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Proceedings of the Sixteenth Canadian Soil Mechanics Conference 12-

13-14 September 1962: Technical Memorandum No. 82Crawford, C. B.; Hamilton, J. J.

NATIONAL RESEARCH COUNCIL O F CANADA

ASSQCIATE COMMITTEE ON SOIL AND SNOW MECHANTGS

PROCEEDINGS

O F T H E

SIXTEENTH CANADIAN SOIL MECHANICS C O N F E R E N C E

12- 13-14 S E P T E M E E R 1962

TECHNICAL MEMORANDUM NO. 8 2

P r e p a r e d b y

E. P e n n e r a n d M i s s J. B u t l e r

OTTAWA JANUARY 19 64

PREFACE

The Sixteenth Soi l Mechanics Conference held in September 1962 a t the Universi ty of A lber ta , under the cha i rmanship of Dr . R. M. Hardy , was sponsored jointly by the EIC and the Assoc ia te Commit tee on Soi l and Snow Mechanics of the National Resea rch Council. Although the conference shared some of the sess ions with the Zone "A" Technical Meeting, these proceedings re.zord only the f i r s t two days of the three-day conference which were devoted to topics of i n te res t to so i l engineers. The proceedings contain s u m m a r i e s of those pape rs which a r e to be publ ished by journals; the re.naining pape rs , which a r e not expected to appear e lsewhere in the i r p resen t f o r m , a r e pr inted in the i r ent i rety.

Nineteen hundred and sixty-two was the last year in which the ACSSM, through i t s Subcommit tee on Soi l Mechanics, was responsib le f o r the organizat ion and s p ~ n s o r s h i p of the Annual Soi l Mechanics Conference. The Seventeenth Conference wi l l be held in 1963 in Ottawa in Se?tember , but i t wi l l be under the ausp ices of the EIC.

The need f o r such a "meet ing ground1' , a s these annual conferences have provided for so i l mechanics wo rke rs in a l l p a r t s of Canada, was f i r s t apprec ia ted in the immed ia te post-war per iod by R. F. Legget, Chai rman of the Assoc ia te Commit tee on Soi l and Snow Mechanics, then on the civi l engineer ing staff of the Univers i ty of Toronto. The f i r s t meet ing was held in Ottawa in Apr i l 1947 and was attended by a l l the known Canadian wo rke rs in the f ie ld a t that t ime , with D r . L. F. Cooling (of the Br i t i sh Building Resea rch Stat ion) a s an honoured guest .

The Division of Building Resea rch was establ ished by the National Research Council la ter in 1947. Star t ing in 1948, meAmbers o: the staff of the Soi l Mechanics Sect ion of the Division have c a r r i e d the admin is t ra t ive responsib i l i ty f o r the organizat ion of the success ive conferences, in associat ion with local commi t tees when the meet ings were n,3t held in Ottawa, unti l the Sixteenth Conference of 1962.

At f i r s t , these gather ings se rved the needs of so i l mechanics r e s e a r c h wo rke rs in Canada, providing a useful f o rum for

d iscuss ion. F r o m the outset , the mee t ings w e r e cha rac te r i zed by the f ru i t fu l par t ic ipat ion of a few w o r k e r s f r o m the a l l ied d isc ip l ines of pedology and geology, with expe r t s f r o m other b ranches of appl ied sc ience often p resen t a l s o , f o r e s t r y w o r k e r s having m a d e usefu l cont r i - but ions. Mimeographed proceed ings w e r e p repa red annual ly by the DER Soi l Mechan ics staff not only to prov ide a usefu l pe rmanen t r e c o r d but a l s o to m a k e known the r e s u l t s of so i l mechan i cs r e s e a r c h fo r the benef i t of eng ineers engaged in foundat ion, road and a i r po r t

des ign and const ruc t ion . The conferences gradua l ly a t t rac ted the at tendance of such eng ineers and over the y e a r s a s s u m e d the cha rac te r of ful l - f ledged pro fess iona l mee t ings with a s many a s 250 eng ineers and sc ien t i s t s p resen t f r o m a l l ove r Canada. With the s u c c e s s of

the annual conferences a s s u r e d , the Assoc ia te Commi t tee decided that one of i t s in i t ia l goals had been a t ta ined and that the spz~nso rsh ip of the mee t ings had rea l ly ceased to be a p roper function f o r the National R e s e a r c h Council.

It was ag reed that the organ iz ing of such Large mee t ings could best be assumed by a n eng ineer ing soc ie ty such a s the Eng ineer ing Inst i tu te of Canada. The Inst i tu te welcomed the suggest ion .and es tab l ished a Geotechnical Engineer ing Division of i t s Commi t tee on Techn ica l Opera t ions to be respons ib le f o r fu tu re conferences. A g radua l t rans i t ion was a r r a n g e d , the Fi f teenth Conference being sponsored by the NRC and EIC, and the Sixteenth Conference under the ausp ices of the EIC an'd NRC. The t r ans fe r i s now comple te , p lans f o r the Seventeenth Conference a l r eady being p repa red by the Ge3technical Eng ineer ing Division of CTO/EIC.

It m a y be noted that al though many of the annual con fe rences w e r e held i n Ot tawa, a number w e r e held in va r ious o ther Locations such a s Vancouver , Le thbr idge, Edmonton, Saskatoon, Winnipeg, N iagara F a l l s , Mon t rea l , and Hal i fax , to b r ing the benef i ts of such mee t i ngs to those who could not t r ave l the Long d is tances involved. Nineteen hundred and sixth-two a l s o m a r k s the las t y e a r when the proceed ings o l the conference wi l l by publ ished b j the ACSSM. F o r this f ina l y e a r , those p a p e r s not appear ing e l sewhere in recognized journa ls wi l l be publ ished i n the proceed ings; o the rs wi l l be summar i zed .

T A E L E O F CONTENTS

P a g e -- Section 1 -

Sect ion 2 -

Sect ion 3 -

Sect ion 4 -

Sect ion 5 -

Sect ion 6 -

Sect ion 7 -

Section 8 -

Sect ion 9 -

Sect ion 10 -

Sect ion 11 -

Sect ion 12 -

Shear St rength of a Remoulded Normal ly Consol idated Homionic Clay by S. Thornson.

The Eng ineer ing P r o p e r t i e s of I l l i te Re1ate.d to F a b r i c and P o r e Wa te r Composi t ion by R. M. Quigley. 2 1

Measu remen t of Shear St rength , P las t i c i t y and Wate r Retent ion of C lays Re la ted to In te rpa r t i c le F o r c e s by B. P . Warkent in. 43

S u m m a r y of Heave of Spi l lway S t ruc tu res on Clay Sha les by R. P e t e r s o n and N. P e t e r s .

5 9 S u m m a r y of Volume Changes i n Undisturbed Clay P ro f i l e s i n Wes te rn Canada by J. J. Hami l ton. 6 3

S u m m a r y of P r a c t i c a l Exper ience with Highly Swel l ing Soi l Types by R. M. Hardy and A. 0. Dyregrov . 6 1

S u m m a r y of Phys ico- Chemica l Phenomena in Soi l Ma te r i a l s by S. Pawluk. 62

S u m m a r y of Super f ic ia l Deposi ts of A lbe r ta by C. P. Gravenor and L . A. Eay rock . 63

Summary of Eng ineer ing Aspec ts of the G rea t Slave Rai lway by J. L. C h a r l e s , V. R . Cox and F. L. Peckove r . 6 4

S u m m a r y of P r e l i m i n a r y Soi l Mechan ics Aspec ts of the Red R ive r Floodway by J. Mishtak. 65

S u m m a r y of The Mica C r e e k P r o j e c t - Foundat ions and Ma te r i a l Invest igat ion by W. P. Har land. 66

S u m m a r y of Foundat ion T rea tmen t and Const ruc t ion of Six teen Mi les of Dyke a t Manitoba Hyd ro ' s Grand Rapids P r o j e c t by A. Koropatn ick, W. S. I som and J. R. Ret t ie .

PROGRAM

of the Engineering Inst i tute of Canada Zone "A" Technical Conference

in Conjunction with The Sixteenth Annual Canadian

Soil Mechanics Conference Edmonton, A lber ta , September 12-13- 14, 1962

Wednesdav, 12 September 1962

Registrat ion

Opening Remarks - Dr. R. M. Hardy, Conference Chai rman. M r . C. B. Crawford, National Resea rch Council.

TECHNIGAL SESSION #l

"Volume Change Charac te r i s t i cs of Highly P las t i c So i l s f t C. B. Crawford, Chai rman

"Volume Changes in Undisturbed Clay Pro f i l es in We s te rn Canadat ' J. J . Hamil ton, N. R. C.

"Heave of Spillway S t ruc tu res on CLay Shales". R. P e t e r s o n and N. P e t e r s , P. F. R.A.

"Prac t i ca l Exper ience with Highly Swell ing Soi l Types". R. M. Hardy, R. M. Hardy & Assocs. , and A. 0. Dyregrov, Underwood, McLel lan & Assocs .

Lunch at Athabaska Hal l

TECHNICAL SESSION # 2

"Physico-Chemical Aspects of So i ls t f G. C. McRost ie, Cha i rman

Cha i rman 's Remarks

"Physico-Chemical Phenomena in Soi l Mater ia ls" S. Pawluk, Universi ty of A Lberta (Soil Science Department) .

"Measurements of Shear Strength, P last ic i ty and Water Retention of Clays Related to In terpar t ic le Fo rces " B. P. Warkent in, Macdonald Col lege, Montreal.

"Shear Strength of a Remoulded, Normal ly Consolidated Homionic Clay" S. Thomson, Universi ty of Alberta.

"Engineering P rope r t i es of I l l i te Related to Fab r i c and P o r e Water Composition" R. M. Quigley, Geocon Ltd.

Bus iness Sess ions:

Soi l Mechanics Subcommittee of Assoc ia te Commit tee on Soi l and Snow Mechanics of the National Resea rch Council.

Geotechnical Division of Commit tee on Technical Operat ions of the Engineering Inst i tute of Canada.

Evening Research Seminar

"Research on the Phys ico-Chemica l Aspects of Soi ls a s Related to their Engineering Proper t ies "

Pro f . D. L. Townsend, Chai rman

Thursday, 13 September 1962 - Combined Soi l Mechanics Conference and Zone "At' Engineering

Inst i tute of Canada

Registrat ion Opening Remarks : Dr . R. M. Hardy , Genera l Chai rman

Mr . F. M. Cazalet , V ice -Pres iden t , EIC P ro f . J. R. Mant le, V ice-Pres ident , EIC Dean G. W. Govier , Univers i ty of A lber ta

TECHNICAL SESSION #3

Pro f . J. Longworth (U. of A. ) Chai rman

"Surf ic ial Deposits in Alberta" C. P . Gravenor and L. A. Bayrock, Resea rch Council of ALberta.

"Engineering Aspects of the Grea t Slave Rai lwayrt J. L. Char les , V. R. Cox anld F. L. Peckover .

"Pre l im inary Soi l Mechanics Aspects of the Red River FLoodway1I J. Mishtak, Soi l Mechanics Water Contro l & Conservat ion Branch, Manitoba Department of Agr icul ture.

Informal Luncheon, Nor thern Alber ta Jubi lee Auditor ium.

TECHNICAL SESSION #4

C. F. Ripley, Chai rman

Chai rman's Remarks "The Columbia River Development - - A P r o g r e s s Repor t r l B r i t i sh Columbia Hydra & Power Authority and Consultants.

(a) The Overa l l P ro jec t (b) The Mica Creek P ro jec t (c ) The Ar row Lakes P ro jec t (d) The Duncan Lakes P ro jec t

"Foundation Trea tment and Construct ion of Sixteen Mi les of Dyke a t Manitoba Hydro 's Grand Rapids P ro jec t r1 A. Koropatnick, W. S. Isom and J. R. Rett ie, Manitoba Hydro.

Stag Dinner Ar ranged by Edmonton Branch, E. I. C. a t Macdonald Hotel Speaker: Dr. K. F. Tupper , P res iden t , Ewbank, Tupper & Assocs . Ltd. and Pas t -P res iden t , E. I. C.

F r i d a y , Sep tember 14

Eng ineer ing Inst i tu te of Canada Zone "A" Techn ica l Meet ing

TECHNICAL SESSION #5

J. C. Da le , Cha i rman

Cha i rman ' s R e m a r k s

"Design of P i p e L ines to Min imize Br i t t l e Fa i lu re " V . P . Mi lo, Shel l Oi l Company.

"The A lbe r ta to Cal i forn ia P i p e L ine System" D. P. Smi th and /o r W. L . Kennedy, Canadian Bechte l Ltd.

"Energy In terchange and a Nat ional Gr id1 ' D. Cas s -Beggs , Saskatchewan Power Corpora t ion

"The A lber ta E lec t r i c P o w e r Situation" G. A. Gaher ty , Mon t rea l Eng ineer ing Co. Ltd. ,

In formal Luncheon Nor the rn A lbe r ta Jub i lee Aud i to r ium Off ic ia l Opening of New Wing of Eng ineer ing Bui lding a t the Univers i ty of A lber ta .

TECHNICAL SESSION #6

Dr. R. W. McManus, Cha i rman

"Oil and Gas R e s e r v e s i n W e s t e r n Canada" J. G. Stabback and R . D. C ra i g , A l be r t a Oi l and Gas Conservat ion Board .

"The Remote Contro l of a Gas Fie ld" J. H. Schwar tz , T imewe l l Con t ro l s Ltd.

T o u r s of Eng ineer ing Labo ra to r i es , Un ivers i ty Campus .

SHEAR STRENGTH O F A REMOULDED NORMALLY CONSOLIDATED HOMIONIC CLAY

by

rOr S. Thomson

SUMMARY

Water in itself and in i t s behaviour i s a complex substance. There a r e Van d e r Waals and Coulombic fo rces operating between the bodies present. Clay part ic le sur faces and edges, f r e e and adsorbed cations and anions a l l possessing charges , presumably a l l interact . Fur ther , charges on the par t ic les a r e not evenly d is t r i - buted but may have points of concentrat ion and the cations dif fer both in s ize and charge. Thermal energy and the infinite var iety of in ter - par tic le relat ionships would appear to compound an a l ready complex system. In most instances a l l that can be measured i s the net effect of these forces.

This paper i s based on the t r iaxia l strength resu l ts obtained by compressing a normally consolidated remoulded chemical ly treated clay soil. It i s concluded that both the adsorbed cation complex and the concentration of sa l ts in the pore water influence the shear strength of a soi l . The main factor considered to account f o r the variat ions in strength a r e the changes in thickness of the adsorbed f i lm that a r e brought about by the adsorbed cation o r sal t concentrat ion in the pore water.

