Proceedings of the Fourth Annual Canadian Soil Mechanics Conference

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NATIONAL RESEAIWHCOUNCIL OF CANADA

ASSOC!I\'l'E COMMITTEE ON SOIL AND SNOW MECHANICS

TECHNICAL MEMORANDUM NO. 19

PROCEEDINGS OF 19aO SOIL MECHAN:ECS CONfIiiRENCE

Ｎ［ｐＺｴＧ･Ｚｰｾｲ･､

and edited

by

1". L

_{. '}o

PecKover and Margaret Gerard

...

_{\. . . . . '}

Ottawa

,

TABLE 01" CONTEN'1'S Foreword Session or December 14. 1950 Page No. 1

Section 13 Use or Lignoso1 to Oombat Frost Heave

by 3. Hurtubise and RoMo Hardyo 52 Section

14

International Society or SoIl Mechanics

and Foundation Engineering by i

FoL. Peckover. Ｕｾ

Section 15 Concluding Remarks by RoF... Legget 57 ａｰｰ･ｮ､ｬｾ A .; X,ist or Those Present at the Fourth Annual

Canadian Sol1 Mechanics COnferenceo

Appendu B • Standard Terminology 1'01'

Soil

DesCl"lptlon

b7 .

N.D.

tea.

Section

e. ..

Soil Mechanics and the Winnipeg Flood

by A. Baracos.

31 .

Sectlon 9 Foundation Problems of small Buildings

b1 B.B.

Torchinsky.

40

Section

10

Interpretation ot Load Bearing Tests

by I.F. Morrison. 44

Section 11 Research Projects ot the Ontario

Department or Highways by Jo Walter. 46 Section

12

Testing Techniques !U1d Equipment by

J.M. FairbaIrn. 49

s

2 11

16

22

20

Introductory Remarks by RoF. Legget Special Foundation Problems in

Oanada by RoF. Legget Reporteor Regional Group

Activities

Investigationa. or small Buildings on Pel'/ll8!'l'Ost by 30 A. Pihlainen.

Organic Terrain by N.W. Radrorth.

Standard Terminology 1'01' Sol1 Description by N.D.

Lea.

Annual Report of the Sol1 Mechenics and Materials Departmen t or the P.F.RoA. by L.G. Chan. ' Bection 4 Section

1

Section

2

Section

3

Section 5 Section 6 Section ., Session or December 15. 1950

National Research Council in its work. Formed in 1945 to deal with an Urgent wartime problem involving soil and

snow, the Ccmmittee is now perfonning its intended task of co-ordinating Canadian research studies concerned with the physical and mechanical properties of the terrain of the Dominion. It does this through subcoumittees on Snow and

Ice, Soil Mechanics, Muskeg, and Permafrost. The Com-Il1ttee, which consists of about fif"te,en Canadiano ap-pointed as individuals and not as representatives, each for a 3-year term, has rums available to it for making research grants for work in its fields of interest.

In-quiries will be welcomed and should be addressed to: The

Secretary, Associate Comnittee on SoU and Snow Mechanics, c/o The Division of Building Research, National Research Council, ottawa, Canada.

NATiONAL RESEARCH COUNCIL

Foreword

This is the record of a Conference of most

of the active Canadian ｷｯｲｫ･ｾｳ in the field of soil

mechanics, held in the Seminar Room of the Montreal Road Laboratories of the National Research Council of Canada, in Ottawa on December 14 and 15, 1950, under the auspices of the Associate Committee on Soil

and Snow Mechanicso About 70 persons were present

from various parts of Canada to take part in general discussions relating to problems in soil mechanics

and to hear talks on allied subjects. A list of

those attending is included as Appendix A of these Proceedings.

As proposed at the start of the Conference, the first day was devoted to the presentation of

papers and reports while the second day was reserved for discussion on problems of general interest and

business matters of the Conference. The material

contained in Section 2 to Section 5 was presented on December 14 and the remainder on December 150

- 2 ｾ SESSION OF ｄｅｃＦｾｂｅｒ

14, 1950

Section 1 Introductory Remarks by Ro F o Legget

The Chairman, Mro Re Fo Legget, opened the meeting and welcomed all those present. He noted the increased

attendance over previous years, which seemed to indicate the growth of interest in the 'subject of soil mechanics in Canada.

In order to give the delegates the background of these Conferences, the Chairman outlined the functions of the Associate Committees of the National Research Councilo These Committees are set up by the Council whenever a problem of national importance arises which can best and most quickly be solved by pooling the ideas of a group of particularly . qualified people 0 These persons receive no remuneration for

their services and are chosen, not as representatives of any particular body, but rather for their spepial knowledge in the field in which they are asked to serve. The Associate Committee on Soil and Snow Mechanics was set up in

1945

to work on a specific wartime problem that of the traffica-bility of vehicles in difficult ground conditions o ｾｨｩｳ

problem in Canada has now proceeded in a satisfactorY ｾ｡ｹ and has passed entirely into the hands of the Canadian Army'o The Committee, therefore, is now occupied with civilian matters, an intention which was foreseen when the Committee was formedo for general interest, a list of the publications issued by

this Committee will be found on the inside of the back cover of this report)..

There are now four subcommittees of the Ass ocia.te Committee on Soil and Snow Mechanicso These deal with

research on soil mechanics, permafrost, snow and ice, and muskeg materials which together compose the complete sur-face terrain of Canada. It is ｵｮ､･ｾ the particular auspices of the Subcommittee on Soil Mechanics that the present Conference is heldo The Chairman said that the National Research Council is pleased to provide the facilities for such meetings which stimulate discussion and help to co-ordinate scientific work in Canadao He hoped that before long the new building for the Div is ion of Building Rese arch of the Counc il would be able to provide a meeting place for these assemblieso

Section 2

Special Foundation Problems in Canada by

R. F. ｌｾｧｧ･ｴ

Introduction

As part of the Festival of Britain, many conferences have been arranged, among them the first international con-ference dealing with building research. Canada has been asked to contribute three papers for this Conference, one of which is to deal with special foundation problems in Canada.

Mr. Legget was asked tc prepare a paper for this purpose and he asked the permission of the assembly to read this, in the hope that it might provide a general background of Canadian work in soils and foundations and stimulate discussions. Critical comments were invited.

As this paper will not be published until September, 1951, the full text cannot be included in this report. The following is a summary of the report.

Canadian engineers encounter many of the unusual foundation problems that are met with in other countries. However, the climate of Canada and its geology are suggested as being the two factors which influence foundation engineering

to such an extent as to create conditions which are peculiar to Canada to a large extent.

The paper is divided into two parts: the Geology of Canada and the Climate of Canada •.

Under the first heading, the author discusses the geological history of Canada and the resulting deposits which form the media for foundation engineering. These unusual deposits are listed by the author as follows: glacial clays, glacial silts; glacial till and muskeg. The peculiar

properties and nature of each are outlined as well as some of the difficulties they present to foundation engineering.

