Unfrozen water in frozen soils: a selective review of the literature

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Unfrozen water in frozen soils: a selective review of the literature

NATIONAL RESEARCH COUNCIL CANADA

DIVISION OF BUILDING RESEARCH

UNFROZEN WATER I N FROZEN SOILS: A SEL;ECTIE REVIEW OF !WE LITERATURE

b y P. J . W i l l i a m s I n t e r n a l R e p o r t No. 2 0 9 of t h e D i v i s i o n of B u i l d i n g R e s e a r c h OTTAWA November 1960

A h o w l e d g e of t h e e x t e n t t o which t h e w a t e r c o n t e n t of s o i l s may be f r o z e n a t any given t e m p e r a t u r e below t h e f r e e z i n g p o i n t of w a t e r under normal c o n d i t i o n s t u r n s

o u t t o be of c o n s i d e r a b l e importance i n t h e development of f r o z e n ground technology. S t r e n g t h p r o p e r t i e s of f r o z e n ground may w e l l be a f f e c t e d , a t l e a s t w i t h i n c e r t a i n r a n g e s of c o n d i t i o n s , by t h e unfrozen w a t e r c o n t e n t . Also, i n view o f t h e r e l a t i v e l y l a r g e amounts o f h e a t i n v o l v e d i n t h e

l a t e n t h e a t of f u s i o n , i n s u f f i c i e n t i n f o m a t i o n a b o u t t h e p r o p o r t i o n o f t h e w a t e r c o n t e n t which i s f r o z e n a t any g i v e n c o n d i t i o n can l e a d t o s e r i o u s e r r o r s i n h e a t t r a n s f e r and h e a t balance c a l c u l a t i o n s f o r t h e ground. !lhe a u t h o r who i s a r e s e a r c h o f f i c e r w i t h t h e Snow and I c e . S e c t i o n of t h e D i v i s i o n i s p r e s e n t l y engaged i n s t u d i e s of t h e f r e e z i n g of s o i l w a t e r , a n d a s a f i r s t s t e p h a s produced t h i s review of t h e l i t e r a t u r e which i s now r e p o r t e d . Ottawa November 1960 A s s i s t a n t D i r e c t o r N. B. Hutcheon

UTill'liOZkiN WATER I F PIIOZEIT SOILS :

A SLLLCTIVE: REVIEIV 03' DIE LI'JJ3RATTJRX

by P. J . \ V i l l i a m s I t h a s l o n g b e e n known t h a t t h e f r e e z i n g p o i n t o f f i n e - g r a i n e d s o i l s l i e s below O ° C . P e t i t ( 1 8 9 7 ) showed by l a b o r a t o r y e x p e r i m e n t s t h a t t h e f r e e z i n l ; p o i n t v a r i e d w i t h s o i l t y p e , a n d r e l a t e d t h i s t o t h e s u r f a c e f o r c e s o f t h e p a r t i c l e s . H o l m q u i s t ( 1 8 9 7 ) o b s e r v e d i n t h e f i e l d , b e t w e e n i c e l e n s e s , c l a y l a y e r s which were s t i l l p l a s t i c a t a

t e m p e r a t u r e o f -4OC t o -5OC. Hamberg ( 1 9 1 5 ) a t t r i b u t e d t h i s phenomenon t o a t r u e f r e e z i n g p o i n t d e p r e s s i o n due t o t h e s o i l s o l u t e s a n d c o l l o i d a l e f f e c t s , a n d n o t t o s u p e r c o o l i n g . Bouyoucos ( 1 9 1 6 - 2 1 ) i n h i s e a r l i e r i n v e s t i g a t i o n s a l s o m e a s u r e d t h e f r e e z i n g p o i n t d e p r e s s i o n o f v a r i o u s s o i l s . H i s p r o c e d u r e gave a s i n g l e v a l u e f o r t h e f r e e z i n g p o i n t f o r e a c h s o i l t e s t e d . lZle u n c e r t a i n s i g n i f i c a n c e o f s u c h a p o i n t d e t e r m i n a t i o n was d e m o n s t r a t e d by h i s own s u b s e q u e n t e x p e r i m e n t s on volume c h a n g e s i n t h e s o i l p o r e s . Wi-th a d i l a t o m e t e r a p p a r a t u s h e showed t h e p r o g r e s s i v e f r e e z i n g o f t h e s o i l m o i s t u r e , by o b s e r v a t i o n s at -1.5OC, -4OC, a n d -78OC

