Use of ice landings

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Use of ice landings

NATIONAL RESEARCH COUNCIL CANADA D I V I S I O N OF BUILDING RESEARCH U S E OF I C E LANDINGS b y L.

w.

Gold

Internal Report No. 229

of

the

Division

of B u i l d i n g Research

OTTAWA A u g u s t 1961

PREFACE

This r e p o r t i s one of s e v e r a l r e p o r t s and papers which have been prepared by t h e Snow and I c e Section of t h e Division a s a c o n t r i b u t i o n t o t h e s a f e use of i c e covers f o r t r a n s p o r t and f o r pulp wood landings. A s i s o f t e n t h e case i n engineering a p p l i c a t i o n s , t h e r e i s much t o be learned from c a r e f u l

study of f i e l d experience. The Division has been p r i v i l e g e d t o have very s u b s t a n t i a l co-operation from t h e Canadian Pulp and Paper Association and i n

p a r t i c u l a r from some of t h e member companies i n t h e c o l l e c t i o n and submission of f i e l d information, some of which i s now presented and analyzed.

The a u t h o r , a r e s e a r c h o f f i c e r with t h e Division, i s head of t h e Snow and I c e Section, and has devoted much time t o s t u d i e s of t h e s t r e n g t h of

i c e .

Ottawa

USE I C E LANDINGS

I,. W. Gold

A Survey on Loads Placed S u c c e s s f u l l y on I c e Covers

I n t h e f a l l of 1958 t h e Snow and I c e S e c t i o n of t h e Division of Building Research, i n co-operation with t h e

Canadian Pulp and Paper A s s o c i a t i o n , and through t h e Associate Committee on S o i l and Snow Mechanics of t h e National Research Council, undertook a survey on t h e f a i l u r e s of i c e covers t h a t occurred during t h e c o n s t r u c t i o n and use of i c e l a n d i n g s f o r wood s t o r a g e b y pulp and paper companies. The observa- t i o n s obtained i n t h e w i n t e r s of 1958-59 and 1959-60 have been r e p o r t e d (1). These o b s e r v a t i o n s showed t h a t many of t h e v e h i c l e s broke through i c e t h a t would normally have been considered t h i c k enough t o support t h e l o a d s a p p l i e d . This

i n d i c a t e d t h a t f a c t o r s o t h e r t h a n i c e t h i c k n e s s were probably r e s p o n s i b l e f o r some of t h e f a i l u r e s t h a t occurred i n t h e course of normal o p e r a t i o n s on t h e landings. To o b t a i n f u r t h e r evidence on t h i s p o i n t , a study was undertaken i n t h e w i n t e r of 1960-61, of t h e l o a d s which pulp and paper companies s u c c e s s f u l l y placed on frozen l a k e s and r i v e r s , and of t h e a s s o c i a t e d i c e t h i c k n e s s e s .

Rose and S i l v e r s i d e s e s t i m a t e t h a t soae 10 t o 15 m i l l i o n t o n s of pulp wood a r e placed on i c e covers each

w i n t e r ( 2 ) . To a t t e m p t t o record a l l t h i s a c t i v i t y would be u n r e a l i s t i c . With t h e a s s i s t a n c e of t h e Canadian Pulp and Paper A s s o c i a t i o n , arrangements were made f o r 4 companies t o each r e c o r d , on s p e c i a l forms, d e t a i l s concerning t h e i c e cover and t h e wood placed on one landing. During t h e w i n t e r , o t h e r companies i n d i c a t e d t h e i r w i l l i n g n e s s t o p a r t i c i p a t e i n t h e survey and c o n t r i b u t e d observations. Table I r e c o r d s t h e approximate s i z e of t h e l a n d i n g s observed, t h e approxi- mate weight of t h e wood placed on t h e l a n d i n g , and t h e

number of t r i p s r e q u i r e d t o place t h e wood.

Besides a complete r e c o r d f o r one l a n d i n g one company submitted a p a r t i a l record of t h e wood placed on 6 a d d i t i o n a l landings. This r e c o r d , summarized i n Table 11,

included t h e t o t a l number of cords of wood placed, t h e a s s o c i a t e d number of t r i p s , d e t a i l s on i c e t h i c k n e s s and

sample o b s e r v a t i o n s of t h e d a i l y t r a f f i c . These o b s e r v a t i o n s were n o t complete enough t o be included i n t h e g e n e r a l

a n a l y s e s b u t samples of d a i l y t r a f f i c i n d i c a t e t h a t t h e y support t h e g e n e r a l conclusions obtained from t h e observa- t i o n s i n Table I.