Under the second heading, the author stresses the extreme variations and intensities of Canada's climate. The author deals with permafrost (perenniallyfrozen ground) -the difficulties its presence presents With regard to pile driVing, the type of foundation and the effect of heat on the level of the permafrost table. Frost penetration is another problem caused by climate on foundation engineering

4

-practice in Canada and the author tells

or

Canadian practices to deal with this problem. Ice as a bearing medium is the last topic considered by the author in his paper. Although not often thought

or

as an actual roundation bearing medium, it must be considered as such and will playa big part in future research in this field. In conclusion, the author outlines future Canadian research projects in the field of roundation engineering.

Reports of R;-'}gional Group Acti vJ. ties

The Chairman described to the Conference tho Yfork of the regional groups which operate under members of the Subcommittee on Soil Mecbanicsv ReGional representatives who were present were: ｐｲｯｦｾ Spencer Bal.l or' the Maritimes, Prof. J. Hurtubise from the Montreal ｲ･ｧｩｯｮｾ ｾｾＮ ｇｾ ｃｾ McRostie from the ottawa region,p and Mr. J. AQ Knight .from the 'foronto

region. Unfortunately,p the representatives from the Prairies and Bri tish Columbia were not able to be pre,gen t. However, reports will be given on work in Manitoba by Mr. Baracos and Dean Har<;1y will report on activities in Alberta. The Chairman then called on those representatives for a report on the soil mechav:ics activitles in their respective regions.

Report from the ｾｭｲｩｴｩｭ･ｳ by Prof. Spencer Ball

Professor Ball said that, unfortunately, there were still no soil mechanics laboratories in the Maritimes. However, he was pleased to report that soil mechanics was now included as a refresher course in the Highway Department and a course in soil mechanics is to start in the fall of 1951 at the

University of New Brunswick. Professor Ball was hopeful that these two new developments would help to kindle interest in soil mechanics in the Maritimes and that next year he would

be able to report the start of a Maritimes Soil Mechanics Group. Report from the Montreal Region by Prof. J. Hurtubise

Professor Hurtubise COImnented at the outset of his review that he was very glad to be able to present a more substantial resume of activities than had been possible in

the past. At the four meetings that had been heldJ the average attendance had been about thirty persons: an indication of

the interest in 80il mechanics in this region. Professor Hurtubise then outlined the meetings that had been heldo

In February, 1950,p Mr. Robert Quintal spoke on his proposed standard graphical symbols for soils investigationo While speaking of this topic, Professor Hurtubise interrupted his review of activities to inquire regarding the status of the proposed standardization that was circulated to all

persons known to be interested in soil mechanics. Mro Peckover replied that the AoSoToMo had held a SYmposium on the

identification and classification of soilso About the same time as this ｭ･･ｴｩｮｧｾ a unified method of soil classification including soil symbols was proposed by the UoSo Corps of

6

-Engineers and the U.S. Bureau of Reclamation. As this action will have a widespread influence on such standardization in the United States, further action on Mr. Quintal's proposed classification is awaiting publication of the American work. Professor Hurtubise thanked Mr. Peckover and continued his outline of events in soil mechanics in Montreal.

At the March Meeting, Mr. Leon Fraikin of the Franki Pile Company spoke on foundation problems in Mexico and their tentative solution; and at the April meeting, one held jointly with the Montreal Branch of the Engineering Institute of

Canada, Mr. A. W. Johnson, soils engineer of the Highway

Research Board or the U.S.A., delivered a paper enti tled, "An appraisal or highway soil mechanicstl

•

In November, Mr. Norman Lea presented a paper on "The rield identirication and description or soils". This had lead to the rormation or a committee to study and prepare a memorandum on standard terminology for soil description. Mr. Lea's presentation of this paper is included in these Proceedings in Section

6.

Professor Hurtubise concluded his remarks by saying that he thought 1950 had been a successful year and that

meetings had been planned for January and February or 1951. Report rrom the Ottawa region by G. C. McRostie

Mr. McRostie commented that he was now speaking in the capacity of ex-chairman of the Ottawa Soil Mechanics Group as Mr. Peckover had recently been elected chairman. The following meetings had been held since the last Annual Soil Mechanics Conference.

In November, 1949, Dr. A. Leahey of the Dominion Department of Agriculture gave a talk on soil classification as used in agriculture. In December, an evening visit was paid to the Soil Mechanics Laboratory of the Division of Building Research. This marked the formal opening of this Laboratory and various demonstrations of soil action and testing equipment ｷ･ｾ･ giveno

In January, 1950, the group heard talks by Messrs. Peckover, Eden and Kew on the theory and application or

unconfined compression test and equipment for its performance; in February, Mr. Robert Quintal, of Montreal, gave a talk

on the adaptation of boring techniques for each individual job.

In April, the group heard a talk by Mr. Au W. Johnson of the Highway Research Board giving a complete picture of

soils research work as applied to highway design and con-struction being carried out in the United States. In July, a visit was arranged to see a demonstration of the driving of a Franki pile and Mr. Fraikin spoke to the groupo

In October Mr. W. H. Ward of the Soil Mechanics Division of the British Building Researi,;h ｓｴ｡ｴｩｯｮｾ who had been a member of a scientific expedition to Ba.ffin Island last summier, spoke on the problem of construction damage arising from swelling and shrinking clays" He :b...ad made extensive studies of this problem in Britain and elsewhere, but thought that damage from this cause was as bad in Canada as any he had ever seeno During his brief tour of the eastern part of Canada, he found at least some damage in all cities he visited.

At the Novanber meeting, Mr. Wo B. Schriever, a member of the Division of Building Research, at present attached to the Toronto Transportation Commission, outlined the construction work on the Toronto Subway and told of the soil studies being carried out in connection with this project.

In conclusion, Mr. McRostie thought that the monthly meetings of the group had been successful in stimulL ting

interest in soil mechanics in Ottawa. Next year's program has been arranged and it is hoped that even more persons will become interested in these meetingso

Report from the Toronto region by Mr. J. A. Knight

Mr. Knight reported on the activities of the Toronto Soil Mechanics Group, stating that a great deal of interest had been shown in the five meetings which had been held during the past year. The following is an outline of the meetings held in Torontoo

In October, Mr. W. H. Ward, who also spoke to the Ottawa Group, told the group about his recent studies of the Baffin Island glacier and their aspects relating to soil mechanics. The November meeting, concerning the Toronto

Subway, was conducted by Messrso MacDonald, Brown and

Schriever; as part of this meeting, the members visited the subway to view its construction0

At the January meeting, Mr. Chapman and Mr. Gorman chose as their topic geology as related to soil mechanics.

Mr. Trow of the Ontario Hydro Laboratories gave a talk on the bearing capacity of footings at the meeting in February.

8

-At the March meeting, Mr. J. Walter of the Ontario Department of Highways spoke to the group about soil

mechanics investigations in ｨｩｾＡｷ｡ｹ engineering.

Mr. Knight concluded by saying that in Toronto there are many active research organizations such as the Hydro

Electric Power Conmiss ion, the Highways Laboratory, Imperial Oil Company Ltd., and members of the group from these various lines of work helped to make the meetings informat ive and interesting.

Report from the Prairie Region

In the absence of Dean A. E. ｍ｡｣ｄｯｮ｡ｬ､ｾ Chairman of the Prairie Group, Mr. Baracos and Dean Hardy reported on activities in soil mechanics in their respective provinces. Report from Manitoba by

Mr.