The work that f o r m s the bas is of this paper was car r ied out a s a requirement f o r a Ph . D. degree a t the University of Alberta with financial ass is tance f r o m the Joint Highway Research P r o g r a m of the Prov ince of Alberta. The author expresses his appreciat ion of the help and c r i t i c i sm extended to him by many m e m b e r s of the staff. Of par t icu lar note a r e Dr. R. M. Hardy and P r o f e s s o r S. R. Sinclai r .

* See Appendix "A" for affil iation.

The ro le played by so i l physics and physical chemist ry in explaining the geotechnical behaviour of clay soi ls i s increas ing i n importance and i s contributing to an undertstanding of this behaviour. This paper p resents resu l ts obtained f rom laboratory t r iaxia l tes ts ca r r i ed out on a remoulded, normal ly consolidated clay soi l that was modified by having a high proport ion of the exchange complex occupied by a single cation species. In addition to the natural so i l , the modifi- cat ions studied were those result ing f rom the par t ia l saturat ion of the exchange complex with calc ium, magnesium, potassium and sodium cations.

Sample Preparat ion

The soi l used for this p rogram was obtained f rom a highway cut Located on the southern outskir ts of Edmonton. The cut was opened in the Latter par t of the summer of 1959 and the bulk so i l sample was dug out of the backs lope just above road level in ear ly Apr i l of 1960. Vert ical ly, the sample location was between fifteen and twenty feet below the original ground surface. Five hundred pounds of this so i l was obtained and allowed to a i r d ry in the Laboratory. The ma te r i a l i s a glacial lake sediment c lassi f ied a s a highly plast ic clay. The so i l in i t s natural s ta te contains 45% clay s izes , 53% si l t s i zes , and the remainder sand. After a i r drying and mixing, random port ions were broken down and crushed to pass a No. 40 sieve.

The soi 1 modifications were prepared by washing the soi l with 0 .7 5 normal hydrochloric acid to remove the carbonates and sulphates. It was then washed with one normal acetate solution of the des i red cation and finally centrifuged with ethyl alcohol. After oven

0 drying a t 50 C and crushing, sufficient dist i l led water was added to yield a s lu r r y with a mois ture content slightly in excess of the Liquid l imit. This s lu r r y was consolidated a t a p r e s s u r e of one ki logram per square cent imeter in two-inch inside d iameter lucite tubes four inches long. Tr iax ia l specimens, 35.7 mm. by 80 mm. long were t r immed f r o m the consolidated samples. Each specimen contained 5 internal wool wicks inser ted just before placing in the t r iaxia l cell.

Soi l T e s t s

The specific gravity of the so i l sol ids, C , and the S

grain- s ize distr ibut ion (hydrometer analysis) were determined on each modification in accordance with ASTM-D854- 52 and D422- 54T respectively. The shear strength was determined on a Norwegian Ceonor Tr iax ia l Soil Testing Apparatus e s sentially a s out lined by Andresen et a l (1). The major dif ference was the use of a 2 ki logram pe r square cent imeter backpmssure for this work.

The quantitative determination of the cation exchange capacity and of the exchangeable cations was according to the procedure evolved by the Soil Survey Section of the Alberta Research Council. The cation exchange capacity was based on leaching a smal l soi l sample with ammonium acetate, then doing a kjeldahl nitrogen determination on the ammonia retained by the soil. The exchangeable cations were determined with a Model DU Beckrnan F lame photometer on an ammonium leachate of the soi l sample.

Tes t Resul ts

Analysis of Adsorbed Cations

The exchange capacit ies and the per cent adsorpt ion of the var ious ions a r e l isted in Table I. One batch of soi l provided 3 t r iaxia l specimens. Lack of p rec ise control in leaching and in the f inal alcohol washing gave r i s e to the var iat ions in sal t content and the adsorbed complex. Croup I was the f i r s t group tested and Croup I1 the second. The bas is for grouping i s the dif ference in the sal t contents of the pore water. It i s noted that although homionic conditions were n ~ t achieved, i t was believed that a sufficiently high proport ion of a single cation species was adsorbed so that i t s behaviour would not be affected. Although not fully achieved, the homionic condition was attempted in order to enhance single cation effects and to reduce o r el iminate the influence of one cation type on another.

Specific Gravity of Soil Solids

Table 2 presents the resu l ts of specif ic gravity tes ts a s determined by the standard pycnometer procedure. The var iat ion in resu l ts i s significant part icular ly when one cons iders that the natural soi l has calcium and magnesium occupying 98% of the exchange positions. The two readi ly apparent fac to rs influencing these values

a r e the adsorbed cation complex and the presence of sal ts in the pore water.

Where soluble sa l ts a r e present in the pore water , the dry weight of the soi l i s increaeed by the weight of sal ts. Fo r smal l amounts of soluble sa l ts there is practical ly no weight loss when they a r e dissolved in water. If the formula fo r calculating the specific gravity of the soi l solide i s considered, the ext ra weight of sa l ts appears in the numerator but not in the denominator. It i s apparent, therefore, that the presence of soluble sa l ts in the pore water increases the observed value of the specific gravity of the soi l solids. If the sa l ts a r e insoluble, they wil l ac t like another soi l grain and the observed specific gravity will be an average value, either lower o r higher depending on whether the salt i s l ighter or heavier than the so i l part ic les. Fo r most soi ls this effect will likely be smal l .

The amount of adsorbed water in the case of sodium soi l in the a i r d ry state wil l be greater than that f o r calcium in the air dry state because of the greater surface a r e a of the sodium modifi- cation. This a lso leads to an observed specific gravity that i s higher in the case of sodium soi ls than calcium soi ls.

The influence of the adsorbed cation and the presence of sal ts in the pore water can not be separated. There i s an interplay of these two factors, for example, the presence of sal ts depress the thickness of the water hull. Since the variat ions of specific gravity depend to some extent on the surface a r e a and activity of the soi l part ic les larger discrepancies wil l be found with montmori l lonites than with kaolinites.

Hydrometer Analysis

A soi l part ic le in suspension may be considered to consist of a soi l nucleus surrounded by a water f i lm. Manipulations of the formulae used in the hydrometer analysis with var ious assumptions concerning part ic le s ize and thickness of adsorbed water f i lm indicate that the influence of the adsorbed cation complex on the water hull of a part ic le does not have a very significant influence on the reeulting grain s ize curve. The resul ts of teste shown in Fig. 1 reveal , however, a considerable difference of grain distribution part icular ly fo r the sodium

modification. Gr im (2) suggests that the reason fo r the inc rease in the per cent clay s izes i s the greater tendency f o r par t ic les to break down along cleavage planes during d isper sion when sodium occupies a high per cent of the exchange positions. The type of clay m ine ra l would ref lect to some extent in the grain- s ize distr ibut ion, part icular ly the montmori l lonites.

Tr iax ia l Consolidation

During t r iaxia l consolidation a plot of buret te reading ve rsus the logari thm of t ime was kept for each sample. Table 3 l i s ts the t imes of theoret ical lOO'j'o consolidation obtained f r o m these plots. Typical plots a r e i l lustrated on Fig. 2.

The resu l ts in Table 3 show that there i s a cation effect on the t ime ra te of consolidation. The mechanism appears to be a physical clogging of the pore space by the adsorbed water f i lms a s i s evidenced by the fact that the sodium cation, which i s assoc ia ted with a thick water hull around the par t ic le , yields the modification requir ing the longest t ime. There would appear to be two effects, one decreas ing the pore diameter and the other decreas ing the number of channels by seal ing off those of sma l l d iameter . In addition, the breakdown of clay par t ic les when sodium i s adsorbed leads to a f iner grained soi l m a s s which in turn resu l ts in a longer t ime for consolidation to cccur.

Table 3 a lso shows that there i s a noticeable influence exerted on the t ime ra te of consolidation by the p resence of sa l ts in the pore water. With the exception of the potassium so i l , the higher concentration of sa l ts in the pore water i s associated with a decrease in the t ime required fo r consolidation to occur. The reason postulated f o r this i s that the sa l ts present in the pore water have the effect of decreas ing the thickness of the adsorbed water f i lms on the clay par t ic les and a lso tend to flocculate the part ic les. This was substantiated by a single test ca r r i ed out with sodium modified specimen having a high sal t content in the pore water (118 m . e. per 100 gm. a i r dr ied soil). The t ime to theoret ical 1000/o collsolidation fo r this sample was 350 minutes, less than 170 of the t ime required fo r the specimen with no sa l ts in the pore water.

Consolidated - Undrained Strength

The data observed for each test consisted of the deviator s t r e s s and the pore p r e s s u r e in the water phase. F r o m this data the ma jor and minor pr incipal and their ra t io were calculated. Typical plots of deviator s t r e s s e s and pore p r e s s u r e ve rsus s t ra in a r e shown on Figs. 3 and 4 respectively. F r o m a study of these plates i t appears necessary to offer a tentative explanation fo r the low deviator s t r e s s e s and pore p r e s s u r e s measured in the sodium modified samples.

The start ing point fo r this tentative explanation i s the fact that thick water hulls adsorbed on clay par t ic les a r e associated with the sodium cation ( 3 ) . These water hul ls must be in contact o r somewhat intergrown a s i s suggested by the t ime ra te of consolidation data. Since the oriented water layers a r e relat ively f a r f r om the clay par t ic le sur face, the degree of orientat ion a t the f r inges i s probably not very strong. However, there i s some s t ruc tu re in the adsorbed water and in the overlapping port ions of adjacent water hulls. The thickness of the water hulls leads to higher void ra t ios hence higher mo is tu re contents. The water hul l thickness a l so inc reases in terpar t ic le spacing therefore reducing in terpar tic le at t ract ions and repulsions. The monovalent sodium ion i s not capable of tying adjacent soi l par t ic les together.

The sum of these concepts leads to the conclusion that the shear strength of the sodium modified soi ls must be low. These effects a r e a lmost reversed fo r the divalent magnesium and calcium cations. A thin water hull around the clay part ic le i s associated with these cations which allows higher in terpar t ic le at t ract ions and repuls ions and possibly a tying of par t ic les together due to the divalent nature of the cations.

In the consolidated-quick test per formed fo r this repor t , i t was consistently observed that there was a smal le r proport ion of the applied deviator s t r e s s t rans fe r red to the water phase of the sodium modifj.ed samples than with the other modifications. The suggested explanation fo r the lower pore p r e s s u r e s developed in the sodium modified so i ls i s developed by the following t ra in of thought, P r e s s u r e in the pore water of a soi l sample a r i s e s because there i s a t ransfer of a n applied s t r e s s to the water phase f r o m the soi l skeleton.

In this context the soi l skeleton i s meant to include the adsorbed water hull. The t rans fe r of s t r e s s to the water phase impl ies a s m a l l dec rease in volume of the so i l skeleton. F r o m th is , i t fol lows that re lat ively r ig id so i l s t ruc tu re wi l l resu l t in low pore p r e s s u r e s whereas a soi l s t ruc tu re capable of decreas ing in volume wil l resu l t in high pore p r e s s u r e s . It i s suggested that the or iented water molecu les within the overlapping water hul ls impa r t sufficient r igidi ty to the soi l s t r uc tu re to c a r r y the init ial ly imposed deviator s t r e s s . Th is mechanism a l so al lows f o r the low deviator s t r e s s e s observed fo r the sodium so i ls s ince the applied s t r e s s e s need only d isrupt the or iented water net.

The thin and wel l defined water hulls around clay par t ic les assoc ia ted with the divalent calc ium and magnes ium cat ions do not over lap between soi l par t ic les . There fo re , when s t r e s s i s appl ied the soi l par t ic les can shift o r s l ide over one another sufficiently to br ing about a sl ight volume dec rease and to generate the higher pore p r e s s u r e s observed.

The mechanism postulated may a l so be used to account f o r the fact that the sodium samples fa i l at a much lower s t ra in than do the other modif icat ions. Once the ini t ial s t r a i n has d isrupted the or iented and overlapping water net of the sodium soi l , the s t rength dec reases due to the water being in a f r e e s ta te . Pa r t i c l es with large water hul ls wi l l s l ide past one another with re la t ive e a s e thus in terna l f r ic t ion wi l l be at a min imum. On the other hand fo r the divalent cat ion modi f icat ions, in terpar t ic le a t t rac t ions and repuls ions have to be overcome and because the thin water hul ls do not smooth out par t ic le i r r egu la r i t i es , in terna l f r ic t ion can continue to build up to much higher s t ra i ns ,

Mohr P lo ts

The Mohr P lo ts of ef fect ive s t r e s s e s s e r i e s of tes ts a r e shown on Fig. 5 and summar ized in Table 4. Each envelope i s defined by a t least three tes t resu l t s except that f o r the sodium sample with a high sa l t content in the pore water which i s a single test resu l t .

The Mohr plots revea l two dist inct f ac t s . One, that the adsorbed cat ion complex does affect the angle of in terna l f r ic t ion and, secondly, that the sa l t content of the pore o r f r e e water has a pronounced effect on the s t rength of a given modif icat ion. At this t ime

these resu l ts must be considered m o r e a s qualitative than quantitative due to the uncontrolled sal t contents. The genera l conclusions, however, a r e st i l l considered to be valid.

The postulates previously presented appear to account for the dif ferences in the angles of internal fr ict ion. The potassium and magnesium have relat ively thin water hulls which resu l t in lower void ra t ios and m o r e in terpar t ic le in ter ference. The effect i s to inc rease the angle of internal fr ict ion. The Mohr envelope for the calcium and sodium modifications offer supporting evidence fo r the ro le played by the thickness of the adsorbed water f i lm on the par t ic les. Sodium clay, having the thickest water hull, has the lowest angle of internal fr ict ion. The effect of sa l ts in the pore water i s a l so exemplif ied by the sodium and calcium soi ls. An inc rease in sal t content resu l ts in significant strength increase. The presence of sa l ts has the effect of decreas ing the adsorbed water f i lm thickness on the soi l par t ic le enhancing in ter - par t ic le friction. Sodium soi ls with high sal t contents have strengths comparable to the other modifications.

In summary , the var iat ions i n strength a r e attr ibuted to changes in thickness of the adsorbed water f i lms on the clay part ic les. The thick water f i lms associated with the adsorbed sodium cation tend to overlap between par t ic les which p resents a sufficiently r igid soi l s t ructure to ini t ial imposed s t resses . Due to this s t ruc tu re , a la rger proport ion of the applied s t r e s s i s car r ied by the soi l skeleton which i s manifested i n lower pore -8ater p ressu res . A smal l amount ol s t ra in d isrupts the water nets and accounts for the sodium fail ing a t low s t ra in values. The thick water hul ls a lso smooth out the par t ic les and reduce interpart ic le fr ict ion result ing in low strengths.

