The Canadian Geotechnical SocietyThe Canadian Geotechnical SocietyLa Société Canadienne de GéotechniqueLa Société Canadienne de Géotechnique

CROSS CANADA LECTURE CROSS CANADA LECTURE TOURTOUR

SPRING 2009SPRING 2009Characteristics of organic soils Characteristics of organic soils

andandconstruction on organic terrainconstruction on organic terrain

Arvid Landva, Dr.Ing.*, PhD.**, PEng, Arvid Landva, Dr.Ing.*, PhD.**, PEng, FEICFEIC

**Norwegian Institute of TechnologyNorwegian Institute of Technology**Université Laval**Université Laval

T e r r A t l a n t i c

E n g i n e e r i n g L i m it e d

Sponsors For Cross Canada Lecture Tour, Spring 2009

The Canadian Foundation for GeotechniqueLa Fondation canadienne de géotechnique

The Canadian Geotechnical SocietyLa Société canadienne de géotechnique

Sponsors For Cross Canada Lecture Tour, Spring 2009

Organization:

Funding:

TerrAtlanticEngineering Limited

• Geotechnical Engineering • Hydrogeology• Environmental Engineering

515 Beaverbrook CourtFredericton, New BrunswickCanada, E3B 1X6

www.terratlantic.nb.caTel: (506) 460-8660Fax: (506) 460-8679

The following presentation is available on our website.

FIGURE 4.14 AND TABLE 4.2 FROM MUSKEG FIGURE 4.14 AND TABLE 4.2 FROM MUSKEG ENGINEERING HANDBOOK 1969 AND FIGURE ENGINEERING HANDBOOK 1969 AND FIGURE

9(b) FROM Hobbs 19869(b) FROM Hobbs 1986

WATER CONTENT, % OF DRY WEIGHT

0 200 400 600 800 1000 1200 1400 16000

10

20

30

40

50

60

70

80

90

100 0

10

20

30

40

50

60

70

80

90

100

von

Pos

t No

(H)

0

2

4

6

8

10

Miyakawa, 1960

MacFarlane& Rutka, 1962

'ASH' CONTENT

von Post No (H)A

B

CO

RG

AN

IC C

ON

TEN

T (

%)

ASH

CO

NTE

NT (

%)

Fine-grained soils(F>50%, Oc≤10%)

Non organic soils(Oc<3%)

Slightly organic soils [fO] (3%<Oc<10%)

Clay or silt of high or lowplasticity (from wL & IP values) CL CH ML MH

Slightly organic, silty or clayey soil of low or high plasticity (from wL & IP values) COL COH MOL MOH

Organic soils [O](Oc=10-60%)

Medium organic soils [mO] (10%<Oc≤30%)

Medium organic soil with -amorphous [mO-a]-semi-fibrous [mO-sf]-fibrous [mO-f]

organic matter

Highly organic soils [hO] (30%<Oc<60%)

Highly organic soil with -amorphous [hO-a]-semi-fibrous [hO-sf]-fibrous [hO-f]

organic matter

Peaty organic soils, peaty soils, peats(Oc≥60%)

Peaty organic soils [PtO] (Oc=60-80%)Peaty soils, peats [Pt] (Oc>80%)

Peaty organic soil with -amorphous [PtO-a]-semi-fibrous [PtO-sf]-fibrous [PtO-f]

organic matter

Peaty soils and peats with -amorphous [Pt-a]←”dy”-semi-fibrous [Pt-sf]-fibrous [Pt-f]

organic matter

Symbols: Oc – organic content, F – content of particles finer than #200 sieve, C – clay, M - siltThe classification of organic matter is based on the von Post index: H1 to H3: fibrous organic matter, H4 to H6: semi-fibrous organic matter, H7 to H10: amorphous organic matter

PROPOSED CLASSIFICATION SYSTEM FOR ORGANIC SOILSPROPOSED CLASSIFICATION SYSTEM FOR ORGANIC SOILSBased on von Post 1922, Casagrande 1948, Perrin 1974, Magnan 1980, Landva et al. Based on von Post 1922, Casagrande 1948, Perrin 1974, Magnan 1980, Landva et al.

19831983

MINERAL CONTENT (% BY WEIGHT)5 10 15 20

200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400WATER CONTENT (% BY WEIGHT)

PEAT TYPE

(FIELD CLASSIFICATION)

DE

PT

H(m

)

1

2

3

4

5

6

MINERAL CONTENT

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

H

= HILLER SAMPLER= 50mm PISTON SAMPLER

SH B F R4 4 1 1

SH B F R2-3 3 1 1

SH B F R5-6 4 1 1

SH B F R (N)2 4 1 1

SH B F R3 4-5 1 1

SH B F R (N)2-3 4 1 1

SH B F R3 3 1 1

SH B F R2 4-5 1 1

SCH B F R3 4 2 1-2

SCH B F R (N)3 4 2 2

SCH B F R3-4 4 2 2

SCH B F R3-4 5 2 2

SCH B F R (N)5 4 2-3 2

SCH B F R (N)6 4 2-3 2

SCH B F R (w)7 4 1 1

SCH B F R6 4 1 1

ErCSH B F R (w )2 4 1 1

ESCUMINAC PEAT BOG, NBESCUMINAC PEAT BOG, NB (Landva and Pheeney 1980)(Landva and Pheeney 1980)

ESCUMINAC RAISED PEAT BOG, NBESCUMINAC RAISED PEAT BOG, NB(DRIVING ON WATER?)(DRIVING ON WATER?)

VA= 0.05

Water

Organic

solids

Gas

VS= 0.04

Vw= 0.91

Vv= 0.96

V = 1

n =Vv

V = Vv if V = 1

Sr =Vw

Vv

= 0.95 = Vwn

e = Vv

VS

= 24

n =2425

= 0.96

VW = nSr = 0.96 x 0.95 = 0.91

PHASE DIAGRAM

!!