Baracos

Mr. Baracos stated that the main regional interest during the past- year had been in connection with the Winnipeg flood, i.e. the effect of the flood on foundations and the use

of soil mechanics in dyke construction.

Damaging effects of the flood on foundations were not extensive but there were some unusual cases of basement floors breaking up. The opposite action to shrinkage occurred and clays and silty clays started to swell at the time of

inundation. Investigations of these occurrences are now long-term projects of the Division of Building Research of the ｎ｡ｾｩｯｮ｡ｬ Research Council.

Considering the construction of dykes, Mr. Baracos stated that wh·en the water subsided, many draw-down slides were caused along the Red River. The Dyking Board wanted design figures for dykes and analysis of these slides conveniently provided this information. The Dyking Board found that materials near the river banks were suitable for compaction, provided the moisture content was not too high.

Another ｰｾｯｪ･｣ｴ under way in Winnipeg is the

investigation of mattress foundations for inexpensive houses. These are supported on a prepared gravel bed or on virgin soil.

Regarding the status of meetings of those interested in soil mechanics in the western provinces, Mr. Baracos said that monthly meetings were not possible because of geographical factors and a "meeting" so far consisted of one or two persons getting together to discuss some problem.

of Manitoba soil testing equipment was being developed for consolidation and triaxial testing. Another project under way was the testing of properties of soils taken from the area of fOrmer Lake Agassiz.

Another group in Manitoba working on soil mechanics research is the Manitoba Good Roads Association; they have developed a soil labore, tory and are world.ng in eonjunction with the University of ｉｾｮｩｴｯ｢ｒＮ

The Chairman then asked Dean R. M. Hardy, Dean of the Faculty of Applied Science at the University of Alberta to give an outline of soil mechanics work in Alberta.

Report from Alberta by Dean ｈ｡ｲｾ

Dean Hardy reporting on compaction investigations in that province said that research on this subject was a co-operative program with funds for the investigations provided by the National Research Council, the Alberta Research Council, and industry through the Prairie Road Builders Section of the Canadian Construction Association and the Canadian Construction Association.

A co-operative program between the three Universities of the Prairie Provinces concerned with moisture migration

measurements has also been started with funds provided by the Prairie Road Builders. Another investigation is the

treatment of frost boils with lignosol. Dean Hardy mentioned that Professor Hurtubise was also working with this method of treatment. The laboratory results from the work at the University of Alberta are encouraging, and the manufacturers are, of course, interested in its possibilities. If it is successful on a practical scale it will be of great economic advantage to railroads and, to a lesser extent, to highways and runwa ys •

•

Slides in rivers in northern Alberta have also been of great interest to soil mechanics workers. These slides are associated with the construction of highway enbankments resulting from higher standards of highway construction. They originate in the material below the surface of the so-called bed-rock and are associated with highly con-solidated material. This material, in its natural state, has a comparatively high strength - from 6 to 10 tons per square foot - but when it comes into contact with water, it loses all its stabilityo

- 10

-Dean Hardy ｣ｯｾｾ･ｮｴ･､ on the fact that in ordinary highway practice, there is ｾ tendency to associate stability with flat slopes but ｡ｴｾｴ［ＮｾＮ｡ｬｬｹ flat ｳｬｯｰｾｳ may have acquired

that condition because slides have taken place and the areas may still be essentially unstable.

These slides form a very interesting investigation for soil mechanics workers as they involve deep glacial

deposits; Dean Hardy said toot this investigation would be a continuing project"

Report from the Province of British Columbia

Unfortunately no report was heard on soil mechanics activities tn this province as no one was present from

British Columbiao

Discussion

Dean Hardy had commented in his talk that he was sorry that Mr. Ward had not been able to travel as far west

as Edmonton. Realizing that many of the group present would probably not have had an opportunity to meet ｢ｾｯ Ward, the Chairman told the meeting about his part in last summer's expedition to the Baffin Icecap and his subsequent travels in Canada.

ｾｾＮ Ward is on the staff of the Soil Mechanics

Division of the British Building Research Station and, although he works mostly in soil mechanics, he 1s also a glaciologist. Because of this latter interest, Mr. Ward had been asked to

join an expedition to examine the permanent icecap in Baffin Lando On this expedition, Mr. Ward saw the phenomenon of outwash material being deposited from the icecap, and thus forming ice pressure ridges. Another item of interest, he witnessed was the formation of "bandedtt _{soils (varved}

clays)o From these observations, ＱｾＮ Ward told the chairman that the classical theory regarding the formation of varved clays did not seem to hold true. After his trip to Baffin Land, Mr. Ward stayed in Ottawa for a while, visiting

Winnipeg, Steep Rock, Toronto and Hamilton before sailing for Britaino The chairman commented that Mr. Ward, with his background in soil mechanics and glaciology would be well equipped to write about the formation of glacial soils as seen in Baffin Land and such a report would be a real con-tribution to the field of soil mechanics.

This ended the session of the first morningo Lunch was served to the delegates in the cafeteria of the Montreal Road Laboratorieso

Section 4

Investigations or Small BUildings on Permarrost by

J. A. P!hlainen

The afternoon session was under the chairmanship of Mro Fo L. Peckover. He introduced the first speaker of the afternoon, Mru J. A. Pihlainen of the Soil Mechanics

Laboratory of the Division of Building Research.

Mr.

Pihlainen is concerned with studies of foundations on

permafrost and last summer had made an extensi ve trip down the Mackenzie River in order to investigate the performance of light foundations on permafrost in the Mackenzie Valley. Mro ｐｩｨｬ｡ｩｮ･ｮＧｾ paper follows.

Introduction

More than one-half of the total area of Canada may be called "The North" 0 Largely uninhabited, but

possessing many potential resources, the full impact of its wealth has yet to be felto Foreseeing the importance of this vast part of Canada in strategic and economic con-siderations of the future, many departments of the Dominion of Canada have accelerated their work, and consequently their interest, in this regiono This short talk concerns some

of the findings of a joint expedition of the Directorate of Engineer Development of the Department of National Defence, and the Division of Building Research of the National Research Councilo Both organizations were interested in the construction techniques used for small building foundations on permanently frozen ground (permafrost)o In addition, the Division of Building Research hoped that the notes collected during the summer would be the beginning of their "Northern Domesday Book" Ｍｾ an ambitious program of particulars on the design, construction, details, and services of every building in Canada's northo

From the ｯｵｴｾ･ｴ it was realized that the northern investigations would have to be carried on for a number of years 0 The 1950 ｩｮｶ･ｳｴｩｾｴｩｯｮｳＬ therefore, were considered

exploratory and were to take the form of a small expedition through some particular area of Canada's northo The selection of the Mackenzie River Valley was prompted because it provided numerous small settlements and its water course provided the best and easiest form of transportation through the northern areao

12 -The Investigations of 1950

The four-man party was assembled in Ottawa during the middle of May. For approximately 4 weeks they were subjected to intensive briefing on all aspects of the

investigations. The party left Ottawa for Edmonton at the beginning of June and flew to Yellowknife on June 15. After a one-week stay at Yellowknife to report on this town's

utility systems, the investigators flew to Hay River to join their chartered boat. From Hay River they travelled by boat to Fort Resolution and then on July 2 they entered the

Mackenzie River. The trip down the Mackenzie River to

Aklavik took approximately a month with stops at the principal settlements of Fort Providence, Fort Simpson, Fort Wrigley, Fort Norman, Norman Wells, Fort Good Hope, Arctic Red River, Fort MacPherson and Aklavik.