Fur ther Considerat ions of this Work

It has general ly been accepted that a plot of the mo is tu re content ve rsus the logari thm of the compress ive strength resu l ts in a stra ight line f o r saturated cohesive soi ls. The resul ts of these tests have been plotted on Fig. 6. The data strongly suggests that the l inear variat ion only holds when the adsorbed cation complex o r the Level of sa l ts in the pore water does not change. There i s some indication f r o m Fig. 6 that an inc rease in the sal t content f lattens the slope of the curve; that i s , i t tends to impar t to the soi l those charac te r is t i cs associated with

a so i l of low cohesion. Th i s d e c r e a s e of cohes ion a s the sa l t content i n c r e a s e s s e e m s to a g r e e with the behaviour of a clay so i l when a non-polar f luid takes the p lace of wa te r . T h e s e r e s u l t s a l s o appea r to

ind ica te that the th ickness of the adsorbed wa te r f i l m a round a c lay pa r t i c le m u s t be taken in to account when studying the phenomena of cohesion.

Tay lo r (4) and o t h e r s d i s c u s s the concept that a plot of the m o i s t u r e content v e r s u s the logar i thm of the compress i ve s t reng th and the v i rg in compress ion b ranch of the p ressu re - vo i d r a t i o cu r ve fo r sa tu ra ted cohesive so i l s should resu l t i n two pa ra l l e l l ines. The data f r o m th is tes t s e r i e s and the consol idat ion data f r o m the work of Hami l ton (5) a r e plotted on Fig. 7 . In s e v e r a l i ns tances t he re i s a m a r k e d deviat ion f r o m pa ra l l e l i sm of the cu r ves desp i te the paucity of the data . The m a j o r d i f fe rences between samp les i s the amount of sa l t s i n the p o r e wa te r and i t a p p e a r s that pa ra l l e l i sm wi l l occu r only when the so i l samp les a r e ident ica l including the sa l t content of the po re wa te r . At th is t ime t he re i s insuff ic ient da ta on which to b a s e f u r t he r conclus ions.

The swel l ing p r e s s u r e exer ted by s o m e so i l s has p resen ted in te res t ing p rob lems i n recen t y e a r s . In a t tempt ing to expla in th is phenomenon i t is suggested that swel l ing p r e s s u r e s a r e Largely due to i n c r e a s e s i n th ickness of the adsorbed wa te r f i lm. Assuming that reor ien ta t ion of wa te r mo lecu les i n the f o r ce f ie ld of a c lay pa r t i c le i s a c rys ta l l i za t ion p r o c e s s , then i t would appea r logical to postu la te that th is reor ien ta t ion r esu l t s i n swel l ing p r e s s u r e s . If one cons ide r s a so i l m a s s in a re lat ive ly dense s ta te with a high Level of sa l t s i n the po re wa te r and reasonab ly pu re wa te r becomes ava i lab le to the m a s s , i t i s suggested that the fol lowing wi l l take p lace. F i r s t l y , osmot ic p r e s s u r e wi l l develop due to the di lut ion of the p o r e f lu id and , secondly, th is di lut ion wi l l a l low the adsorbed wa te r f i lms to expand. Both of these mechan i sms wi l l give r i s e to swel l ing p r e s s u r e s and wi l l continue to do s o , ~ n t i l a n equ i l ib r ium is estab l ished. If the wa te r ava i lab le to the so i l m a s s conta ins s a l t s , both the m e c h a n i s m s wi l l be reduced i n magni tude.

Consider ing f ie ld p rob lems , two ma jo r points appea r to be the sa l t level of the groundwater and the composi t ion of wa te r moving through a so i l m a s s . It i s poss ib le to d e c r e a s e the overa l l sa l t content of the po re wa te r leading to s o m e s t reng th reduct ion o r i t i s

possible to affect a cation exchange which m a y a l so Lead to s t rength reduction. This la t ter dec rease mus t be the resu l t of f i r s t a n exchange of cat ions, for example, sodium replacing ca lc ium, followed by a reduction of the sa l t level in the so i l m a s s . In consider ing the genera l feasibi l i ty of such occur rences in the f ie ld , there a r e two points that mus t be kept i n mind. In many of the so i ls of A lber ta f r e e gypsum crys ta ls a r e often found. These a r e suff ic ient ly soluble to maintain a reasonable sal t level in the pore water . If the soi l i e Leached with a solution containing divalent and monovalent cat ions, there i s a preferent ia l adsorpt ion of the divalent ion (6). Both these factors mit igate against a strength loss due to cation exchange o r salt level decrease .

REFERENCES

1. A. Andresen, L. Bje r rum, E. DiBaggio and B. K jaerns l i - Tr iax ia l Equipment Developed a t the Norwegian Ceotechnical Institute; NCI Publ icat ion No. 21, Oslo , 1957.

2. R. E . Gr im - Applied Clay Mineralogy; McCraw-Hil l , 1962.

3. Organizat ion of Water on Clay Minera l Sur faces and I ts Implicat ions f o r the P rope r t i es of Clay-Water Systems; Research Board, Special Report No. 40, 1958.

4. D. W . Taylor - Fundamentals of Soi l Mechanics; Wiley, 1949.

5. A. B. Hamilton - A Fu r the r Study of Cation Effecte on the Phys ica l P rope r t i es of CLays; M. Sc. Thes is , University of A lber ta , 1961.

6. W. P. Kelley - Cation Exchange in Soi ls; Reinhold, New York, 1948.

Soil Modification

Natura l

Po tass ium

Calc ium

Sodium

Magnesium

TABLE I -

FLAME PHOTOMETER RESULTS

Exchange .,, P e r c e n t Adsorbed of Sa l t s i n * Capacity Group Calc ium Sodium Po tass i um Magne siurn P o r e Wate r

Notes:

1. *- -Group I cons is ts of f i s t 3 samp les only f o r each ~ ~ o d i f i c a t i o n (consol idated Z a t 1. 5, 2 . 7 5 and 4 k g / c m ). Al l subsequent samp les compr i se Group 11.

2. Sa l t s in po re water calculated a s d i f ference between exchange capaci ty by d is t i l la t ion and tota l of f lame photometer r esu l t s .

3. Exchange capacity and sa l t s in po re water given a s mi l l iequivalents p e r 100 gm a i r d r i ed soi l .

TABLE 2 -

SPECIFIC GRAVITY O F SOIL SOLIDS

Sa l ts i n P o r e Water Average Specif ic m . e. 1100 gm. air

Modification Gravi ty d r y so i l

Natura l 2.78 7 4

Calcium 2.73 10

Magnesium 2. 68 16. 5

Sodium 2.79 0

Po tass ium 2.71 32

TABLE 3

TIME IN MINUTES FOR 10070 THEORETICAL CONSOLIDATION IN TRIAXIAL C E L L

MODIFICATION

Ce 11 * P r e s s u r e K S. C. Ca SC Mg SC Na SC

1. 5 9,700 31.8 500 21.8

2 .75 14,000 31.8 160 21.8

4. 00 13,000 31.8 170 21.8

5. 25 3,900 5. 1 140 9 .8

6. 5 3,900 5. 1 87 0 9. 8

7 . 5 4,500 5. 1 17 5 9.8

*SC = Salt content in the pore wa te r , m. e

390 1 .8 39,000 0

300 1.8 30,000 0

170 1 .8 46,000 0

150 16.5 39,000 3.8

170 16.5 40,000 3 .8

150 16.5 22,000 3.8

p e r 100 gm. of air dr ied soi l

T A B L E 4

SUMMARY O F STRENGTH PARAMETERS -

Sal t Content of P o r e Wate r To ta l S t r e s s Ef fect ive S t r e s s m. e. / l o 0 gm.

2 Q,

2 Q, Modif icat ion air d r i e d so i l K g / c m d e g r e e s Kg/ c m d e g r e e s

Ca lc ium

Sodium

Magnes ium

Natu ra l 74

0

P o t a s s i u m 3 2

5

22

10

0

4

118

2

16

* Single t es t r e s u l t , cohes ion a s s u m e d equa l t o z e r o

FIGURE I

PARTICLE SIZE DISTRIBUTION

OF THE CLAY MODIFICATIONS

by hydrometer analysis

FIGURE 3 STRESS - STRAIN RELATIONSHIPS FOR T H E CLAY MODIFICATIONS

3

N E

I I I I 1 I I 1 I I I

- -

Natural Clay<

0 \ __-__ _ _ _ _ Magnesium . . --- C l a H - - _ - - - - 0 -- -- z --- - - /- Calcium Cloy

Potassium Cloy -

Tr iax ia l Cel l P ressu re = 4 kg/cm2

0 I I 1 I I I I I I I

0 I 2 3 4 5 6 7 8 9 10 I l 12 AXIAL COMPRESSIVE STRAIN, %

2 - 2 - Natural Clay Calcium Clay

1 0 I I I 0 I 2 3 0 I 2 3

EFFECTIVE NORMAL STRESS , kg / cm2

2

I

2t Magnesium Clay

- 2 - Sodium Clay Potassium Cloy

/ / - (118)/

Note: pore water salt content noted on each curve (milliequivalents per 100 grams of air dried soil)

Dashed envelope for sodium clay is drawn from a single test result

0 I 0 I 2 3 0 I 2 3

FIGURE 5 MOHR ENVELOPES FOR THE CLAY MODIFICATIONS

$ Potassium Clay

i 50 Z W I- o z o 40 I\\ ( 0 )

W

DEVIATOR STRESS AND CONSOLIDATION PRESSURE, kq /cm2

Magnesium Clay

Note: Pore water salt content noted on each curve (milliequivalents per 100 grams of air dried soil )

3 4 5 6 7 8 10

FIGURE 7 RELATIONSHIP BETWEEN MOISTURE CONTENT, VIRGIN COMPRESSION BRANCH AND DEVIATOR STRESS FOR THE CLAY MODIFICATIONS

THE ENGINEERING PROPERTIES O F ILLITE RELATED TO FABRIC AND PORE WATER COMPOSITION

R. M. Quigley

SUMMARY

Engineer ing t es t s have been per fo rmed on a n i l l i te lay containing about 30 pe r cent of vermicu l i te and chlor i t ized ermicu l i te . The tes ts we re per fo rmed in control led sa l t environments

consist ing of NaCl and KCL. The c lays w e r e sodium saturated, deposited in 0 . 154 Normal NaCl and then leached with 0. 154 Normal solut ions of e i ther Nacl o r KCl. Different consolidation and s t rength p roper t ies we re observed on the clay depending on whether i t was leached with NaCl o r KCl. A fabr ic study, per fo rmed using x - ray di f f ract ion techniques, showed that the Na and K c lays had di f ferent average par t ic le a r rangements . Most of the d i f ferences in so i l fab r i c and engineering p roper t ies of the Na and K c lays can be at t r ibuted to the di f ferent adsorbed cat ions p resen t . Although a l imited amount of potass ium fixation and layer Lattice col lapse did occur in the so i l vermicu l i te when Leached with KCl, the ef fects of the resu l t ing expulsion of in ter layer water we re general ly swamped by the effects of ord inary cat ion exchange.

During ac id weather ing, considerable i n te r layer potass ium m a y be removed f r o m so i l i l l i tes o r m i c a s producing "degraded" i l l i tes o r ve rmicu l i tes which can expand apprec iab ly and m a y behave somewhat like montmor i l loni te. Upon t reatment with KC1 solut ions they col lapse back to a non-expanding mica . Th is col lapse occurs in nature when degraded i l l i tes f ix potass ium upon enter ing a m a r i n e environment. The react ion has been cal led c lay m i n e r a l "diagenesis" (change in minera logy a f ter deposit ion) by some w r i t e r s and cat ion exchange with f ixat ion by o thers . (eg. Weaver , 1958a and 1958b; Powers , 1957).

The purpose of the r e s e a r c h descr ibed h e r e was to determine the re la t ive effects of potass ium f ixat ion and ord inary cat ion exchange on the engineer ing p roper t ies of a potass ium deficient i l l i te in control led solut ions of NaCl and KCL. The degraded so i l i l l i te used i n m o s t of the exper iments was obtained f r o m a Podzol ic so i l prof i le in which acid weather ing had reduced the potass ium content to a fa i r l y low level. Although a m ino r amount of col lapse did occur a s a resu l t of KC1 leaching, the so i l behaved essent ia l ly l ike an i l l i te and the changes in p roper t ies w e r e due p r imar i l y to o rd inary cat ion exchange. The col lapse of the c lay was prevented by adsorbed aluminum and i r o n hydroxide complexes which had rep laced the potass ium resu l t ing i n par t ia l chlor i t izat ion of the degraded i l l i te or ve rmicu l i te in the so i l prof i le. Different consolidation and s t rength cha rac te r i s t i c s which we re measu red on the Na and K c lays , a r e the subject of this paper .

Soi l fab r i c studies per fo rmed on consol idated speci- m e n s showed that the Na and K c lays had dif ferent par t i c le a r rangemen ts which could be measu red semi-quant i tat ively by x - ray methods. Additional studies on sheared i l l i te and kaol ini te spec imens showed that shear ing produces marked par t i c le or ientat ion. The di f ferences i n so i l fab r i c and engineering p roper t ies of the i l l i te can be explained i n t e r m s of Rosenqv is t 's concepts of cat ion polar izabi l i ty o r re la ted to the s i ze of the hydrated cat ions adsorbed on the clay.

MATERIALS AND METHODS

Clay Mineralogy

The clay so i l used for test ing was obtained f r om a

Podzol ic so i l prof i le located near the c r e s t of a druml in in Eas t Boston, Massachuset ts . The clay was separated f r o m the t i l l by high speed centr i fugation. The so i l came f r o m the upper 1. 5 feet of the prof i le where the measu red pH of the soi l water was 4 to 4. 5 . The K 0 content of the clay was 3 to 4 pe r cent o r about half that of

? norma i l l i tes .

The so i l mineralogy was studied in detai l using a var ie ty of methods including x - ray dif fract ion, d i f ferent ia l t he rma l ana lys is and glycol retent ion. X- ray spectographic p rocedures w e r e used to determine the cat ion exchange capaci ty, total potass ium, and extractable a luminum and i ron. Detai ls of the clay minera logy and the minera log ica l tes t p rocedures have been published e lsewhere (Quigley and Mar t in , 1961) and wi l l not be repeated he re . Although seve ra l batches of clay were tes ted, a l l showed essent ia l ly the same proper t ies despi te Large di f ferences in gra in s ize. Batches 2 and 3 mentioned h e r e , consisted of s i zes sma l l e r than 2 mic rons and 0 . 4 m i c r o n s , respect ively. A brief descr ipt ion of the composit ion of the clay used for engineering test ing follows.