PEAT UNDER A MICROSCOPE PEAT UNDER A MICROSCOPE

500 mm 100 mm 50 mm

25 mm 5 mm 50 mm

SH1 leaf SH1 leaf SH1 stem

SH1 leaves SH1 leafSH1 apical bundle

100 mm 100 mm 100 mm

200 mm100 mm 100 mm

SH3 peatSH3 compressed under 7000 kPaSH4 stem

Classified as SH8. Alternatinglayers/lenses of SH9-10 and SH3-5

ErH8 sedge sheath ErH8 sedge sheaths

PEAT UNDER A MICROSCOPE PEAT UNDER A MICROSCOPE

HALL’S CREEK ORGANIC SOILHALL’S CREEK ORGANIC SOILBORELOG FROM TEST FILL AREABORELOG FROM TEST FILL AREA

(Keenan et al. 1986)(Keenan et al. 1986)

BS9 1978UNB 1 1983UNB 2 1983

UNB 3 1983

SAND-4.0

ORGANIC CLAYEYSILT (CLAY SIZECONTENT 43-49%)

GRANULAR FILLACCESS

DESCRIPTION

GWL

WWLWP

WATER CONTENT %20 40 60 80 100

SHEAR STRENGTH kPa

10 20 30 40 50 60 70 80 90DE

PT

H

0

1

2

3

4

5

6

7

8

9

10

11

EL

EV

AT

ION

ME

TR

E

7.5

6.9

OR

GA

NIC

C

ON

TE

NT

%

4-6

4-6

5-6

200 400 600 800

CONE PENETRATIONRESISTANCE kPa

0

5

10

15UNCONFINED COMPRESSION(STRAIN AT FAILURE 0-20%)UNB 1 & UNB 2

AVERAGE SHEAR STRESS AT FAILURE OFTEST FILL

RANGE OF RECORDED SHEARSTRENGTH (VANE) SU

P'a EFFECTIVEOVERBURDEN PRESSURE

T

TTRANGE OF REMOLDED SHEARSTRENGTH (VANE) Sr

RANGE OF qC

T

T

T

SIMPLE SHEAR

DIRECT SHEAR OSI

T TRIAXIAL TEST & T PLOTTED AT DEPTH CORRESPONDING TO

(σc at p’a)σc = p’0

MIRAMICHI CHANNEL STUDYMIRAMICHI CHANNEL STUDY(ADI 1976)(ADI 1976)

2.73

2.69

2.71

2.72

SPECIFIC GRAVITY

CO

MB

-U

ST

ED

a

b

c

d

e

f

SA

MP

LE

TY

PE

1 H2 H3 H4 H5 H6 H7 H8 H

10 H

11 H

9 H

SA

MP

LE

NO

SOIL DESCRIPTION

ORGANICDIATOMACEOUS CLAYEY SILT

DE

PT

H B

EL

OW

SE

A B

OT

TO

M,

m 1

2

3

4

5

6

100 200w%

5 10 15 20 25ORGANIC CONTENT (% BY WT.)

a. Black ooze, strong odourb. Black layers, some seaweed and shells, strong odourc. Grey, black streaks, some shells, some odourd. Grey, horizontal dark grey bands, slight odoure. Grey, small shells throughout, no odourf. Grey, black streaks, no odour

Water contentOrganic contentAtterberg limits

Location: South Miramichi Channel Boring No.: H3 Date drilled: JULY 28, 1976 Project: Miramichi Inner Bay

Water Depth appprox. 5.8 m BORING LOG

Hiller peat samplerH

w

Oc

SUMMARY OF SOIL PROPERTIES AT THE SUMMARY OF SOIL PROPERTIES AT THE VVÄÄSBY TEST FIELDS (Chang 1981)SBY TEST FIELDS (Chang 1981)

DESCRIPTION

BROWN GREY CLAYWITH ORGANIC ODOR

BLACK CLAY WITHSULFIDES AND ORGANIC COLLOIDS

GREY UNIFORMCLAY

GREY CLAY WITHDIFFUSED VARVES

GREY CLAY WITHDISTINCT VARVES

SAND

ROCK

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Depthm

WATER CONTENT40 60 80 100 120 IP%

IL0.8 1.0 1.2 GS 12 14 16 18 20

87

85

87

79

72

65

59

53

48

47

48

48

34

2.63

2.70

5.4

3.7

1.8

0.4

0.8

3.0

2.2

2.0

1.3

NO

T D

ETE

RM

INE

DO

RG

AN

IC *

*C

ON

TE

NT

OR

GA

NIC

**

CO

NT

EN

T

SV

SV = field vane shear strength, kPa

CONSOLIDATION TESTS ON CONSOLIDATION TESTS ON UNDISTURBED AND REMOULDED PEATUNDISTURBED AND REMOULDED PEAT

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.01 2 3 4 5 10 20 50 100 500 1000 10000

P-82

P-66

P-68P-82

P-67

a

b

P-67 SH3 UNDISTURBED wi = 1380%, wf = 692% P-66 SH3 UNDISTURBED wi = 1242%, wf = 646% D = 100 mm, ho = 62.5 mm

a-b Special consolidation test in thick-walled ring

*consolidated from slurry(w 3000%)

P-82 SH3 REMOULDED* wi = 1242%, wf = 646% D = 100 mm, ho = 62.5 mm

P-68 SH3 UNDISTURBED wi = 1381%, wf = 819%

VE

RT

ICA

L S

TR

AIN

, ε v

APPLIED PRESSURE, kPa

1

1 10 10040

30

20

10

0

1

mv

40

30

20

10

0

0 25 50 75 100

1.00 25 50 75 100

1

av

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

1 10 100

1

ALTERNATIVE PLOTS OF STRAIN OR VOID ALTERNATIVE PLOTS OF STRAIN OR VOID RATIO VS STRESS OR LOG STRESSRATIO VS STRESS OR LOG STRESS