Reports

Two types of reports were completed for each settlement. The first, called a "Settlement Report", con-tains a general description of the settlement, including topics such as location, topography, geology and histor

Yt

of the settlement. The second type, a "Building Report' was an lias constructed" study of every "white man" building in the settlement. Topics covered in this report were location, construction history, sketch plans, photographs, soil and permafrost conditions, foundations, floor, ceiling, wall and roof sections, and outlines and notes of failures. Over 250 buildings in 12 settlements were reported on in this manner0 In addition, approximately 800 terrain and building

photographs were taken on the 1400 mile trip.

Comments On The Different Tyhes of Permafrost Foundations In The Mackenzie iver District

Except for Norman Wells, the buildings in the

ｉｾ｣ｫ･ｮｺｩ･ River settlements arrange themselves into functional groups, such as Hudson's Bay Company buildings, Royal Canadian Corps of Signals buildings, Mission building& RoC.M.P. buildings, and buildings for personnel of various government departments.

In addition, there are the usual native shacks and the familiar small native summer tent cities.

Mudsills.- The predominant type of foundation for the district is the timber mudsill. However, the frequency with which it appears should not be taken as an endorsement of its effectiveness. The main advantage of the mudsill

is that it is a cheap and easy type of foundation to con-struct. Resting on the ground surface, it is very

susceptible to frost heaving as well as settlement due to the lowering of the permafrost table.

Piles· - It is thought that piles form, for the present time, the most important type of permafrost foundation. Steel pipe piles are the most prevalent type in Nonnan ｗ･ｬｬｾ where they are obtained from scrap at practically no cost. Native timber piles are used for the most part at the other

settlements.

Concrete Wall ｆｯｯｴｩｮｾｳＮＭ It ｷ｡ｾ found the. t more than one-half of the buildIngs wIt full concrete basements and concrete wall footings have shown apparent failures. Because of this, there is much reason to doubt the need for basements in

Arctic dwellings. If this need is justified then work on the modification of present practice is called for.

Other Foundation Types.- The other types of foundations encountered, timber posts, short concrete piers, timber pads and concrete pads, formed approximately 25 per cent of the foundations investigated. With the possible

exception of short concrete piers, they were generally found to be unsuitable permafrost foundations.

Future Work

Sufficient information was ｾｴｨ･ｲ･､ in the 1950 Mackenzie River investigations to indicate where research is needed. However, the amount of work to be done is of such magnitude that it will require years before it can be accomplished. Present policy is to plan field work on topics where the lack of information is of immediate concern. A program of field studies on piles is planned to supplement informa'tion gathered by R. A. Hemstock at Norman Wells. The 1950 Mackenzie Valley investigations also showed a decided lack of informa tion on gravel mats. The urgency with which this type of data is required is as great, if not greater, as that of design data for piles. However, the scope and instrumentation for gravel mat studies are thought to be such that more time is required to plan field studies.

14

-Discussion

Mro Mathys asked the speaker if the depth to which a pile should be driven could be ascertained.

Mr.

Pihlainen replied that first, a measurement should be made of the

thickness of the active layer and twice this amolmt was the depth to which the pile should be driven into the permafrost.

Mr. Pihlainen cOlD...'1lented that it wa,s important to drive tne pile far enough into the ｰ･ｲｭ｡ｦｲｯｳｴｾ as sometimes the perma-frost table is lowered slightly by disturbance of the active

layer during pile-driving operations.

Dean Hardy commented on the effect of different

heat flows along steel and wooden piles as found by measurements at Norman Wells. Temperature readings were taken during the first summer of observations and it was found that the perma-frost level was lowered 4 inches by the steel piles and I inch by wooden piles. Dean Hardy suggested that the only way in which reliable data could be obtained from pile studies would be by keeping a diary with a complete construction history and notes of any exterior influences which might affect the function of the piles.

Mr.

Gilbert mentioned the fact that at Hay River many houses were constructed from salvaged materials and

were placed on piles. After a year, the piles under one such house had settled around the corners and one side, from 1

inch to

I 1/2

inches.

Mr.

Gilbert said that no heaving was evidenced and wondered if the steam used in pile placing operations could have caused thaWing of the permafrost and resultant settlement of the piles.

Mr.

Philainen said that in comparison to Yellow-knife» the amount of steam used at Hay River seemed to be excessive. However, there are so many factors which may account for failures of buildings on permafrost» that a definite answer could not be given unless more details were known.

Mr.

Mathys said that he considered settlement strange in these cases. He mentioned that in July at Churchill, it took 2 hours for the piles to become frozen into place. After 2 hours, it was impossible to move the piles ,but after 2 years the same piles moved and caused damage to the building.

A comment was then made that settling of piles only occurred when the permafrost table was lowered below the bottom of the pile.

No conclusions were reached but it was generally agreed that the subject of permafrost foundations was one which was worthy of investigation.

While preparations were being made for

Dr. Radforth's talk, Professor Morrison contributed some comments on how the permafrost deposit had reached its present position at Yellowknife. He mentioned that at some time in the past, the level of Great Slave Lake was very much higher than it is now. There is a well defined beach at a high elevation,. and evidence of another lower beach, still above the present level of the lake. It is apparent that the level of the lake fell very quickly and deposits were laid in deep water, thus accounting for the extremely fine nature of the sediments. When the lake dropped for the second time, these fine deposits became exposed and permanently

frozen, before any great consolidation took place under their own weight. In order to find out the time interval from the drop from the second beach to the present level, it would be interesting to procure an undisturbed sample of frozen soil and conduct a consolidation test to find the degree of consolidation which took place before freezing occurred.

- 16

ｾ Section

5

Organic Terrain by N. W. Radforth Introduction

"Mr. Peckover introduced Dro ｎｾ Wo ｒ｡､ｦｯｲｴｨｾ Head of the Department of Botany, McMaster University, who had been asked to tell the meeting of his recent ｩｮｶ･ｳｴｩｾｴｩｯｮｳ on organic terrain ..

Dr. Radforth began his talk by saying that the importance of the subject of "muskeg" bad been heightened by many discus sions and quest.ions.. The name "muskegt! is an empirical term, and this in itself introduces a complex

problem of frustrating proportions. Reference to the medium rests far too heavily on personal interpretation, and is affected by misunderstanding, misuse of terms, and lack of knowledge of the fundamental characteristics encountered when the medium is even superficially inspected. ｾｳ there is as yet no system of classification of "mUSkeg" -- or organic terrain, as it may more appropriately be called no one can say What it really is.. Even organic terrain differs and therefore, before the designation carries a desirable degree of usefulness, appropriate and accurate qualifications must be prescribed •.