The clay was composed chiefly of i l l i te with up to 30 per cent of ch lor i te and so i l vermicu l i te . A typical x - ray dif fract ion t r ace of a n or iented spec imen hornionic in Na i s shown on Fig. 1. The strong 10. 1 angs t rom peak a t the left s ide of Fig. 1 is charac te r i s t i c of i l l i te . The 14 .3 and 7 . 4 angs t rom peaks indicate the p resence of chlor i te and vermicu l i te . Heat t reatment and sodium c i t ra te extract ion studies indicated that i r on and aluminum ch lor i tes w e r e both present . Although pgtassium saturat ion caused the vermicu l i t i c phase to col lapse back to 10 A i l l i te , the change was not permanent and the potassium could general ly be easi ly exchanged by sodium. The cat ion exchange capacity of the clay var ied f r o m 20 to 35 mil l i -equivalents pe r 100 g r a m s of c lay, depending on the s i ze of the clay f rac t ion and i t s Location i n the soi l prof i le. Aluminum and i r on hydroxide complexes w e r e found to have chlor i t ized much of the so i l vermicu l i te thus preventing col lapse of the s t ruc tu re (Quigley and Mar t in , 1961). Of par t icu lar p rac t i ca l i n te res t was the fac t that extensive leaching with solut ions of NaCl, and KCL i n par t i cu la r , resu l ted in the remova l of some of the adsorbed AL and F e hydroxide complexes and an i nc rease i n cat ion exchange capacity. Any long-term i nc rease in exchange capacity would probably have affected the engineering tes t r esu l t s , s o a l l t es t s , with the exception of consoli-

dation 34 w e r e c a r r i e d out G - ~ e r the s a m e per iod of t ime.

Methods of Eng ineer ing Tes t ing

T h e c lay s a m p l e s w e r e sod ium sa tu ra ted by washing them s e v e r a l t imes in 1 N o r r n ~ l NaCL so lu t ions . They w e r e then brought i n t ~ equ i l ib r ium with 0. 154N NaCl and deposi ted in 0. 154N NaC! solut ions. One p a r t p e r mi l l ion m e r c u r i c ch lor ide was used to p reven t any b io logical act iv i ty f r o m developing i n the c lay sed iment . The s a m p l e s w e r e al lowed to conso l ida te in the consol idat ion chambe r under the i r own weight and then under the weight of a l ight po rous s tone, Al l samp les w e r e then Leached under the s a m e head with 0 . 154N solut ions of e i ther NaCl o r KCl. Dur ing the 8 o r 9 day leaching pe r i od , 2 to 3 so i l vo lumes of leachate passed through the sed imented samp les . The leached c lays w e r e subsequent ly consol idated to p r e s s u r e s of up to 8 tons p e r squa re foot. Pe rmeab i l i t y va lues w e r e de te rm ined f r o m both the consol idat ion t es t r e s u l t s and f r o m fa l l ing head t es t s r un on the c lay a t the end of the load i nc remen ts . T e m p e r a t u r e e f fec ts w e r e e l iminated by runn ing the consol idat ion t es t s in a constant t empe ra tu re room.

The consol idated c lay s a m p l e s w e r e tes ted in undrained s h e a r using a spec ia l ly bui l t m in i a t u re vane turned wi th the a id of a sens i t i ve Wa te r s to rque g l ass . S t r a i n w a s not m e a s u r a b l e with the appara tus employed and fa i l u re w a s reached i n about one minute .

The p o r e f luid i n the consol idated c lay samp les was analyzed for sodium and po tass ium using a f l a m e photometer .

T h e clay rema in ing a f t e r the vane tes t ing was comple ted, was remoulded and tes ted in dra ined s h e a r us ing a d i r ec t s h e a r mach ine .

The K: Na r a t i o was found to have such a n impor tan t effect on the d ra ined s t reng th that s e v e r a l s a m p l e s w e r e washed i n KC1 to r emove a l l of the adsorbed sodium p r i o r to test ing.

F a b r i c s tud ies w e r e r u n on care fu l ly p r e p a r e d a i r d r i ed c lay spec imens using x - r a y d i f f ract ion techniques desc r ibed prev ious ly (Quigley 1961). B r ie f l y , the method cons is ted of care fu l ly gr inding a f lat su r f ace on a block of a i r d r y clay cut f r o m a n eng ineer ing tes t spec imen. The block w a s then mounted i n the d i f f rac t ion mach ine and the p r e p a r e d su r f ace was x - rayed . Success ive l aye r s could be

ground off the spec imen s o that a s e r i e s of su r faces pass ing through a shear fa i lu re zone could be x- rayed. The degree of or ientat ion

of the clay plate lets could be semi-quanti tat ively determined by compar ing the height of the ( 0 0 f ) and (hk2) x - ray peaks obtained on sur faces of equal a r e a .

TEST RESULTS

The resu l t s of the engineer ing tes ts and the fabr ic study a r e presented under sepa ra te headings below. The chemica l data requ i red for contro l a r e presented with the engineer ing resu l t s .

ENGINEERING STUDY

Index Tes ts

A t te rberg l imi ts run on the clay showed that KCL leaching caused both the liquid and plast ic Limits to i nc rease . Typical r esu l t s we re obtained f r o m Eatch 3 on which liquid l imi ts of 99 and 120 w e r e obtained for the Na and K c lays , respect ively. The corresponding plast ic Limits were 40 and 47, respect ively.

Consolidation T e s t s

Typical consolidation curves a r e shown on F igs. 2 and 3 fo r the Eatch 2 and Batch 3 c lays , respect ively. It i s obvious that the KCL leached c lays exist a t a higher void ra t io than the Na c lays a t any consolidation p r e s s u r e within the range studied. The g rea tes t sp read in the curves occu rs for those c lays which w e r e mos t highly .

leached and hence had the highest K: Na ra t ios . The K:Na ra t ios we re determined a f t e r the consolidation tes ts we re completed by measu r i ng the K and Na p resen t in the pore f lu id of samples cut f r o m the tes t spec imens. The ra t ios a r e recorded on the f igures.

Strength Tes ts

Undrained and dra ined shear s t rength envelopes for the clay f r om Batch 3 a r e shown on Fig. 4. Any d i f ferences in the undrained vane s t rengths of the Na and K c lays, if p resen t , a r e too sma l l to be of signif icance. The dra ined tes t s , on the other hand,

showed pronounced changes depending on the K:Na rat io. A drained f r ic t ion angle of 16 degrees was measu red on the Na clay. Th is angle inc reased to 20 deg rees fo r a par t ia l ly leached c lay having a K:Na ra t io of 1. 5 : l . When the c lay was washed with KC1 unti l a l l of the Na had been removed, the f r ic t ion angle inc reased to 23 degrees . The co r rec ted posit ion of the middle point on this s teeper envelope conforms with seve ra l other envelopes and semi- log plots of the data. A s im i la r i nc rease in dra ined f r ic t ion angle was observed f o r the c o a r s e r clay f r o m Batch 2. In this case , ad i nc reased f r o m 20 deg rees f o r Na clay to 26 degrees f o r the s a m e clay with a K:Na ra t io of 2. 9: l . In Fig. 5 , the drained shea r s t rengths a r e plotted against wa te r content. Th is plot shows even m o r e str ik ingly the magnitude of the changes and the signif icance of the K:Na rat io. The K c lays a r e considerably s t ronger than the Na c lays, the s t rength increas ing a s the K:Na ra t io i nc reases . It should a l s o be mentioned h e r e that the undrained vane s t rengths of the K c lays we re g rea te r than the Na c lays a t a l l water contents within the range studied. The undrained s t rength di f ferences we re not near ly a s pronounced o r consistent as those of the drained tes ts and a r e bel ieved to have been affected by clay par t i c le or ientat ion i n the consol idated spec imens tested ( s e e Fab r i c Study).

FABRIC STUDY

Maximum and Minimum Para l l e l i sm

Maximum para l le l i sm of the c lay plate lets was obtained by high speed centr i fugation of a d ispersed c lay suspension onto a porous ce ram ic plate. An x - ray dif fract ion t r ace of a highly or iented, g lossy layer of kaol ini te is shown by curve (a) on Fig. 6. Minimum para l le l i sm o r a net randomness was obtained by x- ray ing a level sur face of clay powder. A typical di f fract ion t r a c e i s shown by curve (d) of Fig. 6. The (001 ) and (hkg ) peaks shown on curve (d) a r e qui te sma l l and about the s a m e s ize. Pa r t i c l e para l le l i sm great ly enhances the s i ze of the (00 (2 ) peaks as shown by curve (a). Simi la r cu rves were obtained fo r the i l l i tes tested.

Anisotropical ly Consolidated I l l i te

Smal l rec tangular b locks, a l l but consolidation 31 having top and s ide a r e a s within 3 per cent of each o ther , w e r e cut

f r o m the consolidated samples of consol idat ion tes ts 31 through 35 shown on Fig. 3. One top and side sur face of each block was ground f lat and x- rayed. An approximate a r i thmet ica l co r rec t ion for the sma l l e r a r e a was applied to test 31. In Fig. 7 the height of the (003) basa l peaks f r o m the top su r faces and the height of the 4 .48 i ( h k 0 ) peaks f r om the s ide sur faces a r e plotted against the max imum p r e s s u r e to which the samples we re consol idated. Although the data i s ra ther meagre , i t does appear as though the Na c lays have the l a rge r x - ray peaks a t a given p ressu re . Th is indicates that they have been m o r e highly or iented perpend ic~ i la r to the di rect ion of the consolidation p r e s s u r e than the K clays. In other wo rds , the K c lays have a m o r e Dpen s t ruc tu re hence their higher void ra t io a t a given p ressu re . The anomalous posit ion of consol idat ion 34 i s probably re la ted to the fact that i t was the only specimen recycled and subjected to two in terva ls of leaching. A s mentioned previously, extended leaching per iods caused the cation exchange capacity to i nc rease a s strongly adsorbed A1 and F e hydroxide cat ions we re slow Ly removed.

F ig . 8 i l l us t ra tes the par t i c le or ientat ion within a sheared dra ined d i rec t shea r sample which was a i r dr ied sa~bsequent to test ing. The test conditions a r e s h o ~ n on the F igure . It can be seen that a marked para l le l i sm h a s developed due to shea r near the bottom of the sample. The .:orresponding water content in this zone of shear was 65.7 per cent compared to 66.8 per cent near the top. Visual examination of the dr ied d i rec t shear spec imens indicated that the fa i lu re plane was al.ways a rcua te in shape, curving e i ther towards th? top o r the bottom in o rder to conform with the di rect ion of th? pr incip le s t r e s s e s a t the edges of the shea r box. On the bas is of the x - r a y resu l t s the plots O F water content v e r s u s dra ined s t rength w e r e p repared using the lowest of the th ree mo is tu re contents measu red ra the r than a n average f o r the whole sample. The selected values produced much smoothzr cu rves than dld the average water contents.

Although not re la ted to the i l l i te study, a n analys is of the fabr ic in the fa i lu re zone of a t r iax ia l sample of kaol ini te was of considerable signif icance and is worth descr ib ing here . An a i r d r ied t r iax ia l sample of highly f locculated kaolinite ( s m a l l e r than 2 mic rons ) was ,~b ta ined f r o m A. Wissa (1961). The spec imen had been fa i led in undrained shea r over a per iod of 50 hours . The shea r d isplacement

was of the order of 2 mi l l imeters and occurred in a shear zone about 2 mi l l imeters wide. Sharply defined s l ip sur faces were c lear ly visible.

According to Wissa, (personal communication) about 80 per cent of the excess pore p r e s s u r e built up during shear was retained in the sample a f te r the deviator s t r e s s was completely removed. This can be explained by hypothesizing par t ic le reor ientat ion inside the fa i lure zone of the flocculated sample. B je r rum, 1961, descr ibed a se r i es of tes ts on extremely sensit ive Norwegian quick clays which showed s imi lar resu l ts . He hypothesized par t ic le reorientat ion in the fa i lure zone to explain his high! "A" fac to rs and his high residual pore p ressu res af ter removal of the deviator s t r e s s .

The resu l ts of x- ray diffraction tes ts on Wissa 's sample a r e plotted in Fig. 9. The very pronounced inc rease in height

0 oi the 7A (001) kaolinite peak indicates marked par t ic le orientat ion within the shear zone. The plot of the 4. 35A (hkO) peak a l so shows a slight inc rease in height. This may be due to an inc rease in density of the kaolinite within the shear zone af ter a i r drying. The grea ter para l le l ism permi ts greater shrinkage and hence a greater d ry density.

In Fig. 6 , four dif fract ion t races of the same Georgia kaolin a r e i l lustrated. Curve (a) represents maximum para l le l ism produced by centrifugation a s descr ibed previously. Curve (d) i s a powder pat tern represent ing complete randomness. Curves (b) and (c) we re obtained inside and outside of the shear zone, respectively. In a l l cases , the a r e a of sample exposed to x - rays was the same. It i s obvious that although considerable par t ic le orientat ion has been produced by the shear ing, i t i s not great when compared with curve (a ) .

DISCUSSION

The inc rease in the Liquid l imit of i l l i te, produced by increasing the s ize of the adsorbed monovalent cation has been descr ibed by Rosenqvist, 1957. The resu l ts of h is tes ts on both i l l i te and monl- mor i l loni te a r e shown on Fig. 10. He re la tes the inc rease in liquid l imit to the increasing polarizabi l i ty of the cations a s their s ize inc reases . The Iarge cations a r e m o r e easi ly d istor ted into an induced dipole by

by the force f ields between the clay par t ic lee, than the smal le r cations.

Rosenqvist, 1955, and Moum and Rosenqvist, 1961, suggest that the polarizable cations induce an inc reased at t ract ion between part ic les. More water would, therefore, be requi red in a potassium clay to reduce the in terpar t ic le fo rces to the s a m e Level a s in a sodium clay. If we assume that the net fo rces at the liquid l imit a r e the s a m e in Na and K clays (i. e. they have the same strength) , the K clay wil l have the higher mo is tu re content (higher Liquid l imit).

Another equally plausible explanation i s that the sodium cation, which has a higher ionic potential and a la rger hydrated radius than potassium, may have a lubricat ing effect on the soi l system. The la rger s ize of the hydrated sodium ions may prevent the clay par t ic les f rom approaching a s c lose to one another thus lowering the fo rces of at t ract ion and reducing the shear strength of the clay at a given water content.

Moum and Rosenqvist, 1961, explain the shape of the montmori l lonite curve in Fig. 10 a s being a function of the amount of in ter layer ( infracrystal l ine) water. F o r K, Rb and C the amount

B of in ter layer water i s about the s a m e s o that the liquid l imit i s a stra ight line function of the log polarizabi l i ty a s in i l l i te. On the other hand Li and Na absorb a great deal of water because they have very high ionic potentials. Th is gives these cations ve ry large hydrated radius and the montmori l lonite swells to Large "d" values. In other words, the montmori l lonite swells until i t contains a great deal of in ter layer water which i s represented by the hatched a r e a in Fig. 10.