When completed, t h e survey had recorded over 64,000 l o a d s f o r a t o t a l of over 850,000 t o n s of wood placed on i c e covers. !J?welve breakthroughs only were r e p o r t e d d u r i n g t h e p l a c i n g of t h i s wood. Eight companies placed t h e i r wood

without any f a i l u r e s . Some of these companies have operated t h e i r landings f o r 2 o r more years without accident.

OBSERVATIONS

-

A s p e c i a l form was prepared and d i s t r i b u t e d t o t h e companies p a r t i c i p a t i n g i n t h e survey (Fig. 1). This form was used d a i l y t o record t h e t o t a l weight of wood placed on

each landing, t h e number o f t r i p s required t o place t h i s wood, t h e type of v e h i c l e s used, the weight of t h e l a r g e s t load

placed, t h e thickness of t h e i c e cover and t h e thickness o f t h e white i c e . From observations on t h e number of t r i p s and t h e t o t a l weight of wood placed, t h e average weight per t r i p

on i c e of given e f f e c t i v e thickness could be c a l c u l a t e d , Information on. the maximum loads would i n d i c a t e t h e spread

in

s i z e o f the loads allowed on t h e i c e during t h e period f o r which average loads were c a l c u l a t e d .

ANALYSIS OF TI333 OBSERVATIONS

Theoretical considerations show t h a t t h e maximum s t r e s s , S, produced , i n an i c e cover i s d i r e c t l y . p r o p o r t i o n a 1 t o t h e applied load, P, and i n v e r s e l y proportional t o t h e square o f t h e e f f e c t i v e t h i c k n e s s , h ; i . e . ,

where C i s a p r o p o r t i o n a l i t y f a c t o r t h a t depends on t h e p r o p e r t i e s of t h e i c e , t h e geometrical configuration of t h e load, t h e l o c a t i o n of t h e load with r e s p e c t t o cracks i n t h e cover and t h e nature of these cracks. The e f f e c t i v e thickness was obtained by adding one-half o f t h e measured thickness o f white i c e t o t h a t of good c l e a r i c e . With a good i c e s h e e t and moving v e h i c l e s whose wheel geometry does n o t change very much from one vehicle t o another, C can be considered constant.

= S/C i s c a l l e d the "ice loadingN i n t h i s r e p o r t . The r a t i o -2

h

From the records, the observed values of t h e average l o a d ,

H,

and the maximum load An f o r each landing were determined f o r e f f e c t i v e i c e thiclmesses i n s t e p s of 1 i n , I n Pig. 2 ,

?

i n l b i s p l o t t e d a g a i n s t e f f e c t i v e i c e thickness h , i n i n , Shown i n t h e same f i g u r e f o r reference a r e t h e l i n e s defined

2

by P=50h and P-250h2. A l l breakthroughs reported t o d a t e have 2

occurred f o r loads g r e a t e r than P-50h (1). P=250h2 d e f i n e s approximately t h e upper s a f e l i m i t t h a t has been recommended i n t h e l i t e r a t u r e f o r those s i t u a t i o n s where some r i s k i s

acceptable. The r a t i o of and

Fm

t o t h e square of t h e e f f e c t i v e t h i c k n e s s of t h e i c e was c a l c u l a t e d . I n Pig.

3 ,

0 r,

H/hL

i s p l o t t e d a g a i n s t t h e i c e t h i c k n e s s along with P f a i l / h d obtained from t h e breakthroup;h r e p o r t s received t o date.

?/h2 i s p l o t t e d a g a i n s t Fm/h2 i n Fig.

5.

Figure 4 shows t h e observed number of loads placed on t h e i c e during t h e i c e use survey f o r each i c e t h i c k n e s s i n s t e p s of 1 i n . I n t h e same f i g u r e i s shovm t h e number o f breakthroughs recorded s i n c e t h e f a l l of 1958.