There are many interests associated with this subject. To mention only a few: botanists and agriculturalists are

aware that the medium is a biologically influential foundation for a large part of Canada's vegetal coverage, and would like to have some measure of its quality, variation and worth as a controlling envl,ronmental agent supporting growth and distribution of plant populations» foresters are interested in "mUskeg" as a medium of coverage in relation to drainage, transport problems, and as a potential factor controlling tree type, density and distribution; industrialists are interested in its usefulness; and engineers encounter it in a variety of fundamental problems, eog. in secondary road

｣ｯｮｳｴｲｵ｣ｴｩｯｮｾ und in all manner of circumstances where it controls trafficability or provides special problems in

drainage and excavation. Owing to its inherent elusive proper-ties, quite apart from its variation in depth growth,

distribution and insulating potential for permanent or active frost, it represent;g a unique category ofsoilo In our country its significance is correspondingly unique

From whatever aspect organic terrain is considered, the troublesome factors are always the same. These point inevitably to a need for an intelligent reference system

to the medium. Hence, from the beginning of the investigations the question of classification has had priority. Here, as

with other soils, the ultimate units providing the structure of the medium were important elements to designate and describeo They might be even more significant as units ｴｨｾＡ the particles in mineral soils. However, the properties of gross specimens of "muskeglt _{would be the most useful attributes on which to}

build a system of classification. Hence the particulate

re-lationships, though fundamental, must provide a subsidiary system of classification and point the way in the evolving of a main, more inclusive, system. Finally, it was already evident that such things as environmental factors which ･ｮ｣ｯｵｲ｡ｾ･､ local pp-ysiographical phenomena to e;rise in the "muskeg' must also be incorporated into the system of classification.

Particle size, properties of bulk soil, and environmental influence were also starting points in the classification of mineral soils; hence this compound basis as applied to organic soils was not altogether new.

Initial research is passing througn three phases: (1) general exploration for phenomena responsible for

variation in organic terrain. This is accompanied by a search for and a segregation of qualitative data broadly applicable to organic terrain; t2) specific and methodical recording

of quantitative data for certain selected examples of terrain;

(3) basic formulation for a system of class·ification. As

information from these is discovered or derived, it i's appl ied to fifteen special items listed as follows:

10 Utilization of micro and macro fossils in organic terrain characterization.

20 The classification of ｰ｡ｬ｡･ｯｰｨｹｳｩｯｧｾ｡ｰｨｩ｣｡ｬ phenomena relative to variation in consistency of organic terrain.

30

The relation between fossil components and physiographic conditions in evaluating organic terrain for trafficability.

4.

Organic layer structure variation in relation to seasonal change in the ice component of the terrain.

50

Changes in the constitution of the organic layer in terms of a vertical axis in six experimental areas.

18

-6. Permafrost surface contour apparent in relation to constitution of the organic over-burden.

7. Influence of organic over-burden on physical

characteristics of the active and persistent ice. 8. The degree to which ice is permanently incorporated

into the organic layer.

9. Seasonal change in bearing value of the organic terrain as tabulated according to the conditions controlling the various classes of peat.

100 The effect of continued traffic on the constitution and quality of organic terrain.

11. The relationship of the constitution of organic over-burden to polygon forma tion.

12. Utilization of physical values for typing organic terrain that have been classified according to a palaeobotanical system.

13. Terrain unevenness in relation to composition of the sub-surface organic medium.

14. Comparisons of peaty material collected from widely separated zones across the north.

150 Structure variation in surface vegetation relative to sub-surface conditions.

As part of his talk Dr. Radforth showed Kodachrome slides taken mainly in the area around Churchill, but some from the Orkney Islands and northern Sweden were inclUded. The importance of the photographic medium in this work was emphasized. Dr. Radforth said that he felt certain that the relationship between properties of surface and sub-surface conditions could be elucidated. In so doing, the importance of different types of plant structure was

manifest. And it is not necessary to make reference to botanical names in the ultimate system for classification. It is, however, important to recognize certain physical units of structure. In this way the classification system

The photographs demonstrated the variation in structure and depth of organic terrain which accumulate s along wi th the active layer of permafrost. The s igp ificance of seasonal colour changes in the classification system

was emphasized.

Dr.

Radforth spoke also of the utilization of aerial photographs. It is expected that correlation of the terrain colour parts thus obtained with the ground survey data will make it possible to determine what lies beneath any given surface type.

Modes of trafficability can also be classified with regard to the appropriate features of organic terrain.

The creation of systems of classification of terrain properties and phenomena is quite complex, and the ground investigations must be recognized as comprising not merely a single problem, but a wide new field of study.

The meeting then adjourned to the Soil Mechapics Laboratory to see many samples of "muskeglt

, coloured slides,

and analysis charts which

Dr.

Radforth had been good enough to bring. All these, coupled with

Dr.

Radforth's talk, gave the delegates an insight into the problems connected with organic terrain which have arisen in the present in-vestigation.

20

-SESSION OF DECEMBER 15, 1950 Section 6

Standard Terminology for Soil Description by

No Do Lea

The Chairman for the morning's session was Dean Hardy0 After outlining the proposed agenda, he introduced

the first speaker, Mro Norman Lea of the Foundation Company of Canada Limited, Montreal, who told the group of his

proposed "Standard Terminology for Soil Description". Mr. Lea mentioned that at a Quebec and Montreal soil mechanics group meeting held last November, two samples of soil were distributed and those present were asked to write what they thought was a complete and adequate

description of each sample which could be used as an outline for a laboratory testing programo The results,

Mr.

Lea said, were what one would expect -- everyone had a different idea about the samples and about the way in which they should

be described. Much of soil terminology tends to be flavoured with purely local terms, and often these terms lead to con-fusion with the same terms referring to different soils elsewhere.

With this background, Mr. Lea told the delegates about the main points raised in his paper. A copy of this paper ent-i tIed" Standard Terminology for Soil Description" is included in this report as Appendix B and will not be described here.

However,

Mr.

Lea commented on several items in his paper which were of interest. Item 3 in his field

description of soil (soil colour) can be used to correlate boring projects from site to site and so is an important

considerationo Items 9,10, and 11 (cohesiveness near the plastic limit, dry strength, response to the shaking test) are important but can not be related to any laboratory

tests as they are co-ordinates of plasticity.

In Section VI of his paper the speaker said that geological terms generally refer to a group of soils Which are distinguishable because of some peculiar group of

In conclusion, Mr. Lea remarked that he was pleased to be able to give this paper to the delegates. It was only a suggestion for a standardized system -- to be accepted or not -- but the main thing, in his mind, was that some system should be agreed upon and used by everyone to obliterate the confusion that results at the present time from misconceptions of different soil terms.

Discussion

In reply to Mr. Trow's question as to how his paper fitted in with the work of Professor Burmister, ＱｾＮ Lea said that he believed they were someWhat similar with the same basic idea.

Mr. Torchinsky, after commending

Mr.

Lea on his work, said that he understood that the U.S. Bureau of

Reclamation was working with the U.S. Public Roads Administration on a classification similar to that of Casagrande, thus tieing in with Mr. Lea's suggestions. He thought that if these well known American organizations were working together on a

classification, Canadian workers in soil mechanics could well accept their suggestions.

Mr.

Lea was not sure that they were co-operating on this project. He understood rather that they were working on the classification of soils rather than a descriptive system.

Mr. Peckover said that, as Mr. Legget was a member of the Subcommittee on Soils for Engineering Ｍｾｵｲｰｯｳ･ｳ of the A.SoToMo perhaps it would be wise if Mr. Lea's suggestions could be submitted through Mro Legget to this body.

Dr.

Radforth congratulated

Mr.

