D I A G R A M FOR D I V I D I N G S O I L S I N T O ORDINARY,

S L U M P I N G , AND S W E L L I N G

(UDC 624.131.2)

A. I. Danilov

Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, p. 26, September-October, 1964

According to SNiP I I -BJ -62, paragraph 2.9, slumping soils include clays having a water content G -< 0.6 at a value of

% ~ EL - - > ~ - - 0 . I ,

1 + % (1)

where % is the void rat io of an undisturbed sample and natural water content; e L is the void ratio of the same

sample corresponding to the water content at the liquid l imi t WL.

Swelling soils include clays for which the value

So--" % I + % < - - 0 . 4 . (2)

As is known

~o = xosk (3)

and

"(p llf L

~L = %'w (4)

where 7- is the specific gravity of particles; )~k is the bulk specific gravity of the skeleton; 7w is the specific ia gravity of water.

Substituting s0 and e L from (3) and (4) into formulas (1) and (2), after transformations we obtain the new ex -

pressions which are convenient for compil ing the diagrams:

for slumping soils

1 w L >--o.l. ( r ) ~p ~p

for swelling soils

< - - 0 . 4 ~p ~w

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85-

\\~ ~ > \ \ \ ,\\\ \m,,\\\\

N ~ . \ , .',- \ \ ~ M

,,o,, ,.20 ,.~0 ~so ,~0 2.o~

Graphs plot ted by formulas (1 ') and (2 ' ) . 1) Swelling soils for W 0 < Wsw

% - ~L % -- eL and - - <--0.4: ; 2) ordinary for ~ - - , from 0,1 to 0.4;

1 4- ~,. 1 + e o

eo - e L 3) slumping for O - 0.6 and > - o.~

I -l-So

From formulas (i') and (2') we plot the diagrams (figure). Both formulas, depending on the numerical values

of the specific gravity yp, yield a family of curves.

All curves of the lower family , plot ted from formula (1 ') , correspond to the condit ion EO -- SL

l -}-% . . . . 0.1

and below these curves 1 -f-%

> - - 0 . 1 .

All curves of the upper family, plot ted from formula (20 correspond to the condit ion % - eL

1 + % -- - - 0 . 4 ,

and above them so--~L < - - 0 , 4 . 1 + %

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At any point between the curves of both families with identical specific gravities the value of the expression

,., gO - - ~ , - - will vary from --O.1 to -0 .4 . Thus, in the figure the curves of these two families having the same

1 + %

specific gravities )/p mark off three zones of soil: slumping, ordinary, and swelling.

According to the recommendations of the Institute of Foundation Beds ("Technical Specifications for Designing

Foundation Beds of Structures on Swelling Soils," Gosstroiizdat, 1963) the criterion for ~%'-- %-- is not taken as 1 +~0

- 0 . 4 but as - 0 . 3 . Therefore the dashed line on the diagram depicts the boundary between ordinary and swelling soils at a criterion of - 0 . 3 for the same values of specific gravities 2.5-2.8.

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