Voi

d r

atio

, e

Effective consolidation stress, σ’vc (kPa) Effective consolidation stress, σ’vc (kPa)

Voi

d r

atio

, e

Effective consolidation stress, σ’vc (kPa) Effective consolidation stress, σ’vc (kPa)

Ver

tical

Str

ain,

εv

Ver

tical

Str

ain,

εv

S=HmvΔσ=HΔε S=HCcεlogσo’+Δσ

σo’

Ccε

Cc

(eo, σo’)(eo, σo’)

S=Hav

1+eo

Δσ S=HCc

1+eo

logσo’+Δσ

σo’

““THE LOG TRAP”THE LOG TRAP”

1 10 100

40

30

20

10

0

50

1 10 100

40

30

20

10

0

50

Effective consolidation stress σ’ (kPa) Effective consolidation stress σ’ (kPa)

ε v (

%)

ε v (

%)

σ’=30-34 kPa

““THE LOG TRAP”THE LOG TRAP”

1 10 100

40

30

20

10

0

50

Effective consolidation stress σ’ (kPa)

ε v (

%)

σ’=30-34 kPa

30

20

10

0

40

500 25 50 75 100

σ’=30-34 kPa

Effective consolidation stress σ’ (kPa)

ε v

(%)

TIME

EF

FE

CT

IVE

ST

RE

SS

DELAYED

INSTANT

SECONDARY

PRIMARY

PERIOD OF PORE

PRESSUREDISSIPATION

NO EXCESSPORE PRESSURE

CO

MP

RE

SS

ION

INSTANT/DELAYED VS PRIMARY/SECONDARY INSTANT/DELAYED VS PRIMARY/SECONDARY MODES OF COMPRESSION (BJERRUM 1967)MODES OF COMPRESSION (BJERRUM 1967)

1.2

1.3

1.4

1.5

1.610 20 50 150 300

VERTICAL PRESSURE (kPa)

100V

OID

RA

TIO

, e Instant compressionduring sedimentation

Delayed compression

eo po

Equilibrium void ratio at diff. time of sustainedloading

Instant

After 30 years

ed

pc

3 years303003000

COMPRESSIBIITY OF A CLAY EXHIBITING DELAYED COMPRESSIBIITY OF A CLAY EXHIBITING DELAYED CONSOLIDATION (BJERRUM 1967)CONSOLIDATION (BJERRUM 1967)

LABORATORY CONSOLIDATION, SHLABORATORY CONSOLIDATION, SH33 PEAT PEAT (Landva 1980)(Landva 1980)

1 2 1005010543

0.1

0.2

0.3

0.4

0.5

0.6

0.7

APPLIED PRESSURE, kPa

60600

6000

60000 min

Cc'=0.58

SH3 UNDISTURBEDWi = 1242%Wf = 646%D = 100 mmho = 62.5 mm

VE

RT

ICA

L S

TR

AIN

εv

CONSOLIDATION TESTS ON UNDISTURBED SHCONSOLIDATION TESTS ON UNDISTURBED SH33 PEATPEAT

1 10 100 1000 10,000 100,0000

0.10

0.20

0.30

0.40

0.50

0.60

0-2.7 kPa

2.7-6.8 kPa

6.8-13.6 kPa

13.6-20.3 kPa

20.3-27.5 kPa

27.5-34.2 kPa34.2-41.5 kPa

0-40 kPa

TIME, minutes

P-67 SH3 Undisturbed Wi = 1380% Wf = 692 % D = 100 mm ho = 58.9 mm

P66 - (single step)

P67 - (multistep)

VE

RT

ICA

L S

TR

AIN

εv

Cα=0.025

Cα=0.024

Cα=0.025

Cα=0.020

Cα=0.022

Cα=0.025

Cα =0.105

Cα=0.043

Cα=0.015

Cα=0.004

Cα=0.005

SETTLEMENT OF ESCUMINAC TEST FILLSSETTLEMENT OF ESCUMINAC TEST FILLS

0

1

2

3

4

5

6

7

0.1 1 10 100 1000 10,000TIME (days)

SE

TT

LE

ME

NT

(m

)

0.028TF8 85-76 kPa

0.033

0.032

TF6a 60-46 kPa

TF9 45-33 kPa

TF3 12-11 kPa

COEFFICIENT OF SECONDARY COMPRESSION COEFFICIENT OF SECONDARY COMPRESSION CCαεαε VERSUS COMPRESSION INDEX CVERSUS COMPRESSION INDEX Cc c (Lefebvre et al. (Lefebvre et al.

1984)1984)

INCREMENTAL TESTS NBR-2

STAGE CREEP TESTS NBR-2

INCREMENTAL TESTS NBR-3

COMPRESSION INDEX CC

CO

EF

FIC

IEN

T O

F S

EC

ON

DA

RY

CO

MP

RE

SS

ION

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Cα

ε

C αε/C

c =

0.1

1

C αε/C

c =

0.0

6

C αε/C c

= 0.033

EMBANKMENTS ON PEAT (Weber 1969, Hobbs EMBANKMENTS ON PEAT (Weber 1969, Hobbs 1986)1986)

5 10 15 20 25LOADING IN TOTAL THICKNESS OF FILL - FEET From Weber 1969

10

0

20LO

NG

TE

RM

SE

TT

LE

ME

NT

-P

ER

CE

NT

PE

R L

OG

CY

CL

E

5 10 15e

0.5

1

020

From Hobbs 1986

Cc

1+eo

200-350%350-500%>500%

Cα

1 10 102 103 104 105 10610-110-210-3

A

B

H1 (lab) H2 (field)

tP1Vanishingly thinlayer at A

Time (t) (minutes)

tP2

tP2 = tP1 H2

H1

2 k1

k2

approximately

"stately march"