(Bouyoucos 1 9 1 7 ) . He e m p h a s i z e d t h e i m p o r t a n c e o f a d s o r p t i o n l a y e r s a r o u n d t h e s o i l p a r t i c l e s , a l t h o u g h much o f h i s r e a s o n i n g a p p e a r e d s u b s e q u e n t l y i n c o r r e c t . Bouyoucos w a s p r o b a b l y t h e f i r s t t o p o i n t o u t t h a t f r e e z i n g a n d t h a w i n g p r o d u c e c h a n g e s w i t h i n a s a m p l e , s u c h t h a t d i f f e r e n t v a l u e s f o r t h e u n f r o z e n w a t e r c o n t e n t a r e o b t a i ~ e d i n s u b s e q u e n t t e s t s u n d e r o t h e r w i s e s i m i l a r c o n d i t i o n s . J u n g ( 1 9 3 2 ) o b s e r v e d m i c r o s c o p i c a l l y t h e s o i l f r e e z i n g p r o c e s s u n d e r v a r i o u s t h e r m a l c o n d i t i o n s . The grovith o f i c e c r y s t a l s i n t h e p o r e w a t e r f u r t h e s t f r o m t h e p a r - b i c l e s w a s f o l l o w e d by s o l i d i f i c a t i o n o f t h e " s o i l g e l " m a t e r i a l , a n d h e t h o u g h t t h a t t h e r a i s e d p r e s s u r e due t o t h e a d s o r p t i o n f o r c e s r e s u l t e d i n a f r e e z i n g p o i n t d e p r e s s i o n . lZle n a t u r e o f t h e f r e e z i n g p r o c e s s ( s h a p e o f c r y s t a l s , e t c . ) d e p e n d e d on r a t e o f f r e e z i n g , w a t e r c o n t e n t , a n d s p e c i f i c s u r f a c e . J u n g w a s a p p a r e n t l y t h e f i r s t t o o b t a i n n u m e r i c a l v a l u e s f o r t h e amount o f u n f r o z e n w a t e r a t v a r i o u s n e g a t i v e t e m p e r a t u r e s , u s i n g f o r t h i s a d i l a t o m e t e r method. F o r m o i s t c l a y s o i l s h e r e p o r t e d , f o r example, 1 9 p e r c e n t u n f r o z e n w a t e r w e i p h t o f u n f r o z e n v i a t e r ) a t ( i . e . _{w e i g h t o f d r y s o i l}

---

-Z°C, a n d 1 0 per. c e n t a t v i e i ~ h t o f w a t e r

---

- l O ° C , when _{t h e t o t a l w a t e r c o n t e n t ( i . e .}

=&kdry

_soil

I

was a b o u t

33

p e r c e n t . These v a l u e s , i n spite o f u n c e r t a i n t i e s i n t h e u s e of t h e d i l a t o m e t e r me-thod, a r e s i m i l a r t o many