It could be argued t h a t t h e c a l c u l a t i o n o f e f f e c t i v e i c e thickness i n t h e manner done i n t h i s r e p o r t i s n o t j u s t i f i e d , The r u l e of giving t o white i c e an e f f e c t i v e thickness of h a l f i t s measured thickness i s one which has been adopted b~ a

nuinber of authors. It probably o r i g i n a t e d from i n v e s t i g a t i o n s made by t h e Russians p r i o r t o 1939. I t s continued use i s n o t an i n d i c a t i o n of i t s v a l i d i t y but r a t h e r of t h e l a c k of know- ledge on t h e s t r e n g t h p r o p e r t i e s of white i c e . 'kis r u l e was used i n (1) and has been adopted i n t h i s r e p o r t f o r t h e

following reasons:

(1) The q u a l i t y of t h e white i c e formed on t h e landings i s v a r i a b l e . The .mechanical p r o p e r t i e s of t h i s i c e depend upon i t s q u a l i t y .

( 2 ) The bonding s t r e n g t h between successive l a y e r s of white i c e i s v a r i a b l e . Some breawhrough observations

i n d i c a t e a f a i l u r e of t h e cover between such l a y e r s . ( 3 ) It i s u n l i k e l y t h a t properly prepared white i c e has a

s t r e n g t h a s low a s one-half t h a t of good c l e a r i c e ( 5 ) . Assuming t h a t it does have a s t r e n g t h equivalent t o one- h a l f i t s thiclmess of c l e a r i c e w i l l ensure t h a t t h e r e s u l t i n g p r e d i c t i o n of t h e bearing c a p a c i t y w i l l be on t h e s a f e s i d e .

( 4 ) Assigning t o white i c e t h i s e f f e c t i v e t h i c k n e s s w i l l draw a t t e n t i o n t o t h e f a c t t h a t t h e s t r e n g t h of such i c e i s l e s s than t h a t of good c l e a r i c e and t h a t it depends upon t h e q u a l i t y and t h u s upon t h e techniques used i n preparing t h e landing.

Calculating t h e e f f e c t i v e t h i c k n e s s i n t h i s way w i l l normally change t h e measured thickness by no more than

25 p e r c e n t and u s u a l l y l e s s than 15. Changing thicknesses by t h i s amount w i l l n o t g r e a t l y a f f e c t t h e l i m i t s on t h e bearing c a p a c i t y of i c e covers obtained from t h e present surveys, n o r w i l l

it

s i g n i f i c a n t l y modify t h e general con- c l u s i o n s t h a t were obtained from t h e study on t h e use of i c e landings.

DISCUSSION

Figures 2 and

3

show t h a t many of t h e r e p o r t e d i c e f a i l u r e s occurred f o r l o a d i n g s t h a t a r e normal f o r o p e r a t i o n of t h e Pulp and Paper I n d u s t r y . This confirms t h e observa- t i o n t h a t f a c t o r s o t h e r t h a n i c e t h i c k n e s s must be r e s p o n s i b l e f o r t h e s e f a i l u r e s .

To d e f i n e more p r e c i s e l y some of t h e f a c t o r s t h a t could be c o n t r i b u t i n g t o t h e i c e f a i l u r e s , a r e v i s e d break- through r e p o r t was prepared and d i s t r i b u t e d i n t h e f a l l of 1960, Besides t h e s p e c i f i c information deemed important from e a r l i e r breakthrough o b s e r v a t i o n s , a n opinion a s t o t h e cause of t h e f a i l u r e was requested. The breakthrough observa- t i o n s obtained d u r i n g t h e w i n t e r of 1960-61, combined w i t h t h e o b s e r v a t i o n s of previous y e a r s , confirmed t h a t v e h i c l e speed i s one c o n t r i b u t i n g f a c t o r . For i c e t h i c l m e s s e s and water depths normal f o r l a n d i n g s , v e h i c l e speed should be

kept below

5

_{mph t o ensure t h a t t h e cover w i l l n o t be unduly}

s t r e s s e d by t h i s e f f e c t .