Lea on his fine work saying that he considered the approach to the problem

excellent. He said that even though the treatment is based on description, we are nevertheless dealing with classification but in more desirable terms.

Section 7

Annual Report of the So:U Mechanies and Materials Departmenr-0r the P.F.R.A.

by L. Go Chan

The Chairman called upon Mr. Chan to outline the year's activities in Soil Mechanics of the PoF.RoAo

General

The Soil Mechanics and Materials Department, in

｣ｯｾｯｰ･ｲ｡ｴｩｯｮ with other branches of P"P.R.A., is responsible for the investigation, design, control during construction and test installations9 for foundations, and all earth

structures required for P.F.R:A. projects. This Department is divided into field exploration .. laboratory testing,

design studies and reportsv field inspection and installation

of test apparatus. The headquarters of the Soil Mechanics and Materials Sectior. is In Saskatoon where the parent

laboratory and the administrative office are located. In addition, three field laboratories have been established on

important projects. The Soil Mechanics and Materials Section has been expanding since its beginning in 1940. During the past year9 further expansion has occurred particularly in

the fields of concrete and materials. The section now employs a staff of about 110, of which fourteen are graduate engineers, about half of whom have formal training in soil mechanics or concrete. During the past year the expenditures in connection with the entire section were approximately $40090000

Field Exploration

This section is responsible for all drilling, sam-pling and miscellaneouS\';, field tests required in connection

with the investigation

or

proposed dams, canals and foundations for structures0 The test holes drilled by this division are

logged in the field and representative samples are sent to the Saskatoon laboratory or field laboratories for further testing. Most of the drilling carried out by this section is with equipment owned and operated by P.F.R.Ao but during the busy periods several contractors are hiredo At the present time the P.F.RoA. operates two rotary drills, one relatively light unit capable of drilling to a depth of

about 19000 feet and another somewhat heavier unit capable of going to a depth of 2500 feet.

In general, 2 1/2-inch push samples or 2-inch continuous cores are recovered with these maChines. However, a 6-inch double tube core barrel is also available for special

samples. A cable tool machine is also in use and either 2 1/2-inch or 4-inch undisturbed samples and bailer samples are obtained with this machine. One earth auger capable of drilling 12-inch or 36-inch holes to a depth of 20 feet

is now in use and another unit capable of drilling 16=inch holes to a depth of 16 feet has been ordered. These units have been found very useful for exploring canal routes and borrow pits for the larger dams'.

A very large portion of the work is now being

done by hand-operated washbore outfits. At the present time equipment is available for 4 such outfits and surprising as it may seem these outfits generally drill a greater footage in a year than an equal number of power-driven machines. In general, 2-inch undisturbed samples are recovered with the washbore equipment. This type of equipment has proved the most valuable for relatively small damsites that are inaccessible to heavier equipment without a certain amount of preparation.

During the past year a horizontal drill or hydrauger has been added to the equipment of the exploration section. While this unit is operated by the Exploration Section it was intended to drill holes for drainage rather than to

secure samples. Up to the present time some 6 or 7 horizontal holes have been installed to reduce water pressure in slide areas. It is felt that this is a very valuable piece of equipment for stability work. It is described in detail on Page 256-260 Volume 3 of the Second International Con-ference on Soil Mechanics and Foundation Engineering. Note Year ending Dee/50 - 55,000-60,000 ft. drilled with ---- P.F.R.A. EqUipment.

10,000 ft. drilled by Contract Equipment. Laboratory

No great ｣ｨｾｮｧ･ has been made in the Soil Mechanics Labora tory during the past year and the equipment ha.s been

covered in previous reports. In general most of the laboratory wmk has involved classification and routine testing. While the

number of consolidation tests is qUite great the number of shear tests has been very limited and required only for

special projects. In general, our Section relies to a large extent on classification tests and semi-empirical methods

24

-rather tr..an the more detailed testing. The reason for this is to build up a fund or inrormation about certain type materials and once the type has been identified, sufficient informa tion is on file to gi va a rairly good picture of its properties.

During the past year further research has been done in cormection with the Bearpaw shale which is a high swelling clay shale with very high Atterberg limits. A research program in which the various methods of conducting the liquid and plastic limit tests were studied, has been carried out.

Design Studies and Reports

During the past year further improvements have been made in methods of tabulating soil test results. For the smaller projects water contents and a few limits are shown adjacent to the drill log. However, for the larger projects the data are plotted adjacent to the drill log. The amount or office space required for these studies has been greatly increased during the past year to cope with the expanding program.

Fill Inspection and ｉｾｳｴ｡ｬｬ｡ｴｩｯｮ of Test Apparatus Construction

Construction forces have carried out routine

control tests such as water content and density or the fill being placed and also compaction tests and other routine tests in the field laboratories. In addition, a number of piezometers and settlement devices have been installed. st. Mary ｐｲｯｾ

The St. Mary

Dam,

which is the key structure on the St. Mary-Milk River Project, is now nearing completion. The earth fill was completed this past fall and some work remains to be done, on the appurtenant works. This Dam

consists largely of glacial clay from adjacent borrow pits. In general the material was slightly drier than the optimum for compaction and it was therefore irrigated in the borrow pit previous to construction. Satisfactory compaction was obtained by 12 passes of Bureau of Reclamation type rollers exerting unit pressures of 400 - 500 p.s.io Approximately 100 per cent of standard Proctor density was obtained. In general the most troublesome thing in connection with the fill operation had to do with the drying out of the fill

surface ever week-ends and during hot, dry periodso On

these occasions it was necessary to add water by sprinklingo During construction extensive pore pressure and settlement apparatus was installed in the dam.. This equipment was the same as that being installed by the Bureau of Reclamation in their ･｡ｲｴｨｾｦｩｬｬ dams .. To date, .no excessive pore

pressures have been recorded but the settlement at the point of maximum fill has now reached

5

to 6 feet ..

The Pothole ｄ｡ｭｾ an earth-fill ｡ｰｰｲｯｸｾｭ｡ｴ･ｬｹ 130

feet in height, was completed several years ago and observations of the pore pressure and settlement have been carrie d out in this structure 0

In general the Bureau of has proved entirely satisfactoryo was used from the terminal well to Saran tUbing is now being usedo

ｒｾ｣ｬ｡ｭ｡ｴｩｯｮ type apparatus Initially copper tubing the piezometer tips but During the past year extensive canal construction has been carried out on the Sto Mary project and the Soil Mechanics Section has determined the soil profile in advance and the material is logged after construction is completed .. In some sections porous materials (sands and gravels) have been encountered and some lining work is being carried out ..

Up to this point the lining material has been lean and medium plastic clays from adjacent areas, the main problem being the fact that these borrow pits are far below the optimum for compaction ..

A number of fairly important earth dams are

associated with the canal system and these have been inves-tigated and designs suggested ..