A "beidellite" montmori l lonite f r o m Cali fornia, saturated with Na and K, gave resu l ts s im i la r to Rosenqvist 's montmori l lonite. The i l l i te clay studied he re , despite a smal l content of col lapsible ve rm i - cul i te, behaved like Rosenqvist 's i l l i tes.

Moum and Rosenqvist, 1961, a lso descr ibe a group of exper iments designed to study the ef fects of in ter layer water and in terpar t ic le water on the shear strength of sodium and potassium clays. I l l i tes and montmori l loni tes, ar t i f ic ia l ly sedimented and consolidated in 35 par t s per thousand NaCl, we re subjected to KC1 leaching for a per iod of 26 months before strength testing. The i l l i tes which were Leached

with KCL had undrained strengths about 1. 6 t imes grea ter than the corresponding Na i l l i tes a t given consolidation p ressu res . The dif ferences in proper t ies once again were explained in t e r m s of the polarizabil i ty of the adsorbed cations. With the m o r e polar izable potassium ion p resent , the at t ract ive fo rces and bonds between the clay par t ic les of the. f locculated system a r e increased.

The resu l ts of the consolidation fabr ic studies can be explained by e i ther Rosenqvist 's concepts of cation polarizabi l i ty or by concepts of ionic potential and the s ize of the adsorbed hydrated cations. The K clays were certain ly m o r e res is tant to compress ion a s indicated by both the consolidation curves and the x - ray fabr ic study. The drained strength resu l ts a lso a r e readi ly explained by ei ther concept. Very l i tt le dif ference was observed in the undrained strengths of the Na and K i l l i te studied here . The reason i s probably the very different s t r e s s history of samples. The clays tested by Moum and Rosenqvist were leached af ter consolidation whereas those tested he re were leached and then consolidated.

CONCLUSIONS

1. The clay soi l tested consisted of i l l i te with up to 30 p e r cent of vermicul i te and chlori t ized vermicul i te.

2. Different engineering proper t ies were obtained on the clay, depending on whether Na o r K was the adsorbed cation. In genera l , the K clays were stronger and m o r e res is tant to consolidation than the Na clays.

3. An x - ray fabr ic study on consolidated clay samples showed that the KCL leached clays had a m o r e flocculated o r open s t ruc tu re than the NaCl leached clays. In other words , the Na clays had developed m o r e para l le l ism during consolidation than the K clays.

4. The engineering test resu l ts and the fabr ic data may be explained in t e r m s of Rosenqvist 's concepts of cation polarizabi l i ty o r in t e r m s of ionic potential and the s ize of the hydrated rad i i of the adsorbed cations.

5. Continuous sa l t water leaching removed some of the complex aluminum and i ron hydroxide cations adsorbed on the clay, result ing

i n i n c r e a s e s i n the cat ion exchange capaci ty and changes i n the so i l p roper t ies . Cons iderab le chemica l cont ro l is r equ i r ed in a l l long- term tes t s on c lay so i l s i n o r d e r to i n t e rp re t the engineer ing tes t r e s u l t s .

6. The resu l t s of the p re l im ina ry fab r i c study desc r i bed h e r e suggest that x - r a y techniques could become a v e r y usefu l tool i n measu r i ng the ave rage pa r t i c l e a r r a n g e m e n t s of the c lay p la te le ts in a so i l m a s s .

REFERENCES

L. J. B j e r r u m - Soi l Seminar S e r i e s ; Massachuse t t s Inst i tu te of Technology, Spr ing 1961.

J. Moum and I. Th. Rosenqv is t - The Mechanica l P r o p e r t i e s of Montmor i l loni t ic and I l l i t ic C lays Rela ted to the E lec t ro l y tes of the P o r e Wate r ; P r o c . 5th Int. Conf. on Soi l Mech. and Fdn. Eng . , Vol. 1 , pp. 263-267, 1961.

M. C. P o w e r s - Adjus tment of Land Der ived C lays to the Mar i ne Environment; Jou r . Sed. Pe t ro logy , Vol. 27, pp. 355-372, 1957.

R. M. Quigley - R e s e a r c h on the Phys i ca l P r o p e r t ies of Ma r i ne Soi ls ; Massachuse t ts Ins t i tu te of Technology, Soi l Eng ineer ing Div is ion, Publ . 117, 1961.

and R. T. Mar t in - Chlor i t i zed Weather ing P r o d u c t s of a New England Glac ia l T i l l , Clays and Clay M inera ls ; 10th Confa 1961, In p r e s s ; Massachuse t ts Inst i tu te of Technology, Soi l Eng. Div. Publ . 119, 1961.

I . Th. Rosenqvist - Invest igat ions i n the Clay-E lec t ro ly te-Water Sys tem; Norwegian Geotech. Inst . Pub l . 9 , 1955.

- Discuss ion, P r o c . 4th Int. Conf. on So i l Mechs. and Fdn. Eng. , Vol. 111, pp. 257-258, 1957.

8. C. E . Weaver - Geologic In terpreta t ion of Argi l laceous Sediments; Bull. Arner. Assoc. Pe t ro leum Geol. , Vol. 42, pp. 254-271, 1958a

9. - The Effects and Geologic Signif icance of Po tass ium Fixat ion by Expandable Clay Minera ls Der ived f r o m Muscovi te, Biot i te, Chlor i te and Volcanic Mater ia l ; A m e r . Minera log is t , Vol. 43, pp. 839-861, 1958b.

10. A. E. Z. Wissa - A Study of the Ef fects of Environmental Changes on the S t ress -S t ra in P rope r t i es of Kaol ini te, S . M. T h e s i s , Mass . Inst. of Technology, 1961.

SCIL jES; i i ,PT

E:~,',ALE',~ CFAlr; SIZE c0 4 r.!ICRmS C '.E Fqcr r :Y , F4CM T u E " A b&D ' 0 . nCiRlLONS 3F A HEATWERED T I L L C C h : a S I r I m IL:.rE. VEQH~CULITE

S W E L L I N G CLAY. rVd C n L w l r E

X-RAY DIFFRACTION TSACE M21, BATCH 3 USED FOR ENGINEERING TESTS

CENTRIFUGE ORIENTED 9 2 - - 1 1

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4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 4 4

FIGURE 1

DEGREES 2 8

VERTICAL CONSOL IDATION PRESSURE (psf 1 FIGURE 3

DRAINED SHEAR STRENGTH (psf )

FIGURE 5 ,

- -

(001 ( 002 ) 72; 4 ( h k l ) 4 3.6

( 0 0 3 1

Rondom 2 .4 i (

Cd 1 I I I I I I 1-

8 I0 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 DEGREES 2 0

FIGURE 6

J L

1 r I 1 1 1 1 I I 1 I I I I I

X-RAY DIFFRACTION PATTERNS OF KAOLINITE SHOWING DEGREE OF PARTICLE ORIENTATION

(001 1 7.2

( 002 ) 4 3.6 % 0) Dispersed, centrifuged on porous

plote 15 min at 2,000 r pm

b ) X-royed surfoce of cloy cut from foilure plone of o test specimen. ie, surface In plane of movement.

c) Floculoted koolin from same somple as ( b ) but outside of foilure zone

d) Rondom, powder pottern Powder sprinkled on plote and X-royed

( 0 0 3 1 2411 4

( 0 )

tb)

Semi - porol le l

/ C

Porollel

FIGURE 8

/"\ 'a, PEAK (003)

7; VERMICULITE AND CHLORITE PEAK (002)

BOTTOM M l D- L- *- --

TOP

w = 65 7 O/O u = 66 0 O/O u.66 7 5 %

D~rect shear 13 V, = 3000 psf Z = 1276 P S ~

See note In text Re vo te r content

So11 : M21, Botch 3 < 0.4 mlcrons Pore fluld 9 OIo0 NaCl

PARTICLE ORIENTATION WITHIN A SHEARED DRAINED DIRECT SHEAR SAMPLE (SAMPLE AIR DRIED t3tFORE X-RAY)

I I 0 I 2 3 4

SCALE IN MILLIMETERS

ic TOWARDS FAILURE ZONE

FIGURE 9 CHANGE IN PARTICLE ORIENTATION AS A RESULT OF SHEARING ACTION

MEASUREMENT O F SHEAR STRENGTH, PLASTICITY AND WATER RETENTION O F CLAYS RELATED T O INTERPARTICLE FORCES

B. P. Warkent in

SUMMARY

The act ion of f o r c e s between c lay pa r t i c l es can expla in the behaviour of so i l s in ce r t a i n eng ineer ing appl icat ions. These f o r c e s a r e assoc ia ted with the high s u r f a c e a r e a and e l ec t r i c charge of c l ays , and thei r act ion depends upon the composi t ion and a r rangemen t of the par t i c Les and upon the p o r e f luid. In natura l ly occu r r i ng so i l s , any quant i tat ive mani fes ta t ion of these f o r c e s i s poor ly understood. In this paper s e v e r a l examp les a r e chosen f r o m recen t m e a s u r e m e n t s on remoulded samp les of wel l-def ined c Lay m i n e r a l s to show how eng ineer - ing p roper t ies of c lays can be in te rp re ted on the b a s i s of i n t e rpa r t i c l e f o r ces .

Montmor i l loni te c lay can take up cons iderab le amounts of water on swel l ing and re ta i n i t s s t reng th , whe reas a kaol in i te samp le wi l l fa l l apa r t . Th is d i f fe rence i s not s imply re la ted to f o r c e s of a t t rac t ion ; the s t reng th of montmor i l lon i te i n c r e a s e s a s the f o r ce of repu ls ion i nc reases . Measu red shea r s t reng ths of pu re c lays a r e given and in te rp re ted on the bas i s of the f o r c e s requ i red to move pa r t i c l es in the fa i l u re plane. F o r montmor i l lon i te th is movement i s r e s i s t e d by in te rpar t i c le repuls ion; fo r kaol in i te the f o r c e s of a t t rac t ion depending upon acid i ty and sa l t contentrat ion a r e impor tant .

The Liquid l im i ts of these c lays a r e a l s o in te rp re ted f r o m the dominant i n te rpar t i c le f o r ces .

F o r c lays which on dry ing sh r ink , with no i n c r e a s e i n a i r - f i l led vo ids , wa te r i s re ta ined by the s a m e f o r c e s which cause swel l ing, The mechan i sm of wa te r re tent ion i s of i n t e res t when the pr inc ip le of effect ive s t r e s s e s i s appl ied whe re m e a s u r e d p o r e wa te r p r e s s u r e s a r e

negative. Experimentally measured water retention curves for clays a r e compared with calculated swelling pressure to show the contri- bution of interpart icle repulsion and attraction to water retention.

The behaviour of clay soi ls i s determined by forces acting between clay part icles. This action can be through the water layers intimately held at the part icle surfaces through the diffuse layer of exchangeable cations, o r in some cases d i rect part icle contact. Forces between part ic les of clay size a r e studied within the discipline of physical chemistry; hence one speaks of these interpart ic le forces a s physico-chemical forces. Interpart icle forces in clays a r i se f rom the high surface a r e a which actively absorbs water and organic molecules, f rom the electr ic charge which at t racts and holds the exchangeable cations, and from inter-atomic forces.

Many recent studies have shown the influence of part icle arrangement on engineering behaviour of clay soi ls (1) and methods have been devised for i t s measurement (2 ) although quantitative specification is difficult. This part icle arrangement i s the resul t of the action of interpart ic Le forces. In sedimented clays, arrangement is the resul t of interpart icle forces determined by the environment, e. g. concentration of salt in the water in which the clays were deposited determines whether they will have a flocculated or a dispersed part icle arrangement.

Interpart icle forces in clays a r e not completely under - stood. There i s considerable qualitative information on how certain clays react to given empir ical measurements, e. g. amount of swelling and the swelling pressure , and a qualitative and descript ive understanding of the nature of the forces which must be responsible. Fo r some pure clays, the swelling pressure can be derived f rom the fo rces of repulsion (3)

Forces of attraction betwe.en part ic les, which a r e of mo re importance than forces of repulsion in engineering behaviour,

a r e m o r e diff icult to specify. Often they r esu l t f r o m inorgan ic o r o rgan ic " impur i t ies" which bond one par t i c le to ano the r . In na tu ra l

so i l s , which often conta in .-i m i x t u r e of c lay m i n e r a l s a s we l l a s these " impur i t ies" which r e a c t with the m i n e r a l s , a quant i ta t ive speci f icat ion of f o r ces h a s r a r e l y been ach ieved, and o f ten even a qua l i ta t ive under - standing of the i r behaviour i n t e r m s of the contro l l ing i n t e rpa r t i c l e f o r c e s is lacking.

In view of these d i f f i cu l t ies and uncer ta in t i es , s e v e r a l approaches to the p rob lem of i n t e rpa r t i c l e f o r c e s i n eng ineer ing behaviour a r e poss ib le but none of these a lone i s fully sa t i s fac to ry o r a l l - i nc lus i ve . The work in the Soi l Mechan ics Labora to ry a t McGil l Un ivers i ty commenced s e v e r a l y e a r s ago using p repa red samp les of pu re c lay m i n e r a l s f o r which some in format ion on i n t e rpa r t i c l e f o r c e s w a s avai lable. The eng ineer ing p rope r t i es of these c lays w e r e m e a s u r e d and then re la ted to i n t e rpa r t i c le f o r c e s to s e e in what way these f o r c e s w e r e man i fes ted i n eng ineer ing behaviour . It h a s been found that such a re la t ionsh ip can often be es tab l i shed , but i t i s not s imp le o r s t ra igh t fo rward .

Th is work i s pa r t of a continuing p r o g r a m i n the Depar t - men t of Civi l Eng ineer ing , under the d i rec t ion of P r o f . R. Yong, and the author . Th i s paper wi l l d i s cuss s o m e of the r e s u l t s obtained i n the study to i l l u s t r a t e what i s be ing Learned f r o m m e a s u r e m e n t s on p u r e , espec ia l ly p repa red samp les of c lay m i n e r a l s .

RESULTS AND DISCUSSION

Shea r St rength

Measu remen ts of r es i s t ance to d i r ec t , t r ans l a to r y shea r w e r e m a d e on samp les of c lays p r e p a r e d to have d i f fe rences i n i n t e rpa r t i c l e f o r ces . Shea r s t reng th was then re la ted to the i n t e rpa r t i c l e f o r ces . Because of the uncer ta in ty of i n te rp re t ing d i r ec t s h e a r va l ues , no re l i ance was p laced upon the p r e c i s e va lues obtained, However , the d i f fe rences i n m e a s u r e d va lues with changes i n i n t e rpa r t i c l e f o r c e s a r e fe l t to be re levant . An account of the exper imen ta l me thods and i n t e r - p re ta t ion of r e s u l t s has been publ ished (4 ) .