Beskow ( 1 9 3 5 ) o b t a i n e d v a l u e s f o r t h e u n f r o z e n w a t e r c o n t e n t f o r v a r i o u s s o i l s , a s a f u n c t i o n o f t e m p e r a t u r e and m o i s t u r e c o n t e n t , from t i m e - t e m p e r a t u r e c u r v e s f o r t h a w i n g a n d f r e e z i n g c y c l e s . Using pure f r a c t i o n s a n d d e t e r m i n i n g t h e f r e e z i n g p o i n t ( a t which most o f t h e w a t e r f r o z e ) he o b t a i n e d v a l u e s o f t h e f r e e z i n g p o i n t d e p r e s s i o n a s a f u n c t i o n o f g r a i n ( a n d p o r e ) s i z e . B e l i e v i n g t h e f r e e z i n g p o i n t d e p r e s s i o n t o b e due t o t h e a d s o r p t i o n f o r c e s , a n d e x t r a p o l a t i n g t h e g r a i n - s i z e f r e e z i n g p o i n t d e p r e s s i o n c u r v e s h e o b t a i n c d a v a l u e o f a t l e a s t 4 0 p f o r t h e d i s t a n c e from t h e p a r t i c l e s u r f a c e a t which a d s o r p t i o n f o r c e s a r e s t i l l a p p r e c i a b l e . However, s u p e r c o o l i n g a n d o t h e r u n c e r - L a i n t i e s p r o b a b l y a f f e c t e d h i s r e s u l t s . Winterkorn ( 1 9 4 3 ) d i s c u s s e d t h e r a i s e d p r e s s u r e s w i t h i n t h e a d s o r b e d w a t e r , i n r e l a t i o n t o t h e Tamann-

Bridgeman phase diagram (Tamann a n d b'lehl, 1 9 2 5 , p. 1 5 8 - 1 7 1 ) . According t o t h e p h a s e d i a g r a m , l i q u i d w a t e r c a n n o t e x i s t i n a s t a b l e form below -2Z°C, a n d a t t h i s t e m p e r a t u r e o n l y a t

p r e s s u r e s of 2250 kg/sq cm. Depending on t h e p r e s s u r e , l i q u i d w a t e r may e x i s t i n a s t a b l e form a t t e m p e r a t u r e s between -2Z°C a n d O°C. The most f i r m l y a d s o r b e d w a t e r

( t h e r e f o r e u n d e r t h e h i g h e s t p r e s s u r e s ) i s i n t h e s o l i d form ( i c e V I ) a t above O°C. The a p p l i c a b i l i t y o f t h i s a p p r o a c h seems q u e s t i o n a b l e b e c a u s e o f t h e c o m p l e x i t y of t h e s o i l - w a t e r s y s t e m a n d t h e r o l e o f d i s s o l v e d s a l t s a n d e s p e c i a l l y c a t i o n s , i n t h e a d s o r p t i o n phenomena ( e . g . P r u t t o n a n d Maron 1 9 5 1 , N e r s e s o v a 1 9 5 7 ) . T s y t o v i c h ( 1 3 1 7 ) summarized some of t h e l i t e r a t u r e ( p a l - t i c u l a r l y R u s s i a n ) a n d c i t e s c a l o r i n l e t r i c d e t e r m i n a t i o n s of u n f r o z e n w a t e r c o n t e n t . He s t r e s s e s t h e i m p o r t a n c e of t h e u n f r o z e n w a t e r c o n t e n t , a n d t h e f a c t o r s c o n t r o l l i n g i t ,

i n

c o n s i d e r a t i o n o f b o t h t h e r m a l a n d m e c h a n i c a l p r o p e r t i e s of f r o z e n ground. P u b l i c a t i o n s of t h e F r o s t S t u d i e s I n s t i t u t e ( I n s t i t u t M e r z l o t o v e d e n i i a

,

1953-57 )

,

i n R u s s i a , h a v e d e s c r i b e d a p p a r a t u s f o r c a l o r i m e t r i c d e t e r m i n a t i o n s o f u n f r o z e n w a t e r c o n t e n t ( e . g . Nersesova 1 9 5 4 , 1 9 5 7 ) . S u f f i c i e n t p o i n t d e t e r m i n a t i o n s a l l o w e d t h e drawing o f g r a p h s showing u n f r o z e n w a t e r c o n t e n t a s a f u n c t i o n o f t e m p e r a t u r e . F o r c l a y s o i l , a s h i g h a s 34.2 p e r c e n t u n f r o z e n w a t e r c o n t e n t was measured a t -0.5OC a n d 1 4 . 8 p e r c e n t at- -50°C. According t o T s y t o v i c h