A 200-foot high earth dam on the Waterton River is now being studied.. It is presenting ｾ very interesting design problem in that the foundation consists of 40 to 70 feet of pervious sand and gravel and it is felt that sheet piling could not be driven through this material .. A blanket is tentatively proposed to reduce seepage .. Bow River Project

The PoFoRoAo has recently purchased this project from the Canada Land and Irrigation Co .. , an English company that began the development of this area early in ｴｨｾ century but has recently encountered financial difficulties .. The PoF ..RoA o propose to rebuild portions of the project and increase the irrigable area.. While there are numerous soil mechanics problems on this project, the principal one involves a side hill canal through approximately b _{miles of unstable} shale and overburden materialo Extensive sliding is now

occurring in this material and as it is a stiff fissured claY9 future stability is very questionableo At the present

26

-time as an alternative to the canal a 135-foot dam which would flood out the 6 miles of canal is under'consideration. ExtenRive studies have been carried out along the route of the canal and at the side of the dam.

South Saskatchewan Project

From the standpoint of soil mechanics, this is our largest and most extensive project. For a number of years an investigation has been carried out of the main dam on the South Saskatchewan River. This dam will be 210 feet in height and is founded on about 90 feet of fine to medium sand which overlies a soft shale bed-rock. While the pervious sand presents a problem from the soil mechanics point of view, it

is a straightforward problem as compared with the instability of the Bearpaw shale which occurs on the banks, and through which the appurtenant structures must be placed. This shale has proved to be an extremely unstable material and extensive

studies are being carried out to determine what slope might be stable in this material. Much work is being done on similar materials on the Missouri River Project of the U.S. Engineer Corps and the P.F.R.A. is co-operating with them in

studies on this material. To date, about 50,000 feet of test holes have been put down at the damsite.

In addition to the main dam on the South Saskatchewan River another dam in the Qu'Appelle Valley over 100 feet in height will be required to prevent waters of the reservoir from escaping through this depression. Five sites have been investigated and a tentative site has been chosen. Preliminary information only has been obtained on the Qu'Appelle Valley site whereas detailed information has been obtained on the South Saskatchewan damsite. The design studies on the latter site are at a very advanced stage.

Projects in British Columbia

The first major dam of the PoFoR.A. in British Columbia has recently been completedo This is an earth-fill dam about 70 feet high near Kelowna and is interesting in that it was founded on a very ｰ･ｲｶｬｾｵｳ foundation. The depth of pervious material in the foundation was a maximum of 70 feet and$ as it appeared impractical to cut this off, a partial cutoff about 30 feet deep combined with an upstream blanket was used. In addition$ drainage wells were also provided.

A number of other damsites are now under in-vestigation. Conditions in B.C. are vastly different from

the prairies where glacial clay is a predominant material; in BoC., silts, sands and gravels appear to be predominant.

Special Studies

Canal ｌｩｮｩｮｧｯｾ As the prime purpose of the work of PoF.R.A. is irrigation, it is only natural that the lining of canals to reduce water losses is extremely important. In the earlier years of P.F.R.A. very little lining was carried out but at the present time extensive experimental work is being done and a number of sections of canal have been lined. Two types of lining that are considered suitable are a compacted clay lining with a cover of sand and gravel and an asphalt membrane lining consisting of catalytically blown asphalt covered with about a foot of soil. Several sections have been lined using

compacted material and for the most part this method seems

entirely satisfactory as a great improvement in water tightness has been attained. It was feared that this type of lining

would deteriorate rather rapidly with wetting and drying ｾ and freezing and thawing. Where cover has been provided9 it would appear that the lining is not deteriorating very rapidly.

Only one section has been lined using the asphalt material and to date it appears entirely satisfactory. Further work

is proposed using both a compacted clay lining and asphalt. In addition, exper:imental work involving a soil-bentonite mixture and gunite have been carried out although the

effectiveness of these types have not yet been determined. In addition to studying canal lining materials, the organization is also extremely interested in studying

economical means of lining leaky dugouts. This phase of the work is just starting but several dugouts have been lined ·by mixing one pound of bentonite per square yard into the top 3 inches to 6 inches of soil. However, the effectiveness of this method has not yet been determined. In addition, one dugout has been lined with catalytically blown asphalt on an experimental basis.

Seepage Tests through Sheet Piling Sheet Pilin

r

Tests.- The proposed dam on the South Saskatchewan

River, at S te 10 between Outlook and Elbow, saskatchewan, will be located on a sand foundation in the river section. This sandy zone, some 2,000 feet in width, varies in depth

from 10 feet at the river banks to about 100 feet at the centre. In order to reduce the percolation through this

sandy zone under the dam, four proposals are being considered: (1) an impervious cutoff core placed under the dam,

28

-(3) an impervious blanket placed over the sand on the upstream side of the dam,

(4) a combination of two or more of the above.

To ascertain the effects of a sheet pile wall, tests were conducted at the University of saskatchewan. A steel tank was constructed, which could accommodate

various sections of sheet piling. Attachments to the tank enabled the measurement of flow of water through the sheet pile interlocks, and the corresponding drop in pressure for various rates of flow across these interlocks. Typical river sand from Site 10 was used in all the tests, and the test section was made as representative as possible of the conditions which would exist under the proposed dam. Three arch-web type of sections were tested, one a Canadian section, one a British section, and the third an American section.

By using these test results, one can estimate the effects of a sheet pile wall under the proposed dam; for example, the reduction in flow and the reduction in uplift pressure. In this manner, an estimate can be obtained of the merits of sheet piling versus the merits of each of the aforementioned proposals, and the comparative cost of each can be calculated.

A test tunnel has been driven into the valley wall at the site of the proposed dam on the South Saskatchewan River for the primary purpose of obtaining estimates of the magnitude of both lateral and vertical pressures which the

soft shale bed-rock will exert on the permanent lining of tunnels or conduits.

The test tunnel penetrates the soft shale bed-rock a distance of about 370 feet. The cross-section is roughly rectangular, 6 1/2 feet wide by 7 1/2 feet high. Earth pressure measurements are being taken at the innermost end in a 20 foot length of the tunnel, referred to as the

"pressure test section". The pressure test section is lined continuously with reinforced concrete slabs on the sides, floor and roof of the tunnel. The slabs are held in place by columns through which loads may be applied with jacks and the pressure measured by strain readings. Initially, pressures equal to the overburden pressure were applied horizontally to the· wall slabs and vertically to the floor and roof slabs. Since that application, measurements

have been taken to observe changes in the pressures in the slabs. It was predicted that the pressures would initially drop someWhat, after which in possibly an interval of a year

the pressures would increase and the horizontal pressure might eventually exceed the overburden pressure. To date,

the pressLwes have been dropping off ｧｲ｡､ｵ｡ｬｬｹｾ with an average reduction of 8 per cent for the horizontal ｰｲ･ｳｳｵｲｾ

and 18 per cent for the vertical pressures.

The bed-rock formation is the Bearpaw shale which is a ｳｯｦｴｾ very highly plastic sh&le with the appearance and behaviour of a ｬ｡ｫ･ｾ｢･､ clay. The average liquid lind t of the material along the axis of the tunnel is about 110

and the plastic limit is about 22. The material has exhibited spectacular behaviour in the tunnel0 At some sections the

shale has squeezed in about 10 inches per wall along the sides and at these locations has ｣ｲｵｾｨ･､ a part of the very heavy timber support system.

The shale is a very difficult foundation material, primarily because of its swelling or rebound characteristics on removal of load. For this reason, excavations for tunnels,

｣ｯｮ､ｵｩｴｳｾ spillway channels and powerhouses will pose the major problems of the project.