STRAIN VS LOG TIME FOR TWO DIFFERENT STRAIN VS LOG TIME FOR TWO DIFFERENT THICKNESSES OF PEAT UNDER THE SAME THICKNESSES OF PEAT UNDER THE SAME

LOADLOAD(From Hobbs 1986)(From Hobbs 1986)

Str

ain

(ε)

COEFFICIENT OF SECONDARY COMPRESSION COEFFICIENT OF SECONDARY COMPRESSION VERSUS WATER CONTENT FOR MIRES AND CLAY VERSUS WATER CONTENT FOR MIRES AND CLAY

(Hobbs 1986)(Hobbs 1986)

Water Content (%)

0 500 1000 1500 2000

0

0.01

0.02

0.03

0.04

0.05

Co

effi

cie

nt

of

Se

co

nd

ary

Co

mp

res

sio

n C

sec

Norfolk (buried peat)

Weber (1969) San Francisco

Cheshire poor fen

Sizewellacid fen

Welsh bog

Shropshire fen & transition peat

Simons (1974)

clay

s

Range deducedfrom Cc

British Columbia

SETTLEMENT BENEATH EMBANKMENTS ON SETTLEMENT BENEATH EMBANKMENTS ON PEATPEAT

1.6

4.2(1)

Escuminactest fills

Settlement under widefills

1.6

1.9

0.50.2

0.2

3.6

0.5

0.30.6

0.6

1.10.05

Escuminac1967 road

0.2 years

4 years40 years

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.00 10 20 30 40 50 60 70 80 90 100

Hobbs 1986, Landva 1980aNBR2NBR3Samson & La Rochelle (1972) P1 peat category IISamson & La Rochelle (1972) P3 peat category IIEggestad & Foyn (1977)Ripley & Leonoff (1961) peat category 4-6Royer (1936) peat and clay

Applied pressure, kPa

1.10.8

0.90.04

2.2Gautschi (1965) H2-9 peat

UNB 100 mm dia. lab testssphagnum H3 peat

Ver

tical

str

ain,

εv

ESCUMINAC TEST FILLSESCUMINAC TEST FILLS

0 1 2 3 4 5

-1

1

2

3

4

5

6

7

8 m

0

TF9TF6a

CL

End of construction

After 12 years

SECTIONS THROUGH SECTIONS THROUGH LARGE TEST FILL LARGE TEST FILL

(Landva 1980)(Landva 1980)

-1

0

1

2

3

4

5

6

7

8

9CL

EL

EV

AT

ION

, m

TF7CL

PEAT

TILL

Original bog level

b

1979

a

FILL

End of construction

TF80 1 2 3 4 5 10m

Bulging of peat due to shear deformation

After heave

Ground water level

-1

0

1

2

3

4

5

6

7

8

9E

LE

VA

TIO

N,

m

End of construction

0.3 m rockfill

Original bog level

SUMMARY OF SETTLEMENT DATA (Scotton, SUMMARY OF SETTLEMENT DATA (Scotton, 1981)1981)

“In common use by many geotechnical engineers on the west coast”

Escuminac test fills

RATIO PRIMARY SETTLEMENT: ORIGINAL PEAT DEPTH - S/P

RA

TIO

FIL

L H

EIG

HT:

OR

IGIN

AL

PE

AT

DE

PT

H -

H /

P

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

H

P

P 1.5m

SYMBOLAVERAGE INITIALWATER CONTENT

LESS THAN 400%400 - 600%600 - 800%MORE THAN 800%

0.2 0.4 0.6 0.8

NBR-3 NBR-2

Autoroute de la Rive Nord, P.Q.

S

Scotton 1981

S/H=0.27

S/H=0.63

S/H=1.15

AP

PL

IED

LO

AD

, kP

a

0

20

40

60

80

1 2 5 10 20 50 100 200 500 1000 2000 5000TIME, DAYS

SURCHARGESTAGE

FINALSTAGE

2nd LOADINGSTAGE

1st LOADINGSTAGE

YEARS 1964 1965 1966

1 2 5 10 20 50 100 200 500 1000 2000 5000

1st LOADINGSTAGE

2nd LOADINGSTAGE

SURCHARGESTAGE

0

0.1

0.2

0.3

0.4

0.5

0.6

NOSURCHARGE

0.7

6500

PAVING

0.25 mSamson 1985

Ca =0.045

NOSURCHARGE

SURCHARGE ON PEAT SURCHARGE ON PEAT (Samson 1985, Samson and La Rochelle 1972)(Samson 1985, Samson and La Rochelle 1972)

0.25 mPEAT

SAND

Surcharge

Pavement

+15

+25

+20

WITH SURCHARGE

NO SURCHARGE

VE

RT

ICA

L S

TR

AIN

, ε v

PRECONSOLIDATION DEFINED IN TERMS OF VOID PRECONSOLIDATION DEFINED IN TERMS OF VOID RATIO (From Lefebvre 1986)RATIO (From Lefebvre 1986)

ep

e

logσv’

CαOC

CαNC

EXPRESSWAY “AUTOROUTE DE LA RIVE EXPRESSWAY “AUTOROUTE DE LA RIVE NORD” P.Q.NORD” P.Q.