( 1 9 5 4 ) t h e u n f r o z e n w a t e r c o n t e n t f o r g i v e n c o n d i t i o n s i s n o t a f f e c t e d by v a r i a t i o n s i n t o t a l m o i s t u r e c o n t e n t s o l o n g a s t h e s o i l i s s a t u r a t e d . Using s i m i l a r m a t e r i a l , t h e e f f e c t s o f t e m p e r a t u r e a n d p r e s s u r e have b e e n d i s c u s s e d by Nersesova a n d T s y t o v i c (1954-57) a n d a l s o by Love11 ( 1 9 5 7 ) . Applying a l o a d of 2 kg/cm9 t o a s a n d y - c l a y specimen r a i s e d t h e u n f r o z e n w a t e r c o n t e n t from

1 0 . 6 t o 14.52 p e r c e n t , a t a t e m p e r a t u r e o f -l.7OC, when t h e t o t a l m o i s t u r e c o n t e n t was 25 p e r c e n t . A t l o w e r t e m p e r a t u r e s t h e e f f e c t s o f p r e s s u r e a r e l e s s marked.

E x p e r i m e n t s i n d i c a t e t h e s i g n i f i c a n c e of exchange

c a t i o n s a t t e m p e r a t u r e s between O°C a n d -2OC ( N e r s e s o v a 1 9 5 7 ) . !he work o f Grigarleva ( 1 9 5 7 ) i n d i c a t e d t h a t c a p i l l a r y e f f e c t s i n f r e e z i n g p o i n t d e p r e s s i o n a r e l i m i t e d t o t e m p e r a t u r e s above -0.2OC w h i l e t h e e f f e c t s o f i o n s i n t h e d i f f u s e l a y e r a r e

s i g n i f i c a n t a t t e m p e r a t u r e s down t o -0.6OC. These a n d

s i m i l a r p h y s i c o - c h e m i c a l e f f e c t s a r e d i s c u s s e d by Nersesova a n d Tyutyanov ( 1 9 5 7 ) , who a l s o c i t e o b s e r v a t i o n s o f t h e d e c r e a s e i n d i s p e r s i o n which o c c u r s when c l a y s a r e f r o z e n . S t r e n g t h u n d e r v a r i o u s c o n d i t i o n s o f t e m p e r a t u r e a n d p r e s s u r e i s r e l a t e d t o phase c o m p o s i t i o n , a c c o r d i n g t o t h e e x p e r i m e n t s a n d f i e l d s t u d i e s of Vialov ( 1 9 5 5 ) . Phase c h a n g e s s h o u l d be c o n s i d e r e d a f u n d a m e n t a l p r o c e s s ' i n d e f o r m a t i o n a n d f a i l u r e o f f r o z e n ground u n d e r l o a d . The m o b i l i t y a n d d i s t r i b u t i o n o f t h e u n f r o z e n w a t e r c o n t e n t a n d t h e s t r e s s e s w i t h i n i t a r e i m p o r t a n t a l s o b u t a r e n o t e a s i l y r e l a t e d t o t h e q u a n t i t y o f t h e u n f r o z e n w a t e r d e t e r m i n e d c a l o r i m e t r i c a l l y . C a l o r i m e t r i c methods seem r e a s o n a b l y s u i t a b l e f o r o b t a i n i n g i n f o r m a t i o n t o be u s e d f o r t h e r m a l c o n s i d e r a t i o n s i n f i e l d problems ( a s i n c a l c u l a t i o n s o f f r o s t p e n e t r a t i o n , e.g. Luk'ianov and Golovko 1957 ) . O t h e r a n d more p r e c i s e t e c h n i q u e s o f i n v e s t i g a t i o n o f t h e amount a n d b e h a v i o u r o f u n f r o z e n w a t e r may be r e q u i r e d i n l a b o r a t o r y s t u d i e s o f t h e mechanics o f f r o z e n ground. It i s c o n c l u d e d t h a t i n s p i t e of t h e d e m o n s t r a t e d magnitude a n d s i g n i f i c a n c e of t h e u n f r o z e n w a t e r c o n t e n t of f r o z e n s o i l s , o n l y a rough e s t i m a t e o f t h e amount p r e s e n t u n d e r a p a r t i c u l a r s e t of f i e l d c o n d i t i o n s , a n d o f i t s i n f l u e n c e on t h e s t r e n g t h a n d t h e r m a l c h a r a c t e r i s t i c s o f t h e a s s o c i a t e d s o i l ,

i s

a t p r e s e n t p o s s i b l e .