It h a s been poss ib le to del ineate the i n t e rpa r t i c l e f o r c e s respons ib le fo r s h e a r s t reng th i n ce r t a i n c lays and to se t up a

model, but the shea r strength is not simply re lated to fo rces of a t t ract ion minus repulsion. Swelling and non-swell ing c lays ac t differently. Swelling c lays - where repuls ion can be the dominant in terpar t ic le f o r ce - re ta in strength even when wet. When non- swell ing c lays a r e wetted to the s a m e water content, the samples fa l l apar t . This dif ference is apparent in the marked tendency fo r non- sw elling c lays such as kaol ini te to e rode under moving water.

F igure 1 shows the shear strength va lues measu red for sodium montmori l loni te, a high- swell ing c lay, a t di f ferent void ra t ios and a t two sal t concentrat ions. At the higher sal t concentrat ion, 1. OM NaC1, in terpar t ic le repuls ion i s lower, a t t ract ion is higher and shear strength is lower. In F igure 2 , calc ium montmori l loni te with a lower swell ing ( lower net repulsion) and higher a t t ract ion, has the lower shear strength at the same void ra t io o r s a m e average in terpar t ic le distance. In a l l of these measu remen ts , shear strength i nc reases a s net repulsion inc reases . Th is i nc rease in repulsion i s accompanied by an inc rease in so i l suction ( s e e sect ion on water retent ion), so that a g rea te r strength would be predicted f rom effective s t r e s s e s . However, this does not explain the existence of shear strength in a clay where the swell ing shows that a net repuls ion between par t ic les exists.

During shea r , par t i c les in the fa i lu re plane become or iented para l le l to each other , and any fo rce res is t ing this orientat ion should contr ibute to shear s t rength of remoulded clays. F igure 3 suggests how in terpar t ic le repulsion can play this ro le for high- swell ing c lays. Format ion of the fa i lure plane requ i res par t ic le movement , in some p laces the c loser approach of one par t ic le to another. In terpar t ic le repulsion r e s i s t s this movement, accounting qualitatively fo r measu red strength values. It is diff icult to apply this concept quantitatively because par t ic le orientat ion i s unknown and changes a s void ra t io changes, becoming m o r e para l le l as the void ra t io dec reases . There fo re , while net repuls ion can be measu red (as the swell ing p r e s s u r e ) , the amount of movement requi red can not b e specified.

F r o m the model i t may be predicted that shear strength would be lower for a m o r e para l le l par t ic le orientat ion. Support for this concept was obtained i n the author 's Laboratory f r o m measurement ( i n a modified way) of the liquid l imit of a sample with para l le l par t ic le orientat ion and one with random orientation. At the s a m e water content, the sample with para l le l or ientat ion requi red fewer blows to c lose the

groove. The test was not repeated, and i t i s not known whether a l l other fac tors were constant.

F igure 4 shows measu red shear strength values for kaol ini te, a low-swelling clay. Highest shear strength was measured for the flocculated c lay, where at t ract ion i s the dominant in terpar t ic le force. The d ispersed c lay, with net repuls ion, had lower strength a t the same void rat io. Interpart ic le fo rces were s t i l l important in determining shear strength, a s shown by the low values fo r the coa rse f ract ion of the clay.

The fo rces of a t t ract ion between par t ic les involved in f locculat ion a r e not sufficiently strong to c ontribute appreciably to shear strength in a d i rect way, i. e. in res is t ing separat ion of par t ic les . Interpart ic le at t ract ion could keep the par t ic les in a cer ta in or ientat ion, contributing to strength by res is t ing the rear rangement requi red to fo rm a fa i lure plane. If the flocculated s t ruc tu re i s visual ized a s a random arrangement of par t ic les with face-to- face and edge-to-face contacts, fo rces of a t t ract ion would res i s t the rear rangement to para l le l or ientat ion. In the d ispersed c lay, repulsion keeps the par t ic les in a n ar rangement which i s m o r e near ly para l le l to begin with, requir ing less force and less movement f o r rear rangement in the fa i lure plane.

The measu remen ts d iscussed above a r e representat ive of the resu l ts obtained in this study. Taking a l l the work into considerat ion, i t i s concluded that shear strength can be in terpreted on the bas is of in terpar t ic le f o r ces for remoulded c lays and that these fo rces lead to a specific par t ic le ar rangement and stabi l i ty of that a r rangement which accounts for res is tance to shear . This depends upon both the fo rce required to move par t ic les and the amount of movement in the fa i lure plane.

The resu l ts apply only to remoulded c lays; for undisturbed so i ls , fo rces of a t t ract ion due to in terpar t ic le cementat ion a r e often dominant. However, for c lays with sensit iv i ty values c lose to unity, these considerat ions a r e pert inent .

Liquid Limit

The upper p last ic l imi t , o r Liquid l imi t , i s general ly

i n te rp re ted a s the wa te r content just exceeding the amount of bound wa te r . Th i s s m a l l excess of f r e e wa te r a l lows the pa r t i c l es to m o v e pas t each o ther . The th ickness of the bound wa te r Layer i s i n f e r r ed f r o m the wa te r content a t the l iquid l imit and v a r i e s with the c lay and the exchangeable cat ion. Di f ferent exchangeable cat ions fa l l in a s e r i e s of i nc reas ing bound wa te r l aye r th ickness, but i t i s found that the s e r i e s does not r e m a i n the s a m e for d i f ferent c lays . F o r swel l ing c lays , monovalent exchangeable ions such a s sod ium give the h igher l iquid l im i t , whe reas f o r non- swel l ing c l ays , divalent ca lc ium o r t r i va lent a luminum give the h igher va lues . Measu remen ts w e r e , t he re fo re , m a d e of the liquid Limit f o r samp les f o r which i n t e rpa r t i c l e f o r c e s could b e spec i f ied to s e e whether p las t ic p rope r t i es could b e re la ted to t hese f o r c e s .

F o r th is i n te rp re ta t ion , i t h a s been found convenient to speak of a n " in teract ion volume" def ined a s that vo lume within which pa r t i c l es o r units of pa r t i c l es i n t e r f e re with the movement of ad jacent pa r t i c l es (5) . The i n t e rpa r t i c l e f o r ces de te rm in ing the in terac t ion volume m u s t then be speci f ied.

Measu red liquid l im i ts fo r montmor i l lon i te at d i f ferent sa l t concent ra t ions a r e shown i n F i g u r e 5. F o r sod ium montmor i l lon i te , i n te rpa r t i c le repu ls ion de te rm ines the in terac t ion volume. As repu ls ion i s dec reased by i nc reas i ng the sa l t concent ra t ion , in terac t ion vo lume and Liquid l imi t dec rease . Repuls ion keeps the pa r t i c l es f ixed at a ce r t a i n d i s tance f r o m each o ther and when th is repu ls ion i s d e c r e a s e d , the pa r t i c l es have a g r e a t e r f r eedom f o r movement . Subst i tut ing a divalent ion , ca lc ium, a l s o d e c r e a s e s repu ls ion and hence the liquid Limit. But i nc reas ing sa l t concentrat ion h a s been shown to lead to only a s m a l l d e c r e a s e in repu ls ion and i t d e c r e a s e s the Liquid Limit by only a s m a l l amount.

The dominant f o r c e in kaol in i te i s aga in i n t e rpa r t i c l e a t t rac t ion keeping the pa r t i c l es in a f ixed or ien ta t ion and defining the in terac t ion volume. The d i spe rsed kao l in i te , with m a x i m u m repu ls ion , h a s the Lowest l iquid Limit a t Low sa l t concent ra t ion i n F i g u r e 6. The pa r t i c l es a r e in m o r e near l y pa ra l l e l or ientat ion and s ince repu ls ion i s Low f o r the low-swel l ing c lay , the in terac t ion vo lume i s sma l l . The c lay with edge-to- face f locculat ion due to posi t ive cha rge on the edges and negat ive cha rge on the p lanar su r f aces , has the h ighest in terac t ion volume.

With increasing sal t concentrat ion, a l l samples change to a face-to-face s t ructure due to salt flocculation with an intermediate interaction volume.

The effect of exchangeable cations on liquid Limit of c lays can be understood f rom these resul ts . Fo r high-swelling c lays, polyvalent cations decrease repulsion and hence the liquid Limit; for low-swelling clays they inc rease flocculation and increase the interaction volume and liquid l imit. The dominant interpart ic le forces differ.

Water Retention

Interpart ic le forces a r e a lso involved in retention of water by clay soi ls. If the shrinkage on drying equals the volume of water lost , the clay remains water- saturated. However, the measured pore-water p ressu re would be negative and if the soi l were placed in contact with f r e e water it would take up water and increase in volume. Since effective s t r e s s e s a r e used in the analysis of strength of soi ls at these water contents, it i s of in terest to examine water retention m o r e closely.

The force that a dry soi l can exert in the absorption of water , measured a s the restraining force that must be exerted on the water to prevent movement, i s called soi l suction. Soil suction decreases a s the water content inc reases . This i s not a water tension a s the water i s not necessar i ly under tension or negative p ressu re equal to the value of the soi l suction. P o r e water p ressu re measured through a f ine porous stone a s a negative head of water may be equal to soi l suction but not necessar i ly equal to the p ressu re on the soi l water. To prevent confusion, it i s best to think in te rms of thermodynamics of a f r e e energy difference between the water in the soi l and f ree water.

Water retention fo rces in sands differ f rom those in clays. When a saturated sand Loses water , a i r en ters the voids. The p ressu re difference ac ross the curved a i r -water interface gives r i s e to capi l lary water retention and we speak of capi l lary fo rces . The force of retention, o r capi l lary r i s e , depends upon the s ize of voids.

In a clay soi l which i s water-saturated, there a r e no a i r -water interfaces and change in water content i s accompanied by a change in volume. The fo rce required to remove an increment of water i s that required to decrease the volume by that amount (assuming no

d i rec t in te rpar t i c le in ter ference) . This f o r ce i s equal to the swell ing p r e s s u r e (8). There fo re , making al lowance fo r units and d imens ions, the swell ing p r e s s u r e equals the f o r ce of water retent ion a t that wa te r content. One mechan ism fo r the swel l ing p r e s s u r e is the excess ion concentrat ion between clay par t i c les resu l t ing i n a n osmot ic gradient which causes water to move between the par t i c les . Swell ing p r e s s u r e is the p r e s s u r e necessa ry to prevent this water movement (6 ) .

The expected equivalence between swell ing and wate r retent ion has been checked for seve ra l c lays (7). The resu l t s shown in F igure 7 for one clay a r e representat ive. Measured swell ing p r e s s u r e s w e r e not avai lable for this clay; the calculated values w e r e obtained f r o m equations giving the ion concentrat ions around c lay par t i c les (7) . These calculat ions give only the repuls ion and a r e in e r r o r by the amount of f o r ces of a t t rac t ion between par t i c les .

Measured suct ion values a g r e e with calculated swell ing p r e s s u r e s fo r the s l u r r i ed sample down to p F 2. 5 o r about 300 cm. of water suction. The p F i s the logar i thm of the measu red so i l suct ion in cm. of wa te r . Eelow that , f o r ces of a t t rac t ion apparent ly prevent swell ing and uptake of a s much wate r a s predicted f r o m repulsion. These in te r - par t ic le a t t rac t ion f o r ces a r e impor tant in so i l s t r uc tu re and a r e being studied fu r ther . The swell ing p r e s s u r e overes t imates the water content of the undisturbed sample a t a l l suct ion values. F o r c e s of a t t rac t ion apparent ly operate over the en t i re range. These compar isons have indicated that in te rpar t i c le f o r ces account f o r water retent ion over pa r t of the suct ion range for the c lays studied.

P a r t i c l e a r rangement a l so inf luences water retent ion by c lays. High-swell ing c lays have the highest wa te r content for para l le l par t i c le or ientat ion but low- swell ing c lays have the highest water content f o r random ar rangement where ex t ra wate r beyond that involved in swell ing i s trapped between i r r egu la r l y a r ranged par t i c les o r aggregates of par t ic les . The high natura l wa te r content of Leda c lay , up to 7070, is due to the random par t i c le a r rangement . If the a r rangemen t i s d isturbed and the sample d r ied , the maximum water content d e c r e a s e s to about 3570.

Acknow ledement

Th is work was ca r r i ed out under the r e s e a r c h grants f r o m the National Resea rch Council whose ass is tance i s grateful ly acknowledged.

REFERENCES

1. T . W. Lambe - Compacted Clay: St ructure; T rans . Amer . Soc. Civil Eng ineers , Vol. 125, pp. 682-706, 1960.

2. J . K . Mitchel l - The Fabr ic of Natura l Clays and I ts Relat ion to Engineering P rope r t i es ; Highway R e s e a r c h Board P r o c . , Vol. 35, pp. 693-713, 1956.

3. B. P. Warkent in, G. H. Bolt and R. D. Mi l le r - Swell ing P r e s s u r e of Montmori l lonite; P r o c . Soil Sci . Soc. Amer . , Vol. 21, pp. 495-497, 1957.

4. and R. N. Yong - Sheaj Strength of Montmori l lonite and Kaolinite Related to In terpar t ic le F o r c e s ; Clays and Clay Minera ls , Pe rgamon P r e s s , Vol. 9 , pp. 210-218, 1962.

5. Interpretat ion of the Upper P las t i c L imi t of Clays; Nature, Vol. 190, pp. 287-288, 1961.

6. The Mechanism of Volume Change in Clays; P r o c . 12th Can. Soil Mech. C o d . , NRC, Tech. Memo. No. 59, 1958,

7. Water Retention and Swelling P r e s s u r e of Clay Soi ls , Can. Jour . Soil Sci. , Vol. 42, pp. 189-196, 1962.

8. R. K. Schofield - Suction in Swollen Clays; P o r e P r e s s u r e and Suction i n Soi ls , But terwor ths, London, pp. 59-60, 1960.

x - 0.01 N NaCl 0 - 1.0 N NaCl

V O I D R A T I O

Fig. 1 Measured shear strength of sodium montmori l lonite a t different sa l t concentrat ions in the pore water .

Q - Na- MONTMORILLONITE * -Ca- MONTMORLLONITE

5 K) 15 20 25 30 VOID R A T I O

Fig. 2 Measured shear strength of sodium and calc ium montmori l lonite.

I MECHANISM FOR SHEARING S T R E N G T H

I FAILURE PLANE

Fig. 3 Schematic d iagram for model of interact ing clay plates with in terpar t ic le repulsion res is t ing par t ic Le rearrangement during development of fa i lure plane.

a -DISPERSED 0 -FLOCCULATED

i -COARSE FRACTION L: \

VOI? R A T I O 1.3 Id

Fig . 4 Measu red s h e a r s t reng th of f loccu la ted and d i spe rsed kaol in i te and of c o a r s e kaol in i te .