VA= 0.04

Water

Organic

solids

Gas

VS= 0.16

Vw= 0.80

Vv= 0.84

V = 1

n =Vv

V = Vv if V = 1

Sr =Vw

Vv

= 0.96 = Vwn

e = Vv

VS

= 5.1

n =5.16.1

= 0.84

VW = nSr = 0.84 x 0.96 = 0.80

PHASE DIAGRAM

JAMES BAY, P.Q. NBR-2 PEAT (Lefebvre et al. JAMES BAY, P.Q. NBR-2 PEAT (Lefebvre et al. 1984)1984)

NB2-80-COE-01-U-K 0.20NB2-80-COE-03-U-K 0.50NB2-81-COE-04-U-CP-K 0.50NB2-81-COE-05-R-K 0.50NB2-81-COE-08-U-K 1.75

TEST No. DEPTH (m)

COEFFICIENT OF PERMEABILITY k (cm/s)

VO

ID R

AT

IO e

2

4

6

8

10

12

14

16

18

20

22

1x10-9 1x10-8 1x10-7 1x10-6 1x10-5 1x10-4 1x10-3

Several dams & dikes are founded on peat in Alberta and B.C.

MIRAMICHI LAGOON BERM ON DIATOMACEOUS MIRAMICHI LAGOON BERM ON DIATOMACEOUS ORGANIC SILT ORGANIC SILT

0 50 100 150 200 250 3000

25

50

75

100

125

150

175

350

300

250

200

150

100

50

0

TIME (days)

EX

CE

SS

PO

RE

WA

TE

R P

RE

SS

UR

E(k

Pa)

SE

TT

LE

ME

NT

(m

m)

El. +2.0m (top of toe berm)

Excess pore pressure

Settlement

El. +5.4m El. +5.1m

Embankment(elevation as noted)

Δumax≈75 kPaΔσmax≈80 kPa

CONSOLIDATION MODEL ICONSOLIDATION MODEL I

CONSOLIDATION MODEL IICONSOLIDATION MODEL II

Springs displaying plastic behaviour

CONSOLIDATION MODEL IIICONSOLIDATION MODEL III

PEAT CLIFF FAILURES, ESCUMINAC, NBPEAT CLIFF FAILURES, ESCUMINAC, NB(Landva 2007)(Landva 2007)

PLATE LOAD TESTS IN INTACT AND IN PRECUT PLATE LOAD TESTS IN INTACT AND IN PRECUT PEAT, ESCUMINAC, NB PEAT, ESCUMINAC, NB

MAT30 cm

16.5 cmdia.

46 cmPrecut aroundthe plate to 46 cm depth

NUMBERS ON CURVES ARE VERTICALSTRESS in kPa

Failure

41

34

27

20

147

41

34

27

20

14

0

2

4

6

8

10

0 10 20 30 40 50TIME, (minutes)

SP200-1, Undisturbed peat in 0.3 m pit (MAT removed)SP200-2, Peat cut to 46 cm depth around 16.5 cm dia. plate

SE

TT

LE

ME

NT

δ (

cm)

MAX δ = 10cm (failure)

SHEAR FAILURE PATTERNS RECORDED ON SHEAR FAILURE PATTERNS RECORDED ON OUTER SURFACE IN RING SHEAR TESTSOUTER SURFACE IN RING SHEAR TESTS

SHEAR

PLANE

SHEAR

PLANE

RING SHEAR

σva

Τ

RING SHEAR TEST OF FIBROUS SOILRING SHEAR TEST OF FIBROUS SOILCircle 1 = consolidation under sva andKosva = (1-sinf)sva

Circle 2 = initial attempted failure along yz at end of pure shearCircle 3 = final failure in simple shear along st

0-20 1008040 60

(ring shear)

s

20

c 140120 160

Failure plane

in ring shearRING SHEAR t

1y

2

3

z

d

40

σva

Τ

Τy

Τs

c=3 kPa, Ф=30o

σ (kPa)σva

Τ (

kPa)

δh

ΤΤs

Τy

““TENSILE” TEST OF FIBROUS SOIL – TENSILE” TEST OF FIBROUS SOIL – CONSOLIDATION STAGE CONSOLIDATION STAGE

Equipment designed for measurement Equipment designed for measurement of tensile strengthof tensile strength

0-20 1008040 60

20

140120 160

4

1

a

b(a)

(b)

Τ (

kPa)

σ (kPa)σvaσha σfr

σva

σfr σha

σva = applied vertical stress in confined compressionσfr = fibre resistance during consolidationσha =0.2σva= applied lateral confinement stress (at εh=0)

Circle 1 = consolidation under σva and σha+σfr

where σha+σfr = Ko σva = (1-sinФ)σva (as before) Circle 4 = externally applied stresses

(i.e. apparent consolidation circle)

““TENSILE” TEST OF FIBROUS SOILTENSILE” TEST OF FIBROUS SOIL

-σta = externally applied tensile stressσfrf = fibre resistance at failure

0-20 1008040 60

(ring shear)

20

c 140120 160

1

6

d

2

a

b

7

5

Τ (

kPa)

σ (kPa)σva

σva

σtaσfrf

α

α=45o+Ф

α=60o

-σta σfrf

c=3 kPa, Ф=30o

Circle 1: consolidation (as before)Circle 5: usually - but mistakenly - assumed to represent tensile failure on vertical plane abCircle 6: shear failure on planes at 45 + Ф/2to horizontalCircle 7: apparent failure circle (externally

applied stresses σva and -σta)α

DIRECT AND SIMPLE SHEAR TESTS ON FIBROUS DIRECT AND SIMPLE SHEAR TESTS ON FIBROUS PEAT (From Rowe et al. 1984)PEAT (From Rowe et al. 1984)

0 10 20 30 40 500

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

0 4 8 12 160

5

10

15

20

25

30

35

40

45

50

SHEAR STRAIN (%) HORIZONTAL STRAIN (%)

SH

EA

R S

TR

ES

S,

(kP

a)

SH

EA

R S

TR

ES

S,

(kP

a)