Reports showed t h a t some f a i l u r e s may be a s s o c i a t e d w i t h a drop i n temperature s u f f i c . i e n t t o cause thermal c r a c k s

i n t h e i c e . Observers commented on t h e very b r i t t l e n a t u r e of t h e i c e under t h i s c o n d i t i o n . This b r i t t l e behaviour may be due t o t h e presence of thermal s t r e s s e s . Such observa- t i o n s suggest t h a t e x t r a p r e c a u t i o n be t a k e n when p l a c i n g l o a d s on i c e covers f o l l o w i n g a marked drop i n temperature, and i n p a r t i c u l a r t o keep v e h i c l e s w e l l away from any cracks.

Some of t h e f a i l u r e s occurred on t h e a c c e s s roads from t h e shore under c o n d i t i o n s t h a t suggest e r o s i o n of t h e i c e from c u r r e n t s o r a b r i d g i n g e f f e c t between t h e shore and t h e f l o a t i n g i c e cover, a p o s s i b l e r e s u l t of lowering t h e water l e v e l . A number of f a i l u r e s were a s s o c i a t e d w i t h m u l t i - l a y e r e d i c e covers, i . e . i c e l a y e r s s e p a r a t e d by a pocket o f w a t e r o r a i r , Such d e f e c t s i n t h e cover may be caused by a changing water l e v e l o r poor f l o o d i n g p r a c t i c e .

During a v i s i t t o one o f t h e l a n d i n g s , t h e foreman described a n o t h e r source of f a i l u r e confirmed l a t e r by one of t h e breakthrough r e p o r t s . If t h e l o a d s a r e l a r g e enough t o c r a c k t h e i c e under t h e v e h i c l e , t h e n continuous use of a road by v e h i c l e s c a r r y i n g such l o a d s can c a m e severe c r a c k i n g and a c o n s i d e r a b l e d e p r e s s i o n of t h e i c e i n t h e immediate

v i c i n i t y , This d e t e r i o r a t i o n of i c e by t r a f f i c can be con- t r o l l e d by moving t h e road a t l e a s t one t r u c k width about every two h o u r s , depending on t h e t r a f f i c .

An i n t e r e s t i n g f a c t which t h e survey r e v e a l e d was

_-

t h e marked d e c r e a s e i n t h e r a t i o ~/h'! a s t h e t h i c k n e s s of i c e i n c r e a s e d . The reason f o r t h i s i s obvious. For each l a n d i n g t h e r e i s a p a r t i c u l a r i n c r e a s e i n i c e t h i c k n e s s w i t h time and

s o t h e i c e t h i c l m e s s a x i s i n P i g s .

3

and

4

can be v i s u a l i z e d a s a time s c a l e . A t a given i c e t h i c k n e s s , u s u a l l y about 16

i n . f o r most l a n d i n g s , l o a d s a r e allowed on t h e i c e . Experience h a s determined t h e s i z e of t h e l o a d t h a t can be placed on t h e

i c e a t t h i s time. Por a f i v e t o n t r u c k t h i s i s u s u a l l y 8 t o 10 t o n s , a l i t t l e o v e r

&

t h e c a p a c i t y of t h e t r u c k , g i v i n g a g r o s s weight of about 20 t o n s . A s q u i c k l y a s p o s s i b l e , t h e l o a d s a r e i n c r e a s e d t o t h e f u l l c a p a c i t y of t h e t r u c k . This l o a d i n g of 20 t o 25 t o n s i s u s u a l l y achieved by t h e time t h e i c e i s 20 i n . t h i c k . For i c e t h i c k n e s s g r e a t e r t h a n 20 t o 25 i n . t h e f a c t o r l i m i t i n g t h e s i z e of t h e l o a d placed, on t h e i c e i s t h e c a p a c i t y of t h e t r u c k and n o t t h e t h i c k n e s s of t h e i c e . When t h e maximum l o a d i n g of t h e t r u c k h a s been reached, t h e i c e l o a d i n g d e c r e a s e s w i t h i n c r e a s i n g i c e t h i c k - n e s s ( F i g .

3 ) .

A t any time t h e maximum l o a d on t h e l a n d i n g s under o b s e r v a t i o n was u s u a l l y w i t h i n 20 p e r c e n t of t h e average l o a d

( F i g . 5 ) . This i s probably because t h e r e was normally n o t a v e r y l a r g e v a r i a t i o n i n t h e c a p a c i t y of t h e t r u c k s used on each l a n d i n g and each c a r r i e d t h e g r e a t e s t p o s s i b l e load. A

n o t a b l e e x c e p t i o n i s shown by t h e o b s e r v a t i o n s p l o t t e d a s c i r c l e s where t h e maximum l o a d s g r e a t l y exceed t h e average

l o a d s , p a r t i c u l a r l y f o r t h e h i g h e r loadings. It i s of i n t e r e s t t h a t 5 of t h e 12 breakthroughs recorded i n t h e i c e use survey occurred on t h i s landing.