1000

800-

600

400

200

0

-

3-0

-

- ,s- A

0 a

-

1 1 I I I m

0,001 0.0 1 0. I 1 .O 5.0 SALT CONCENTRATION - M

F ig . 5 Measured water content a t the liquid Limit f o r montmor i l lon i te

c lays (0-Sodium Montmor i l lon i te f NaCL; X- Calc ium Montmor i l lon i te + CaCL ). 2

S A L T CONCENTRATION - M

F i g . 6 Liquid Limit of kao l in i te s a m p l e s wi th d i f f e ren t i n t e r p a r t i c l e f o r c e s (0 -F loccu la ted , edge- to - face a t pH 4 , with addi t ion of C a C l ; - ~ l ~ ~ ~ ~ ~ ~ t ~ d a t pH 6 , with addi t ion of CaC l X - D i s p e r s e d a t pH 10, wit add i t ion of NaC 1). 2 ; t

WEALD CLAY

'+. +.*

\ *.,

\

\ . - \ I . I

UNSAT'N \NATURAL SLURRIED

BEGINS I t . I . . .

eo 40 60 8 G

WATER ConTEnT N

Fig. 7 Measured water retention and calculated swelling pressure for Weald clay. (Water retention values from Croney et al , 1953) .

HEAVE O F SPILLWAY STRUCTURES ON CLAY SHALES

by

R. Peterson and N. Pete rs

Spillways constructed on clay shale in Western Canada have heaved considerably. This paper briefly descr ibes the clay shales of the a rea and gives typical laboratory swelling test resul ts. It has not yet been possible to predict total heave and ra te of heave f rom laboratory tests. Observational programs to check the performance of existing structures a s well a s special tests were undertaken to provide information required for design. Typical heave observations a t spillways showing the effect of seepage, f rost action, and hold-down piles a r e included.

* Summary prepared by authors.

Note: Paper published in fu l l in the Canadian Geotechnical Journal, Vol. I , No. 1, September 1963.

VOLUME CHANGES IN UNDISTURBED CLAY PROFILES IN WESTERN CANADA

J. J. Hamil ton

As par t of an overa l l study of the per fo rmance of building foundations in highly p last ic so i l a r e a s of Weste rn Canada, the Division of Building Resea rch has been measur ing ground movements and changes in soi l mo i s tu re conditions in g r a s s -covered, undisturbed so i l prof i les under c l imat ic conditions ranging f r o m sub-humid to semi -a r id . Resul ts of measurements begun in 1951 in Winnipeg, Manitoba, and m o r e recent ly those in Regina, Eston and T isda le , Saskatchewan, a r e repor ted. Resul ts of a theoret ical soi l mo is tu re depletion calculat ion, based on Thornthwaite' s potent ial evapotranspirat ion concept, a r e presented. It i s proposed a s a m o r e ra t iona l way of measur ing the vegetat ion- c l imate fac tor in humid to sub-humid c l imates than s imply compar ing a i r tempera tu re and precip i tat ion with long-term averages . Empi r i ca l re lat ionships a r e suggested between calculated soi l mo is tu re depletion, the depth of f r e e water table, and the depth of f ros t penetrat ion under s im i l a r therma l conditions but di f ferent soi l mo is tu re conditions. In si tu shr inkage of undisturbed, unsaturated so i l s a t tempera tu res well

0 below 32 F has been observed and i s at t r ibuted to therma l a i r -vo id volume change.

* Summary p repared by author.

Note: P a p e r published in fu l l in the Canadian Geotechnical Journa l , Vol. I , No. 1, September 1963.

- 6 1 -

PRACTICAL EXPERIENCE WITH HIGHLY SWELLING SOIL TYPES

by

A. 0. Dyregrov and R. M. Hardy

* SUMMARY

The prob lem of the effect of swell ing so i l on buildings with shallow foundations, on the stabi l i ty of s lopes, and on roads and runways, i s of considerable impor tance in a r e a s of recent g lacia l lake deposi ts in Western Canada. It is thought that the physico-chemical nature of the swell ing p r e s s u r e tends to reduce the effect ive s t r e s s but i s not ref lected i n the pore p r e s s u r e in the water phase of the soil. The suggestion i s made that the effective s t r e s s be calculated by subtract ing the pore p r e s s u r e f r o m the total s t r e s s i n the usual way and in addit ion P , the swell ing p r e s s u r e , should a l so be subtracted.

S F r o m a pract ica l point of view, this t e r m should be calculated f r o m f ree-swe l l consolidation tes ts ra ther than constant volume test .

:F Summary p repared by E . Penne r .

Note: Pape r submitted f o r publication to the EIC.

PHYSICOCHEMICAL PHENOMENA IN SOIL MATERIALS

by

S. Pawluk

P a r t i c l e s ize dist r ibut ion of soi l separa tes fa l l s essent ia l ly into th ree bas ic groups, sands, s i l t s , and c lays, the s ize distr ibut ion l imi ts of which rernain cont rovers ia l among the var ious scient i f ic groups in te res ted in their study. Soi l sc ient is ts have for a long t ime accepted the division between clay and c o a r s e r f rac t ions a s 2 mic rons , s ince, in genera l , i t i s the f rac t ion l ess than 2 microns in s i ze that contains clay m ine ra l s which exhibit physico-chemical mani festat ions re la ted to colloidal behaviour.

Among the var ious physico-chemical fea tu res observable, the mos t signif icant a r e those re la ted to ion exchange phenomenon and water adsorpt ion. It i s these fac to rs which a r e responsib le for many of the anomal ies observed when studying so i l ma te r i a l s f r om a purely physical point of view.

Ion adsorpt ion and exchange phenomena charac te r i s t i c of colloidal clay m ine ra l s resu l t f r om the fundamental nature of their s t ruc tu ra l units in which isomorphous subst i tut ion, broken bonds on c r ys ta l edges, and exposed hydroxyl groups play a n essen t ia l par t . The resul t ing effect of these s t ruc tu ra l charac te r i s t i cs is the p resence of a net negative charge at the colloidal su r faces capable of preferent ia l ly a t t rac t ing posit ively charged genenions a s wel l a s polar solvents, such a s wa te r , when placed in aqueous electro lyte solutions.

* Summary p repared by author.

Note: P a p e r submitted for publication to the EIC.

SURFICIAL DEPOSITS O F ALBERTA

by

C. P. Gravenor and L. A. Bayrock

The sur f ic ia l deposi ts of cen t ra l and southern A Lberta have been under study intermit tent ly for some seventy-f ive yea rs . Most of the ear l y work was confined to the examinat ion of sect ions along the ma jo r r i v e r cou rses and to broad reconnaissance studies. Af ter the Second World War detai led mapping of the su r f i c ia l depos i ts of Alberta was s ta r ted by the Geological Survey of Canada and the Resea rch Council of A lber ta . To date, approximately 40,000 squa re m i l es of cen t ra l and southern A lber ta have been mapped in detai l . In addit ion, the Resea rch Council of A lber ta has mapped about 60,000 square m i l e s of no r thern A lber ta over the past four y e a r s by means of hel icopter surveys. Thus , roughly forty pe r cent of the su r face deposi ts of the Prov ince have been mapped. The hel icopter p rog ram to m a p the a r e a north of f i f ty-seven degrees latitude wi l l be completed this year and i t i s ant ic ipated that about one-half of the Prov ince wi l l have been mapped by 1963.

Detai led so i l m a p s cover ing pa r t s of the P e a c e R iver Country, cen t ra l and southern A lber ta , and reconnaissance m a p s of nor thern A lber ta have been p repared by the A lber ta Soi l Survey. Although in some cases the nomencla ture used by so i l sc ient is ts f o r the parent m a t e r i a l s of the so i ls is not ident ical with that used by geologists, these m a p s a r e never the less ex t reme ly useful to the geologist and provide an excel lent background f o r detai led geological study of su r f i c ia l ma te r i a l s .

Th is paper is designed to provide a general ized p ic ture of the nature and dist r ibut ion of the sur f ic ia l depos i ts of Alberta. Pa r t i cu la r attent ion wil l be given to a descr ip t ion of bur ied channels which m a r k the location of the dra inage sys tem which existed in A lber ta p r i o r to glaciation.

*summary p repared by author.

Note: P a p e r submit ted f o r publication to the Canadian Geotechnical Journal .

ENGINEERING ASPECTS O F THE GREAT SLAVE RAILWAY

by

J. L. Char les , V. R . Cox and F. L. Peckover

The 430 m i l e rai lway l ine running f r o m P e a c e River to Hay River with a branch Line to P ine Point Mines, 50 m i l e s eas t of Hay R iver , i s scheduled for completion by December 1965. The geology of the route and the nature of the t e r ra in i s descr ibed a s wel l a s how this knowledge was uti l ized in c i rcumvent ing difficult engineering prob lems. The route i s Located in an a r e a of extensive muskeg t r a v e r s e the southern f r inge of the permaf ros t region but no Large a r e a s of permaf ros t have been encountered.

* Summary p repared by E . Penner .

Note: P a p e r submitted f o r publication to the EIC.

PRELIMINARY SOIL MECHANICS ASPECTS O F THE RED RIVER FLOODWAY

by

J . Mishtak

Winnipeg, si tuated a t the confluence of the Red and As siniboine R ivers , has been plagued by floods of large magnitude s ince 1826. Subsequent large floods occur red i n 1852, 1861, 1916, 1948 and 1950. The flood of 1950 caused such seve re damage a s to st imulate posit ive act ion towards al leviat ion of the flood problem. As a resu l t , the Dominion Government se t up the Red River Bas in Investi- gation, whose purpose was to investigate var ious possibi l i t ies of al leviat ing flooding. Subsequently, the Royal Commission on Flood Cost Benefit was se t up to select the most economically feas ib le combination of schemes submitted by the Red River Bas in Investigation. The resu l t was the select ion of a d ivers ion channel bypassing the Grea te r Winnipeg a r e a in a combination with severa l other pro jects . Studies by the Water Control and Conservation Branch of the Prov ince of Manitoba resul ted in the relocations of the divers ion channel f r o m the a l ternat ive recommended by the Red River Bas in Investigation. This d ivers ion channel i s known a s the Red River Floodway.

The Red River Floodway wil l be about 30 mi les long, with a top width of 1 ,000 ft and an average depth of 30 f t . The quantity of excavations i s some 100 mi l l ion cubic yards . I ts design capacity of flow i s 60,003 cfs.

The soi l to be excavated i s a highly p last ic clay of glacial Lake Agassiz underlain by glacial t i l l . The ma in design prob lem of the channel was the select ion of s lopes which would be stable a lmost indefinitely. Other prob lems involved the effect of rebound on excavated g rades , eros ion, embankment composit ion, methods of excavation, ground- water seepage during excavation, depletion of local groundwater suppl ies and foundation of s t ruc tu res .

* Summary p repared by E. Penner .

Note: Pape r submitted fo r publication to the Canadian Ceotechnical Joarna l .

rHE MICA CREEK PROJECT - FOUNDATIONS AND MATERIAL INVESTIGATION

by

W. P. H a r land

* SUMMARY

This p rs jec t is a par t of the proposed power develop- ment of the Columbia R iver and i s Located between Golden and Revelstoke where the r i v e r has i ts steepest gradient of 1000 f t pe r 200 m i l es . In addit ion to descr ib ing the select ion of the s i te , the geology of the a r e a i s d iscussed in some detai l based on the foundation invest igat ions. To date , about 4 mi les of diamond dr i l l ing in bedrock and overburden have been completed. Two ma jo r so i l types f i l l the m a i n bedrock channel; dense glacial t i l l and a deposit of sand and g rave l with vary ing proport ions of boulders. It is bel ieved that a high f i l l - type dam a t Mica Creek. h a s been shown to be feasib le based on foundation conditions and the availabil i ty of suitable f i l l and other m a t e r i a l required.

* Summary p repared by E. Penne r .

Note: P a p e r submitted f o r publication to the EIC.

FOUNDATION TREATMENT AND CONSTRUCTION O F SIXTEEN MILES O F DYKE AT MANITOBA HYDRO'S GRAND RAPIDS PROJECT

J. R. Ret t ie , A. Koropatnick and W . S. I som

SUMMARY

The p ro jec t , now in i t s second yea r of const ruc t ion , i s Located a t the mouth ~f the Saskatchewan R ive r whe re i t f lows into Lake Winnipeg, 250 m i l e s nor th of the City of Winnipeg. The a r e a has been glac iated, is under la in with f ragmenta l and m a s s i v e l imestone, dolomite depos i ts of the Pa laeozo ic age and i s covered with numerous sink holes. The ex tens ive grout ing and foundation t rea tment requ i red to prevent leaking f r o m the r e s e r v o i r is descr ibed in deta i l , a s i s the des ign and const ruc t ion of the 16 m i l e s of dyke necessa ry to enc lose the forebay. The outstanding f ea tu re of the pro jec t i s the la rge grout ing operat ion m a d e n e c e s s a r y by the foundation condit ion of the s i te .

* Summary p repa red by E. Penne r .

Note: P a p e r submit ted f o r publ icat ion to the EIC.

APPENDIX "A"

REGISTRATION LIST

Norman J. All ison, 8714 - 120 S t ree t , Edmonton, Alberta.

Ralph Al lman, 15410 - 7 5 Avenue, Edmonton, Alberta.

Allan H. Anderson, 6741 Linden Avenue, South Burnaby, B. C.

K. 0 . Anderson, Department of Civil Engineer ing, Universi ty of A lber ta , Edmonton, Alberta.

Ralph W. Ansley, 8715 - 120 S t ree t , Edmonton, Alberta.

W. J. Aspinal l , 179 Hast ings Bay, Winnipeg, Manitoba.

D. G. Bacon, Drawer 460, F e r n i e , B. C.

Ian Bain, 1542 Kent Avenue, P o r t Coquitlam, B. C.

H. T. B e a r e , Suff ield Exper imenta l Stat ion, Ralston, Alberta.

R. P. Benson, Box 340, F o r t St. John, B . C.

Ar thur J. Bergan, 5 F r a s e r C rescen t , Saskatoon, Saskatchewan.

G. W. Berna rd , Be rna rd , Cur t i s & Hoggan, Edmonton, Alberta.

A lber t Eishop, 43 F a y Road, Calgary , Alberta.

T. Bishop, Dominion Br idge Co. Ltd. , Calgary , Alberta.

W. J. Blackstock, 35 Rosary Dr ive, Calgary , Alberta.

T. Blench, 9107 - 120 S t ree t , Edmo~l ton, Alberta.

M. Bozozuk, 691 Sandra Avenue, Ottawa, Ontar io.

T . J. Bradshaw, 11 139 - 87 Avenue, Edmonton, Alberta.