SAMPLE SIZE:80 mm DIA.18 mm Nominal HeightFeed Rate:0.0472 mm/minPEAT:H4-6B3F2R1-2

Wn=52%

=31.5 kPa

21.5 kPa

21.5 kPa

11.0 kPa

11.0 kPa

2.5 kPa

2.5 kPa

SAMPLE #1

#2

#3

#4

#5

#6

#7

=71 kPa

52 kPa

34 kPa

16 kPa11 kPa6 kPa

ASSUMED FAILURESAMPLE 60 mm x 60 mmFeed:0.0609 mm/minPeat:H4-6B3F2R1-2

Wn=539%

DIRECTSHEAR

DIRECTSIMPLESHEAR

σn’

σn’

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

STAGE 1-2, PURE SHEARSTAGE 1-2, PURE SHEARFAILURE PLANE FP 1-2FAILURE PLANE FP 1-2

2010 30 40

10

20

FP1-2

1

2

0 5 10 15 20 25

10

20

PP2

PP1

1

2

PP = POLE POINT

H

c=2.5 kPa, Ф=30o

Τ (

kPa)

Τ (

kPa)

ε (%)

εs = δh

Hσv

δh Τ

σ (kPa)

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

FINAL STAGE 4-5FINAL STAGE 4-5FAILURE PLANE FP 4-5 (horizontal)FAILURE PLANE FP 4-5 (horizontal)

2010 30 40

10

20

FP4-5

5

0 5 10 15 20 25

10

20

1

PP5

1

4

3

2

5

Τ (

kPa)

σ (kPa)

Τ (

kPa)

ε (%)

σv

Τ

c=2.5 kPa, Ф=30o

CD1

CD3

c=4 kPa,

c=6 kPa,

CCV1CCV3

CAU1CCV4

= maximum shear stress applied= initial failure in pure (simple) shear

CAU2

CAU3

0 10 20 30 40 50 60 70 80 90 100 110

10

20

30

40

50

60

CD2

CCV2

MIRAMICHI BAY MUD, NB, MIRAMICHI BAY MUD, NB, TRIAXIAL AND SIMPLE SHEAR RESULTSTRIAXIAL AND SIMPLE SHEAR RESULTS

CAU - anisotropically consolidated, undrained triaxial testCCV - anisotropically consolidated, constant volume simple shear test CD – anisotropically consolidated, drained simple shear test

C≈3-1

0 kP

a

Ф≈4

0o -5

3o

She

ar s

tres

s Τ

(kP

a)

Effective stress σ’ (kPa)

Ф=18o

Ф=23o

0 100 200 300

100

200

kPa

kPa

=108=266

=52=57

=18

=21

1 21

1

22

only

Miramichi Harbour mud

Direct simple shear tests

Mexico City

Soil

Triaxial t

ests (L

o 1962)

fr 2 fr 1

TRIAXIAL AND SIMPLE SHEAR TESTSTRIAXIAL AND SIMPLE SHEAR TESTSDIATOMACEOUS ORGANIC CLAYEY SILTDIATOMACEOUS ORGANIC CLAYEY SILT

σ

Τ

σva σva

σha

σha

σfr σfr c=6 kP

a,Ф=40

o

c=6 kPa,Ф=23o

c t=0,Ф=12o

σ σ

100 mm

MIRAMICHI BAY MUDMIRAMICHI BAY MUDScanning Electron Microscope (UNB 1997)Scanning Electron Microscope (UNB 1997)

MEXICO CITY SOIL (Mesri et al. 1975)MEXICO CITY SOIL (Mesri et al. 1975)Composition of Mexico City Clay consists of about 5-10% sand-Composition of Mexico City Clay consists of about 5-10% sand-

sized concretionary particles of ooliths composed of calcium sized concretionary particles of ooliths composed of calcium carbonate; 55-65% silt-sized siliceous diatoms; 20-30% clay carbonate; 55-65% silt-sized siliceous diatoms; 20-30% clay

sized particles of which probably 10% is interlayered smectite sized particles of which probably 10% is interlayered smectite and the remaining is biogenic or volcanogenic silica; and 5-10% and the remaining is biogenic or volcanogenic silica; and 5-10%

organic material. The basic characteristics of the siliceous organic material. The basic characteristics of the siliceous diatoms, interlayered smectite and organic matter combine to diatoms, interlayered smectite and organic matter combine to

give Mexico City clay its unusual physical properties. give Mexico City clay its unusual physical properties.

RELATIONSHIP BETWEEN SRELATIONSHIP BETWEEN Suu//ss’’pp AND AND PLASTICITY INDEX (modified from Tavenas & PLASTICITY INDEX (modified from Tavenas &

Leroueil 1987)Leroueil 1987)

Skempton (1957)

Bjerrum (1973)

0

0.2

0.4

0 20 40 60 80 100

Inorganic claysEastern CanadaOthers

Organic clays

Plasticity Index, Ip (%)

Su (

van

e) /

σ’ vo

CORRECTION FACTOR VERSUS PLASTICITY INDEX CORRECTION FACTOR VERSUS PLASTICITY INDEX FOR UNDRAINED SHEAR STRENGTH FROM VANE FOR UNDRAINED SHEAR STRENGTH FROM VANE

SHEAR TEST (modified from Ladd et al. 1977)SHEAR TEST (modified from Ladd et al. 1977)Halls Creek Halls Creek test fill test fill failure:failure:F=2.5 F=2.5 based on based on vane vane strength*, strength*,

*Keenan et *Keenan et al. 1986al. 1986

i.e. i.e. mm≈0.25≈0.25

0.4

0.6

0.8

1.0

1.2

1.4

0 20 40 60 80 100 120

Plasticity Index, Ip (%)