It i s a common f i e l d o b s e r v a t i o n t h a t c r a c k i n g occurs i n t h e immediate v i c i n i t y of a v e h i c l e when t h e i c e

2 2

l o a d i n g , P/h

,

i s about 150 l b / i n

.

This i n d i c a t e s t h a t t h e i c e l o a d i n g f o r c o l l a p s e of t h e i c e cover i s probably l e s s

n

t h a n 300 l b / i n L ( 3 , 4 ) . The maximum l o a d r e p o r t s contained i n t h i s r e p o r t and

i n

(1) show t h a t t h e i c e l o a d i n g f o r t h e

_-

c o l l a p s e of a good i c e cover must be g r e a t e r t h a n 250 l b / i n 2 .

2

The l i m i t i n g value f o r ~ / h i s t h u s probably between 250 and 2

300 I b / i n

.

T h i s i n d i c a t e s a s shown i n Fig. 3 , t h a t d u r i n g t h e e a r l y p a r t of t h e season, when t h e e f f e c t i v e i c e cover i s

l e s s t h a n 20 i n . , t h e r e s e r v e of s t r e n g t h i n t h e cover i s

o f t e n l e s s t h a n 100 p e r c e n t of t h e a p p l i e d load. A s t h e season p r o g r e s s e s , t h e s i t u a t i o n improves. When t h e i c e t h i c k n e s s

i s 25 i n . o r g r e a t e r , t h e r e s e r v e of s t r e n g t h i s o f t e n 200 t o 300 p e r c e n t of t h e average l o a d b e i n g placed on t h e cover.

The way i n which companies have n a t u r a l l y t a k e n advantage of t h i s f a c t i n p r a c t i c e i s shown i n Fig. 4 where

t h e i n t e n s i t y of -the t r a f f i c g r a d u a l l y i n c r e a s e s w i t h i n c r e a s i n g

2

t h i c k n e s s ( o r t h e e q u i v a l e n t , d e c r e a s i n g ?/h ) s o t h a t most of t h e wood i s placed on t h e i c e when t h e r e i s a comfortable margin of s a f e t y . This f a c t i s r e f l e c t e d i n t h e breakthrough o b s e r v a t i o n s where t h e m a j o r i t y of f a i l u r e s occur f o r i c e t h i c k n e s s l e s s t h a n 20 i n . , whereas most of t h e wood i s

placed. on t h e i c e when t h e t h i c h e s s i s g r e a t e r t h a n 20 i n . ( F i g . 4 ) .

Although many i c e f a i l u r e s occur f o r i c e l o a d i n g s t h a t a r e q u i t e normal, t h e s t u d i e s i n d i c a t e thal; t h e y a r e confined p r i m a r i l y t o t h e c o n s t r u c t i o n period of t h e l a n d i n g

( F i g . 4 ) . This s u g g e s t s t h a t t h e i c e cover i s more s e n s i t i v e t o t h e a d d i t i o n a l f a c t o r s t h a t c o n t r i b u t e t o breakthroughs

when i t s t h i c l m e s s i s l e s s t h a n 20 i n . S t r e s s i n g and , r ~ k i n g of t h e i c e by n a t u r a l l y o c c u r r i n g temperature changes wculd

produce such behaviour. CONCLUSIONS

The s t u d y on t h e l o a d s placed s u c c e s s f u l l y on i c e covers by pulp and paper companies show t h a t f a c t o r s o t h e r

t h a n i c e t h i c k n e s s must be r e s p o n s i b l e f o r many of t h e f a i l u r e s o c c u r r i n g d u r i n g normal o p e r a t i o n s on i c e landings. Break- through o b s e r v a t i o n s i n d i c a t e t h a t t h e s e a d d i t i o n a l f a c t o r s a r e probably

-

(1) v e h i c l e speed;

