

r a th e r th an

foundation

strength should be the criterion for design.

ACKNOWLEDGMENT S

Th e

steel

tower

silo wa s

manufactured

by

A.O.

S mi th , H ar ve st or e P ro du ct s Inc., I ll inois, an d

erected by

Ontario

Harvestore Systems Ltd. This

research study was made poss ib le by f inancial

assistance from the

Ontario

Ministry

of

Agriculture and Food,

Ontario

Harvestore

Systems Limited, and the Division of Building

Research of th e National R e s e ar c h C o u nc i l.

BOZOZUK, M. 1972.

F oundat i on

failure of

th e

Vankleek

Hill tower silo. Proc. Spec. Conf.

Earth an d Earth -Su p p o rted Structures,

AS C E ,

S M F D , 1 2): 885-902.

BOZOZUK, M. 1974.

Bearing

capacity of clays

f or t ow er silos. Can. Agric. Eng. 16 1): 13-17.

BOZOZUK, M. 1977.

E val uat i ng st r engt h

tests

f r om f o u n d a t i o n

failures.

Pr oc . 9t h Int.

Co n f .

Soil

Mech. F ou n d. E ng .. T o ky o , 1: 55-59.

C A N A DI A N A G R I C U L TU R A L ENGINEERING, VOL.

21,

NO .

2. D E C E M B E R 1979

8/19/2019 Steel Foundation

5/5

BOZOZUK, M. 1979. Problems with concrete landslides in Ottawa Valley, Ontario. Can. Introductory soil mechanics and foundations.

tower silos. Can. Agric. Eng. 21: 69-77. Geotech. J.

14 4 :

531-537. The Macmillan Company, London.

EDEN

W.J.

and M. BOZOZUK. 1962.

GADD, N.R.

1975.

Geology

of Leda clay. Proc. TURNBULL, J.E. and H.E.

BELLMAN.

1977.

Foundation failure of a silo on varved clay. 4th Guelph Symp. on Geomorphology, Reinforced extended ring foundations.

Eng. J. 45 9 : 54-57. Geological Survey

of

Canada Library, MGF Canadian Society

o f

Agricultural

FRANSHAM, P.B. and N.R. GADD. 1977. 9S98 4th. Engineering, Annual Meeting, 14 to 18 Aug.

Geological and geomorphological

controls of

SOWERS, G.B. and G.F. SOWERS. 1970. Guelph,

Ont.

CANADIAN

AGRICULTURAL

ENGINEERING, VOL. 21, NO. 2, DECEMBER 1979 89