Va

ne

Co

rrec

tio

n F

acto

r,

Su (field) = Su(vane)

Bjerrum (1972)

Halls Creek

μ

μ

POTENTIAL FAILURE MECHANISM DUE TO POTENTIAL FAILURE MECHANISM DUE TO LATERAL THRUST AND SLIDING ON A DEEPER LATERAL THRUST AND SLIDING ON A DEEPER

LOW STRENGTH LAYER (after Rowe 2001) LOW STRENGTH LAYER (after Rowe 2001)

x

H

PeatD

Active Earth Pressurein Fill

Treq = Force Developed in reinforcement

Active Earth Pressurein Peat (mostly dueto vertical stressimposed by the fill)

Positive EarthPressure in Peatdue to Peat self weight

Very Soft Clay

Su Shear Strength at (or near)Peat/Very Soft Clay Interface

Treq

Z

Sr

Sr = settlement duringconstruction

POSSIBLE SEVERING OF MAT AT LEFT EDGE OF POSSIBLE SEVERING OF MAT AT LEFT EDGE OF RIGID BASE (CORDUROY) REINFORCEMENT RIGID BASE (CORDUROY) REINFORCEMENT

EMBANKMENT ON PEAT BEFORE AND AFTER EMBANKMENT ON PEAT BEFORE AND AFTER WIDENING WIDENING

(b) additional pressure on peat at end of construction (after (b) additional pressure on peat at end of construction (after

widening)widening)

(a) settlement and cracking after widening(a) settlement and cracking after widening

BEFORE WIDENING

AT END OF CONSTRUCTION (AFTER WIDENING)

AFTER FURTHER SETTLEMENT

ADDITIONAL PRESSURE ON PEATAT END OF CONSTRUCTION (AFTER WIDENING)

(a)

(b)

CUSH ROAD (IRELAND) SECTION BEFORE AND CUSH ROAD (IRELAND) SECTION BEFORE AND AFTER WIDENING (after Hanrahan 1964) AFTER WIDENING (after Hanrahan 1964)

PEAT BALES

EMBANKMENT ASOBSERVED 1962(PEAT BALES PLACEDIN 1954, REPLACINGGRAVEL)

BEFORE BAILING

ASSUMED BASE ELEVATIONORIGINALEMBANKMENTA

AC

BB

A GRAVEL ROAD TO 1936, SURFACED WITH TARMACADAM IN 1936. LIGHT TRAFFIC 1940-1953.B PROPOSED (1952) WIDENING AND ROLLING IN GRAVEL IN STRIPS 18 INCHES THICK EXCAVATED AT EACH SIDE OF THE ROAD.C PROPOSED (1952) ADDITIONAL THICKNESS OF 18 INCHES OF GRAVEL. 0 1 2 3 4 5m

0

1

2

3

4

5

6

7

m

0 1000 2000w%

Sphagnum peat

Sphagnum - sedge peat

CorduroyPeat mat

OLD ROAD (CA. 1870), ESCUMINAC, NBOLD ROAD (CA. 1870), ESCUMINAC, NB

OLD ROAD (CA. 1870) AT ESCUMINAC, NBOLD ROAD (CA. 1870) AT ESCUMINAC, NBERODED BY WAVESERODED BY WAVES

OLD ROAD (CA. 1870) AT ESCUMINAC, NBOLD ROAD (CA. 1870) AT ESCUMINAC, NBERODED BY WAVESERODED BY WAVES

OLD ROAD (CA. 1870) AT ESCUMINAC, NBOLD ROAD (CA. 1870) AT ESCUMINAC, NBERODED BY WAVESERODED BY WAVES

Pump

Drains

Membrane

Filter

CONSOLIDATION OF CLAY SOIL BY MEANS OF CONSOLIDATION OF CLAY SOIL BY MEANS OF ATMOSPHERIC PRESSURE (W. Kjellman, 1948)ATMOSPHERIC PRESSURE (W. Kjellman, 1948)

““The cost of using the vacuum method is nearly independent of the desired intensity of the The cost of using the vacuum method is nearly independent of the desired intensity of the surcharge. Therefore, the vacuum method can best compete with the sand layer method when the surcharge. Therefore, the vacuum method can best compete with the sand layer method when the desired surcharge is great. This occurs when time is scarce, and also when the structure is heavy. desired surcharge is great. This occurs when time is scarce, and also when the structure is heavy. It may also occur when a deep excavation is to be made.It may also occur when a deep excavation is to be made.

A great surcharge of sand on a soft clay must be applied slowly, lest the ground fail. If vacuum is A great surcharge of sand on a soft clay must be applied slowly, lest the ground fail. If vacuum is used instead of sand, ground failure is impossible, and many months may be saved.used instead of sand, ground failure is impossible, and many months may be saved.

A surcharge of sand cannot be used at all for stabilizing an existing slope or shaft, because it would A surcharge of sand cannot be used at all for stabilizing an existing slope or shaft, because it would cause a slide. Vacuum, on the contrary, can well be applied in such cases.”cause a slide. Vacuum, on the contrary, can well be applied in such cases.”

MASS MASS STABILIZATIOSTABILIZATIO

N OF PEAT N OF PEAT (Jelisic and (Jelisic and LeppLeppäänen nen

1999)1999)

MIRAMICHI CHANNEL MIRAMICHI CHANNEL FULLY LOADED COAL FREIGHTER OBSERVED FULLY LOADED COAL FREIGHTER OBSERVED

PLOWING THROUGH “MUD” OUTSIDE DREDGED PLOWING THROUGH “MUD” OUTSIDE DREDGED CHANNELCHANNEL

qc kPa

0 200 400

10

20ft

MS Queen Mira

510

202530

DEPTH OF WATER: 20 ftDRAFT OF SHIP: 26 ft"MUD" = DIATOMACEOUS ORGANIC CLAYEY SILT

ft

TerrAtlanticEngineering Limited

• Geotechnical Engineering • Hydrogeology• Environmental Engineering

515 Beaverbrook CourtFredericton, New BrunswickCanada, E3B 1X6

www.terratlantic.nb.caTel: (506) 460-8660Fax: (506) 460-8679

This presentation is available on our website.