( 2 ) c r a c k formation and t h e development of thermal s t r e s s e s by n a t u r a l l y o c c u r r i n g temperature changes ;

( 3 ) f a t i g u e of t h e i c e cover through r e p e t i t i v e l o a d i n g ; ( 4 ) formation of m u l t i p l e i c e l a y e r s s e p a r a t e d by a i r o r

water pockets; and

( 5 )

e r o s i o n o r b r i d g i n g of t h e i c e cover n e a r t h e shore. The m a j o r i t y of f a i l u r e s r e p o r t e d occur f o r i c e t h i c l m e s s e s l e s s t h a n 20 i n . , For t h e s e t h i c k n e s s e s , t h e i c e l o a d i n g f o r t h e y e a r i s g r e a t e s t and t h e i c e cover i s l i k e l y most s e n s i t i v e t o temperature changes. Most of t h e wood i s placed on t h e

l a n d i n g s when t h e i c e t h i c k n e s s is g r e a t e r t h a n 20 i n . By

g i v i n g c a r e f u l a t t e n t i o n t o t h e f a c t o r s l i s t e d above, it should be p o s s i b l e t o reduce t h e frequency of occurrence of v e h i c l e breakthroughs without reducing t h e average weight of t h e l o a d s now placed on i c e covers. I n some c a s e s , it should be p o s s i b l e t o i n c r e a s e t h i s average weight.

ACKNOWLEDGMENTS

The a u t h o r i s indebted t o t h e f o l l o w i n g pulp and paper companies f o r t h e i r c o n t r i b u t i o n t o t h i s s t u d y on t h e use of i c e l a n d i n g s : A b i t i b i , Canadian I n t e r n a t i o n a l Paper,

C o n s o l i d a t e d P a p e r , Donacona Paper, Dryden Paper, Great Lakes P a p e r , Huron F o r e s t P r o d u c t s , K.V. P., P r i c e B r o t h e r s , S t . Lawrence Corp., and Spruce F a l l s Power and Paper. He would l i k e t o e x p r e s s h i s s i n c e r e t h a n k s t o t h e i n d i v i d u a l s i n t h e s e companies who made and r e c o r d e d t h e o b s e r v a t i o n s . The a u t h o r w i s h e s a l s o t o acknowledge t h e v e r y c o n s i d e r a b l e c o - o p e r a t i o n and a s s i s t a n c e r e c e i v e d from t h e Canadian P u l p and P a p e r

A s s o c i a t i o n i n e s t a b l i s h i n g and c o n d u c t i n g t h e s t u d i e s on t h e b r e a k t h r o u g h of v e h i c l e s and t h e use of i c e l a n d i n g s ,

REFERENCES

(1) Gold, L. W. F i e l d s t u d y on t h e l o a d b e a r i n g c a p a c i t y of i c e c o v e r s . Woodlands Rev., P u l p and R i p e r Mag. of Canada, Vol. 6 1 , ( 5 ) , May 1960, p.

11-15.

( 2 ) Rose, L. B. and C. R. S i l v e r s i d e s . The p r e p a r a t i o n o f

i c e l a n d i n g s by p u l p and p a p e r companies i n e a s t e r n Canada. Trans. Ehg. I n s t , Can., V o l . 2 ( 3 ) , 1958, p. 101-107.

( 3 ) Meyerhof, G. G. B e a r i n g C a p a c i t y of f l o a t i n g i c e s h e e t s . Proc. Am. .Sot. C i v i l Ehg., J o u r . Eng..Mech. Div.,

EM-5, October 1960, p. 113-145.

( 4 )

Gold, L. W. D i s c u s s i o n t o "Bearing c a p a c i t y of f l o a t i n g i c e s h e e t s " , b y G. G. Meyerhof, Proc. Am. Soc. C i v i l Eng., J o u r . Xng, Mech. Div., EM-2, P a r t 1, A p r i l 1961, P O 8 3 .

( 5 )

B u t k o v i t c h , T. R. U l t i m a t e s t r e n g t h of i c e . Research

P a p e r No. 11, Snow, I c e and Permafrost Research E s t .

,

Wilmette, I l l . , 1954.