C. 0. Brawner , 399 1 Hol lydene, V ic tor ia , B. C.

P a u l A. Brozhu, 435 - 80 Avenue, Quebec 3 , P . Q.

A . A . Brown, 12'710 - 107 Avenue, Edmonton, Alberta.

C. H. Puck lee, 9035 - 145 S t ree t , Edmonton, Alberta.

W . G. H. Cam, 2998 Cadboro Bay Road, V ic tor ia , B. C.

Haro ld Cameron , 10516 - 53A Avenue, Edmonton, A lber ta .

L. A. Carey , 1 6 Hapbr ook P lace , Calgary , Alberta.

Br ig. J. P. C a r r i e r e , F rank i of Canada Ltd. , 187 Graham Blvd. , Town of Mount Royal, P. Q.

R. B. Car ru the rs , 10724 - 139 S t ree t , Edmonton, Alberta.

D. Cass-Beggs, Saskatchewan Power Corporat ion, Regin.3, Saskatchewan.

F r a n k M. Caza le t , 2997 West 39th Avenue, Vancouver, B. C.

J. L. Char les , 993A Grosvenor , Winnipeg, Manitoba.

E a r l A. Chr is t iansen, Saskatchewan Resea rch Counci l , Saskatoon, Sask.

J. G. C la rk , Mont rea l Engineer ing Co. Ltd. , P. 0. Box 250, P l a c e d t A r m e s , Montrea l , P. Q.

Rober t J. Conlon, 3027 Garden S t ree t , Niagara F a l l s , Ontar io.

V. R. Cox, P e a c e R iver , A lber ta .

C a r l B. Crawford, 198 Cluny S t ree t , Ottawa, Ontar io.

Michele P . Curc io, 11428 - 71 Avenue, Edmonton, A lber ta .

W . E . Cur t i s , B e r n a r d , Cur t is & Hoggan, Edmonton, A lber ta .

J. C. Dale, Canadian Ut i l i t ies L imi ted, Edmonton, Alberta.

Pau l Demcoe, 8515 - 142 S t ree t , Edmonton, Alberta.

Len Domaschuk, 1310 Ell iott S t ree t , Saskatoon, Sask.

P . J. Dowling, 10735 - 54 S t ree t , Edmonton, Alberta.

A. Dre imanis , Universi ty of Weste rn Ontar io, London, Ontario.

A. S. Dromlewicz, 8604 Elbow Dr ive, Calgary, Alberta.

Ray Dubas, 6820 - 105A St ree t , Edmonton, A lber ta .

A. 0. Dyregrov, 1495 Pembina Highway, Winnipeg, Manitoba.

W-. J. Eden, 8 50 Chapman B Lvd. , Ottawa 1 , Ontario.

C. N. E l l e r t , 10241 - 113 S t ree t , Edmonton, Alberta.

W. H. E l l i s , 826 ~ o l o n ~ s t r e e t , Saskatoon, Sask.

John A. Elson, Department of Geological Sc iences, McGill Univers i ty , Mont rea l , P. Q.

E. J. Evancoe, 328 - 42 S t ree t S. E . , Calgary , A lber ta .

George A. Faulder 14339 - 92A Avenue, Edmonton, Alberta.

I?. L. Fenwick, 13 - 37 S t ree t , Calgary , Alberta.

W. D. F inn, Department of Civil Engineer ing, Univers i ty of B r i t i sh Columbia, Vancouver 8 , B . C.

C. L. F i s h e r , A r m c o Drainage & Metal P roduc ts , Edmonton, Alberta.

W. FOSS, 628 - 20th S t ree t , Lethbr idge, A lber ta .

E. L. Fowle r , 7306 - 118A St ree t , Edmonton, Alberta.

L. A. F ra ik in , F rank i of Canada Ltd. , 197 Graham B lvd. , Town of Mount Royal , P. Q.

H. Glen Gi lchr is t , 2826 Angus S t ree t , Regina, Saskatchewan.

A. Grant , 712 Adamdell Crescen t , Eas t Kildonan, Manitoba.

G. V. Greenwood, P. 0. Box 4505, South Edmonton, Alberta.

Wayne H. Gri f f in, Box 7155, Eldorado, Sask.

R. Haas, 9418 - 66 Avenue, Edmonton, Alberta.

Arn i S . Hal ldorson, 4645 - 105A Avenue, Edmonton, Alberta.

A. E. Hamilton, P. 0 . Box 898, Banff , Alberta.

J. J. Hamilton, 43 Lindsay Dr ive, Saskatoon, Sask.

G. C. Hamil ton, 10970 - 138 S t ree t , Edmonton, Alberta.

S. J. Hampton, 87 35 S t ra thearn Crescen t , Edmonton, Alberta.

V. V. Hanna, 11 22 Frvntenac Avenue, Calgary, Alberta.

D. A. Hansen, 29 15 Champlain S t ree t , Calgary, A lber ta .

W . P . Har land, 17 10 Rosebery Avenue, West Vancouver, B. C.

Mur ray C. H a r r i s , 11 139 - 87 Avenue, Edmonton, Alberta.

W. E. Hawkins, 3924 - 36th Avenue S. W. , Calgary , Alberta.

R. A. Hemstock, 10 11 Royal Avenue, Calgary, Alberta.

Michael Hermansen, Ste. 9 , 26 Roslyn Road, Winnipeg 13, Manitoba.

Sydney F. Hi l l i s , 592 West 17th S t ree t , Vancouver, E . C.

F. A. Hlovosky, SuffieLd Exper imenta l Stat ion, Ralston, Alberta.

E . M. Hoy, 1426 Rivers ide Dr ive, North Vancouver, B. C.

Alan Insley, 860 Royal Oak, ,. Victor ia, E . C.

W.S. I som, Hybord, Manitoba.

Norman Iver son, P. F. R. A. , P. 0. Box 938, Saskatoon, Sask.

W . F. Iwanson, 10963 - 72nd Avenue, Edmonton, Alberta.

J . L . J a s p a r , P. F. R. A. , P. 0. Box 908, Saskatoon, Sask.

W . W . Jef f rey , 707 Fede ra l Building, Calgary , Alberta.

Verne C. Jones , Ste. 6, 9737 - 105th S t ree t , Edmonton, Alberta.

C. Ka rasek , 509 - 38 th Avenue S. W . , Calgary , Alberta.

Bernard Kathol, 10824 - 131st S t ree t , Edmonton, Alberta.

G. D. Kel lam,

2 ! 1 - 38th Avenue S. W . , Calgary, Alberta.

E. W . King, 8421 - 118th S t ree t , Edmonton, Alberta.

P. Koziki , 165 Card ina l C rescen t , Regina, Sask.

W. D. Kirk land, 11523 - 72nd Avenue, Edmonton, Alberta.

A. Koropatnick, Hybord, Manitoba.

N. D. Lea , 112 West Pender S t ree t , Vancouver, B. C.

W.S. Leggat, 5662 Cypress S t ree t , Vancouver, B. C.

K. M. L isse l l , P. F. R. A. , Cutbank, Sask.

K. Y . Lo, Ontar io Depar tment of Highways, Downsview, Ontario.

G. J. Locker , 11016 - 88th Avenue, Edmonton, Alberta.

W. C. Long, 2106 Ewar t Avenue, Saskatoon, Sask.

J. Longworth, 10828 - 67th Avenue, Edmonton, A lber ta .

John E. Lyle, 11638 - 74th Avenue, Edmonton, ALberta.

F. D. McCarthy, 97 15 - 60 Avenue, Edmonton, A lber ta .

J a m e s MacGregor , Univers i ty of A lber ta , Edmonton, Alberta.

G . MacLeod, 51 15 Keith Road, West Vancouver, B . C.

Ralph N. McManus, 10214 - 112 S t ree t , Edmonton, Alberta.

R. H. MacNeil l , 100 Highland Avenue, Wolfvi l le, N . S.

G. C. McRost ie, 393 Bel l S t ree t , Ottawa, Ontario.

Pau l Machibroda, 7 Ling S t ree t , Saskatoon, Sask.

E. I. Maduke, 10720 - 69th S t ree t , Edmonton, Alberta.

J . B. Mantle, 302 Main St reet Eas t , Saskatoon, Sask.

A. J. Marzocco, 5420 - 11A St ree t , Edmonton, Alberta.

W. H. Mathew s , 4170 Crown Crescen t , Vancouver, B. C.

M. A. J . Matich, 333 Dixon Road, Weston, Ontario.

G. G. Meyerhof, Nova Scotia Technical Col lege, Hal i fax, N. S.

B. W. Mickleborough, 646 Wil l iam Crescen t , Regina, Sask.

R. D. Mi les, 10611 - 74th S t ree t , Edmonton, Alberta.

V. Mil l igan, 1395 Devon Road, Oakvil le, Ontario.

Kenneth A . Mil l ions, 512 Banff Avenue, Banff, Alberta.

S.A. Mi lner , 10975 - 124th S t ree t , Edmonton, A lber ta .

John Mishtak, Room 408 Norquay Building, 401 Y ork Avenue, Winnipeg, Manitoba.

D. W. Mitchel l , Edmonton, Alberta.

C. Z . Monaghan, 10619 - 136th S t ree t , Edmonton, ALberta.

C. R. NeiLl, 6815 - 112 S t ree t , Edmonton, ALberta.

T . 0. Neuman, Northland Indust r ies Ltd. , 10040 - 104th S t ree t , Edmonton, Alberta.

C .A . Noble, 261 2 C ~ l m b e r Land Avenue, Saskatoon, Sask.

John E . Nuttall, 13712 - 122nd S t ree t , Edmonton, Alberta.

R. F. Ogilvy, ALuminum Company of Canada L td . , P. 0 . Pox 6090, Montreal 3, P. Q.

Lawrence 0. Olsen, 9675 - 102A Avenue, Edmonton, ALberta.

M. Olsen, 787 6 Gray Avenue, South Furnaby, B. C.

H. E. R. Ott ley, 8631 - 108A St ree t , Edmonton, Alberta.

Edmund P a r k e r , 340 Eas t Car isbrooke, North Vancouver, B. C.

L. E. P a r k e r , 396 Conifer S t r e e t , Sherwood P a r k , Alberta.

David J. P a r r y , 7 6 Cawder Dr ive, Calgary , ALberta.

F. W. Pa t te rson , 1569 Belmont Avenue, Niagara Fa l l s , Ontar io.

S. Pawluk, 6404 - 128th S t ree t , Edmonton, Alberta.

F. L. Peckover , C. N. R. , P. 0. Box 8100, Montreal , P. Q.

E. P e n n e r , 182 Camel ia S t ree t , Ottawa, Ontar io.

F. L. P e r r y , 4215 - 14A St ree t Northwest , Calgary , Alberta.

D. A. P e t e r s o n , 9313 - 162nd S t ree t , Edmonton, A lber ta .

Rober t P e t e r son, P. F. R. A. , P. 0. Box 908, Saskatoon, Sask.

D. H. Pol lock, 12 13 Jubi lee Avenue, Regina, Sask.

Keith Provos t , 8816 - 145th S t ree t , Edmonton. Alberta.

A . P r i o r , 214 Mer ton S t ree t , Toronto, Ontario.

R. W. P r y e r , 192 Car t ie r Avenue, Sept. I l es , P. Q.

R. M. Quigley, Geocon Ltd. , 14 Haas Road, Rexdale, Ontario.

Harold Randle, 1419 - 23rd S t ree t S. W . , Calgarv, Alberta.

J . A. Randle, 122 Yonge Crescen t , Pointe C la i re , P . Q .

Clarence Reed, 11212 - 78th Avenue, Edmonton, Alberta.

C. F. Ripley, 1930 West Broadway, Vancouver, E. C.

H. Rix , 8209 - 151st S t ree t , Edmonton, Alberta.

H. L. Roblin, 12525 - 109th Avenue, Edmonton, Alberta.

A . Sandi lands , 8910 - 117th S t ree t , Edmonton, A lber ta .

J. D. Scott, Universi ty of Water loo, Water loo, Ontar io.

B. P . Shields, 10236 - 123rd S t ree t , Edmonton, Alberta.

Alan Shor t , 1211 - 38th Avenue S . W . , Calgary, Alberta.

Gar th Simonson, 58 Ea lsom P l a c e , Winnipeg 6, Manitoba.

D. B. Smith, 14003 - 84th Avenue, Edmonton, A lber ta .

L. G. Soderman, 190 Hunt Club Dr ive, London. Ontario.

E . W. Spee r , 2321 Cumber land Avenue, Saskatoon, Sask.

R.A. Spence, 1140 West Pender S t ree t , Vancouver, B. C.

John E. Staples, 6616 - 124 S t ree t , Edmonton, Alberta.

G. Stefanick, Edmonton, Alberta.

W . G. Ster l ing, 5811 - 115thSt ree t , Edmonton, ALberta.

L. F . Swann, 5433 - 45th Avenue, Regina, Sask.

A. G . Swanson, 6204 - 94B Avenue, Edmonton, A lber ta .

J. G. Thomson, 88 Flavel le Road, Calgary, Alberta.

S. Thomson, 11407 - 55th Avenue, Edmonton, Alberta.

A. Thor ley, 1463 Bishop S t ree t , Montreal , P. Q.

R. C. Thurber , 31 18 Westdowne Road, Victor ia, E. C.

B. B. Torchinsky, 1401 Colony S t ree t , Saskatoon, Sask.

D. L. Townsend, R. R. No. 1, Kingston, Ontar io.

K. Tubbesing, 37 25 B luebonne t Road, North Vancouver, B. C.

K. F. Tupper , 120 Eglinton Avenue Eas t , Toronto, Ontar io.

W. D. Ushe r , 6412 - 131st S t ree t , Edmonton, Alberta.

H . VanderNoot, 24 Normandy Road, Ea ie D 'Ur fe , P. Q.

H. K. Walker , 8702 - 92A Avenue, Edmonton, Alberta.

B . P . Warkent in, Macdonald Col lege, Mont rea l , P. Q.

W. G. Watt, 317 Maple S t ree t , Saskatoon, Sask.

A. W ebe r , 10519 - 140th S t ree t , Edmonton, Alberta.

C. D. Westcot t , 11435 - 76th Avenue, Edmonton, Alberta.

G. C. Wheeler , 8516 - 143rd S t ree t , Edmonton. ALberta.

C. H. White, 29 Mackay Dr ive, Calgary , ALberta.

C. R. Wilkins, 9025 - 145th S t ree t , Edmonton, Alberta.

W . H. T. Wilson, 33 Centre St reet Eas t , Richmond Hil l , Ontario.

J. M. Wise, 1901 Grant Road, Regina, Sask.

P e t e r Yurkiw, 8203 - 98th Avenue, Edmonton, Alberta.