Pressure Test Section in Geological Drift.- Report will be forthcoming and may be sent to anyone interested.

Work for Outside Organizations

During the past year the 80il Mechanics and Materials Section of P.F.R.Ao has carried out ｾｯｭ･ outside work for

other government agencies particularly where the work involves

､ｹｫ･ｳｾ dams and other structures. In this ｣ｯｮｮ･｣ｴｩｯｮｾ work

has been done for the cities' of Winnipeg, Regina and Saskatoon and the Provinces of Uanitobaj Saskatchewan and Alberta.

Co-operative projects have also been undertaken with the University of Saskatchewan.

Discussion

After

Mr.

Chan's talkj Ｑｾｯ Gilbert asked if the

report on seepage thrOUgh the sheet piling would be available and ｲｾＮ Chan replied that it would be.

Mr. Lea asked if the timbers in the test tunnel were broken by shale and if they had been placed tight against the shale. In reply to this Mr. Torchinsky said

that there was initially an interval of about 2 inches between the timbers and shoring. Mr. Mathys said that he thought at the time of his visit that timbers were tight at the corners with space for movement between. Mr. Lea then said that it was recommended, when working in shale, to

30

-leave a @ap of 2 to 6 inches between the shoring and the rock. Mr. Mathys commented that, if this practice were followed, the rock would have to be scaled.

Mr. Torchinsky remarked the. t the P.F.R.A. had completed a concrete testlng laboratory which houses a

ｾ｡ｰｩ､ freezing and thawing device with which alkali effects on concrete would be investigated.

Soil Mechanics and the Winnipeg Flood by

Ao Baracos

The Chairman called upon Mr .. Baracos to tell the group about the work done in connection with the Winnipe g flood with regard to soil mechanics 0

Mr0 Baracos stated that during

1950

the following

four groups were actively working on soil mechanics in

Winnipeg: the National Research ｃｯｵｮ｣ｩｬｾ the Greater Winnipeg Dyking ＳＰ｡ｲ､ｾ the Mani toba Good Roads Depar tme nt and the

Univers.ity of Manitoba.. He then briefly outlined some of the activit ies of these group s ..

Nat ional Research Council

study of ｄ｡ｭ｡ｾｯ House Foundations as a Result of the

1950

ｆｬｯｯ､ｯｾ The Division of Building Research of the National

Research Council was interested in the effects of inundation on house foundations resulting from the

1950

flood in Manitoba .. One of these effects was the differential movements which

often ｯ｣｣ｾｲｲ･､ in house foundations and were in the order of 2 to 3 inqheso Swelling of certain clays, Which support many of the lighter ｢ｵｩｬ､ｩｮｧｾ in ｗｩｮｮｩｰ･ｧｾ appeared to be the cause of the movement .. These clays are ｾ｡｣ｵｳｴｲｩｮ･

deposits of the glacial age Lake Agassiz which covered a large part of Mani tobao

From test holes in the vicinity of where swelling

ｯ｣｣ｵｲｲ･､ｾ it was found that a ｧｲ･ｾ to Ｆｲ･ｹｾｹ･ｬｬｯｷ clay, highly stratified in horizontal layers ranging in thickness from 1/16" to 1 inch and moreg and very stiff in the

undisturbed conditiong appeared to be the main source of

swelling.. It ranges in depth from near the surface to 20

feet and more9 often having many horizontal layers of silt. A characteristic of the clay is that it possesses pockets

of white crystalline materialo A study has been initiated to determine whether these crystals can be associated with the swelling of the clays and to determine what they areo

The "symptoms" of swelling were often unusual.. In one case the basement floor of a house had lifted

3

inches relative to the foundation wallo In moving9 the floor had lifted a brick chimney which then protruded

3

inches higher

32

-above the roof of the house. The chimney flashings were

that much above the roof shingles. Although the chimney was on a separate footing as was shown by excavation, there appeared to be sufficient bond between chimney and floor

to lift both ..

Swelling appeared to be greater under lightly loaded areas such as basement floors than under foundat ion walls and post footings. Thus basement floors which rested on the foundation footings were often lifted off the footings. Since there was no material between the bottom of the slab and the top of the footing, a break was not uncommon where the slab remained cantilevered; and a crack appeared all around the floor space.

Proof that such heaving was due to the swelling of the soil was established in one apartment house in Which the foundation wall footings had been underpinned with piles 38 feet to hardpan. In the basement apa.rtments; the floor slabs which were resting on the clay, had heaved and were broken. On excavating, it was found that the wall footings were still resting on the piles and therefore damage could only be the result of soil swelling under the floors.

Tests have also been run to determine the swelling properties of the clays. It has been found that large changes in volume are associated with changes in ｭｯｩｳｴｵｲｾ content, Since very little information was available on soil moisture contents before the flood, the field changes in moisture content could not be determined. Test holes have been bored since the flood and will continue to be bored to determine these changes. From a limited number of examples, it is interesting to note that most of the swelling occurred in buildings where an excavation had been made for a basemento

Soil swelling was not general throughout the

flooded areas. Foundation material in many parts of Winnipeg is a river-deposited granular material which does not exhibit appreciable changes in volume with changes in moisture content. Swelling also occurred in certain non-flooded areas. Heavy rains and melting snows were contributing factors in these cases. Weeping tiles used around foundation walls and under basement floors probably provided a path for the water to reach the soilo Since many sewers had been plugged by house owners and tenants to prevent sewage backing into the basement, the water could not drain awayo

Otlwr foundation failures were attributed to poor building practice. Building foundation walls of concrete blocks and lime mortar, which are no longer permitted in Winnipeg, were found to be dmnaged by the effects of lateral

earth pressures. Other examples of poor building practice were basement1ess houses resting on surface foundations with a dug-out to house the furnace. ｾ･ walls of the ､ｬｾＭｯｵｴ

which were often shored with timbers that had rotted, stood up a s long as the so il was dry, but when it became wet., the sides of the excavation caved in towards the dug-out.

Removal of support that resulted, caused adjacent surface footings· to settle.

Reinforced concrete foundations generally suffered very little damage.

The Winnipeg Building Code requires that basement posts supporting floor beams in a house have footings which are independent of the floor. These consist of a cap under

the post; the cap tapers out to a pad which rests In the soil beneath. The post is then not affected by movement of the basement floor. If swelling occurs under the floor, it can move upwards without lifting the posts. The same

construction has been found to be satisfactory when shrinkage has occurred. The clays that swelled due to the flood appear to be the same ones that caused large settlements durh!g the dry years. Some cases were noted where damage had occurred because a bond had formed between basement floor and post footing. Partition walls resting on the basement floor were found in some cases to have lifted the centre of the house and caused similar damage.

Another common occurrence due to the flood was the erosion of the backfill around houses. This was caused by the velocity at which the water flowed between some houses and resulted in the scouring of loosely packed backfill.

Damage as a result of a large hydrostatic head was observed in a large industrial building. Its basement floor was 14 feet below the high water mark and every effort was made to keep the basement dry. The result was that

a section of the basement wall backfill flowed illlder the wall footings and pushed up the basement floor about 6 feet. From this experience, it may be recommended that basements be allowed to flood rather than to risk the effect of high hydrostatic pressures. Very little evidence of similar damage to houses was observed.