- 8 -

TABLE I

WEIGHT OF

WOOD

AND b W E R

OF

TRIPS

ON LANDING

TABLE I1

WEIGHT OF WOOD

AND NUMBER OP

TRIPS ON

LANDING

Approximate a r e a covered w i t h wood

115

544

22.6

8.4

48

39

16

14

8

30

110

97

Approximate weight ( t o n s )

166,364

168,341

10,861

760

71,184

37,250

12,810

14,443

5,569

28,113

113,765

78,288

707,748

Number of t r u c k t r i p s 8

577

10,193

1,045

171

4,136

2

,

493

872

1,121

36

5

3,003

7,411

3,522

42 909

Average weight wood p e r t r i p ( t o n s )

19.4

16.5

10.4

4

5

17.2

14.9

14.7

12.9

15

3

9-4

15.4

22.2 Approximate a r e a covered w i t h wood

27

29

17

38

28

32

-

Approximate weight ( t o n s )

25,500

29,100

20,600

22,700

28,200

24,800

150,900

Number of t r u c k t r i p s

3,550

3,594

3,754

3,076

3,569

3,896

21,439

Average weight wood p e r t r i p ( t o n s )

7.2

8.1

5.5

7.4

7.9

6.4

Report en t h s Uso of Ice ?,anAings

N ~ m o of

Cornl?nny R i v e r o r 1 3 ke

--

T o t a l a x of landing ~ Acres.

Gross a r e a or' l a n d i n g covered wi.th l o g s a t l a s t d a t e Acres. ~ e a m r k s ( 1 f lo a d s g i v e n i n c o r d s , g i v e average weight of 1. cord.)

T h i s form when completed t o be r e t u r n e d t o

-

S e c r e t a r y ,

Su3committee on Snow and I c e ,

A s s c c i a t e Committee on S o i l and S n m Mechanics,

IIa t i o n a l Research Council, Ottawa, Ontario.

n 3 t a

-

-

FIGURE 1. FORM USED T O

REPORT THE

USE O F I C E LANDINGS

Pdle~ris of

--

-Li*arloport i e . 2 0 l o a d s h o r s e p l u s s l e i g h ,

l h

loads !J t o n t r u c k loreight of 1 z g e s - t ; lonc! f o r d a y ( v e h i c l 1 3 p l u s l.o.jci, l b s . )

-

--

--

--

-

--

-

-

----

--

1 Tcs t h i c k - T o t a l No. of l o a d s

---

---- ness #-a "lot.31 f o r d a y

-

Ycight of wood o r No. of cords

-

i n .

-

?fl~tlil.oc

1 2 3 4 6 8 10 20 30 40 60 80 100

EFFECTIVE ICE THICKNESS h , INCHES

FIGURE

2

AVERAGE LOAD

FOR GIVEN EFFECTIVE ICE

EFFECTIVE ICE THICKNESS h , INCHES 5 2 0 4 8 0 4 4 0 4 0 0 3 6 0 3 2 0 2 8 0 - - 2 4 0 2 0 0 - 1 6 0 - 1 2 0 8 0 4 0 Oo

FIGURE

3

OBSERVED LOADING AT G I V E N THICKNESS OF T H E

ICE COVER,

P

IN L B ,

h IN INCHES

Y 1 I !

X X Y x -

X

-

- _{AVERAGE LOAD P OBTAINED F R O M U S E}

- - OF ICE LANDING S U R V E Y -~ x L O A D P f , , l OBTAINED F R O M BREAKTHROUGH R E P O R T S -. - x -

. \

- - - x -- 0 - -- - -

-- _{CURVE FOR P = 2 0 TONS -}

x - x - -. -- - - X X -- I x - X - -. I: x X X X - - X - x - X - X X - X -

. .

X

.

- - * * . . I 5 10 15 2 0 2 5 3 0 ' 3 5 4 0

10 2 0 3 0 4 0

E F F E C T I V E ICE THICKNESS h, INCHES

I I - _[3 SHADED OBSERVATIONS - OCCURRED IN USE OF - ICE SURVEY - - - FIGURE 4

NUMBER OF LOADS PLACED ON ICE AND NUMBER O F

BREAKTHROUGHS FOR EFFECTIVE ICE THICKNESSES IN STEPS

FIGURE 5

MAXIMUM LOADING OF ICE COVERS FOR E A C H AVERAGE LOADING,

P

AND Pm IN L B , h IN INCHES