- 4 - R e f e r e n c e s R e f e r e n c e s marked w i t h a n a s t e r i s l c ( % ) a r e s i g n i f i c a n t b i b l i o g r a p h i e s c o n c e r n i n g u n f r o z e n w a t e r c o n t e n t . 1. Beskow, G. 1935. S o i l f r e e z i n g a n d f r o s t h e a v i n g w i t h s p e c i a l a p p l i c a t i o n t o r o a d s a n d r a i l r o a d s . Trans- l a t e d by N. Western, Technol. I n s t . E v a n s t o n , 1 9 4 7 , from t h e Swedish p u b l i c a t i o n S v e r . Geol. U n d e r s . , S e r . C , 375.

2. Bouyoucos, G . J . a n d M.M. McCool. 1916. F u r t h e r s t u d i e s on t h e f r e e z i n g p o i n t l o w e r i n g of s o i l s . Pfiich. A g r i c . C o l l . Exp. S t . , Tech. B u l l . No. 31, 51p.

3. Bouyoucos, G. J. 1917. C l a s s i f i c a t i o n a n d measurement of t h e d i f f e r e n t f o r m s of w a t e r i n t h e s o i l by means of t h e d i l a t o m e t e r method. Mich. A g r i c . C o l l . Exp. S t . , Tech. B u l l . No. 3 6 , 48p.

4.

Bouyoucos, G . J . 1921. A new c l a s s i f i c a t i o n o f t h e s o i l m o i s t u r e . S o i l S c i e n c e , Vol. 9 , No. 1.

5.9

G r i g o r t e v a , V. G. 1957. 0 _{p o n i z h e n i i t e m p e r a t u r y z a m e r z a n i i a}

vody v d i s p e r s n y k h g r u n t a k h . Akademiia Nauk SSSR,

I n s t i t u t M e r z l o t o v e d e n i i a i m . V.A. Obrucheva, f i k t e r i a l y po l a b o r a t o r n y m i s s l e d o v a n i i a m merzlylch g r u n t o v ,

S b o r n i k 2 , p. 5-15.

6. Hamberg, Axel. 1915. Z u r K e n n t n i s d e r vorg;nge i n

Grdboden beim G e f r i e r e n und A u f t a u e n sowie Bemerkungen u b e r d i s e r s t e K k i s t a l l i s a t i o n d e s LTses i n Virasser. Geol. For. Forh. Bd. 37, H. 5.

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7 . H o l m q u i s t , P. J. 1896-97. Uber machanische ~ t b l r u n ~ e n und chemische Umsetzungen i n dem B a n d e r t h o n Schwedens. B u l l . Geol. I n s t . Univ. U p s a l a , Vol. 3 , No. 1 2 .

8.* _{I n s t i t u t M e r z l o t o v e d e n i i a}

.

_{1953-57. M a t e r i a l y po}

l a b o r a t o r n y m i s s l e d o v a n i i a m merzlykh g r u n t o v .

Akademiia Nauk SSSR, I z d . Moskva, i m . V.R. Obrucheva, S b o r n i k 1 , 2 , 3 .

9. J u n g , E. 1932. W e i t e r e r B e i t r a g z u r a g g r e g i e r e n d e n Einwirkung d e s F r o s t e s a u f den Ekdboden. Z e i t s c h r .

f u r

P f l a n z e n e r n . Wng.

u .

Bodenk. A , Viiss. T e i l , Bd. p. 1-20.

1 0 . L o v e l l , C.W. 1957. Temperature e f f e c t s on p h a s e c o m p o s i t i o n a n d s t r e n g t h of p a r t i a l l y - f r o z e n s o i l . Highway R e s e a r c h Board, B u l l . 1 6 8 .

L u k t i a n o v , V.S. a n d M.D. Golovko. 1957. R a s c h e t

g l u b i n y p r o m e r z a n i i a g r u n t o v

.

Koskva

,

Gos

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