Sponsors For Cross Canada Lecture Tour, Spring 2009

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Bibliography Bibliography and Supplementary Slidesand Supplementary Slides

BIBLIOGRAPHYBIBLIOGRAPHY Adams, J.I. 1965. The engineering behaviour of a Canadian muskeg. Proc. 6th Int. Conf. SMFE, vol. I.Adams, J.I. 1965. The engineering behaviour of a Canadian muskeg. Proc. 6th Int. Conf. SMFE, vol. I. ADI Limited 1976. Miramichi Channel Study report.ADI Limited 1976. Miramichi Channel Study report. Berry, P.L. and Poskitt, T.J. 1972. The consolidation of peat. Géotechnique, 22, 1.Berry, P.L. and Poskitt, T.J. 1972. The consolidation of peat. Géotechnique, 22, 1. Bjerrum, L. and Landva, A. 1966. Direct simple-shear tests on a Norwegian quick clay. Géotechnique 16, 1.Bjerrum, L. and Landva, A. 1966. Direct simple-shear tests on a Norwegian quick clay. Géotechnique 16, 1. Bjerrum, L. 1967. Engineering geology of Norwegian normally-consolidated marine clays as related to settlement of buildings. 7th Bjerrum, L. 1967. Engineering geology of Norwegian normally-consolidated marine clays as related to settlement of buildings. 7th

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University, Lafayette, Ind. Proc., vol. 2.University, Lafayette, Ind. Proc., vol. 2. Bjerrum, L. 1973. General report to: Session 4. Problems of soil mechanics and construction on soft clays and structurally unstable soil. Bjerrum, L. 1973. General report to: Session 4. Problems of soil mechanics and construction on soft clays and structurally unstable soil.

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((EdEd.), ASTM Committee D-18 Symposium, Toronto, Canada, pp. 37-51..), ASTM Committee D-18 Symposium, Toronto, Canada, pp. 37-51. Landva, A.O. and La Rochelle, P. 1983. Compressibility and shear characteristics of Radforth peats. Landva, A.O. and La Rochelle, P. 1983. Compressibility and shear characteristics of Radforth peats. In In STP 820, P.M. Jarrett (STP 820, P.M. Jarrett (EdEd.), ASTM .), ASTM

Committee D-18 Symposium, Toronto, Canada, pp. 157-191. Committee D-18 Symposium, Toronto, Canada, pp. 157-191. Landva, A.O., Korpijaakko, E.O. and Pheeney, P.E. 1986. Notes on the original von Post peat and peatland classification system. Proc. Landva, A.O., Korpijaakko, E.O. and Pheeney, P.E. 1986. Notes on the original von Post peat and peatland classification system. Proc.

Advances in Peatlands Engineering, Carleton University, Ottawa, pp.16-29. Advances in Peatlands Engineering, Carleton University, Ottawa, pp.16-29. Landva, A.O., Pheeney, P.E., La Rochelle, P. and Briaud, J.-L. 1986. Structures on peatland – geotechnical investigations. Proc. Advances Landva, A.O., Pheeney, P.E., La Rochelle, P. and Briaud, J.-L. 1986. Structures on peatland – geotechnical investigations. Proc. Advances

in Peatlands Engineering, Carleton University, pp.31-52.in Peatlands Engineering, Carleton University, pp.31-52.

BIBLIOGRAPHYBIBLIOGRAPHY Landva, A.O., Clark, J.I., Crooks, J.H.A. and Burwash, W.J. 1986. Degradation of peats and organic soils under engineered structures – a Landva, A.O., Clark, J.I., Crooks, J.H.A. and Burwash, W.J. 1986. Degradation of peats and organic soils under engineered structures – a

preliminary study. Proc. Advances in Peatlands Engineering, Carleton University, pp.109-115.preliminary study. Proc. Advances in Peatlands Engineering, Carleton University, pp.109-115. Landva, A.O., Valsangkar, A.J. and Charalambous, P. 1988. Performance of a raft foundation supporting a multi storey structure. Can. Landva, A.O., Valsangkar, A.J. and Charalambous, P. 1988. Performance of a raft foundation supporting a multi storey structure. Can.

Geot. Journal, vol. 25, No. 1.Geot. Journal, vol. 25, No. 1. Landva, A.O., Valsangkar, A.J. and Wroblevicz, Z. 1994. Long-term performance of raft and footing foundations above clayey silt. ASCE Landva, A.O., Valsangkar, A.J. and Wroblevicz, Z. 1994. Long-term performance of raft and footing foundations above clayey silt. ASCE

Spec. Geot. Publ. No. 40, Settlement 1994 Conference, vol. 1. Texas A & M. University, pp. 860-874.Spec. Geot. Publ. No. 40, Settlement 1994 Conference, vol. 1. Texas A & M. University, pp. 860-874. Landva, A.O. 2007. Characterization of Escuminac peat and construction on peatland. Landva, A.O. 2007. Characterization of Escuminac peat and construction on peatland. In In Characterization and Engineering Properties of Characterization and Engineering Properties of

Natural Soils. Natural Soils. Edited byEdited by T.S Tan, K.K. Phoon, D.W. Hight and S. Leroueil. Taylor and Francis Group, London, pp. 2135-2189. T.S Tan, K.K. Phoon, D.W. Hight and S. Leroueil. Taylor and Francis Group, London, pp. 2135-2189. Larsson, R. 1990. Behaviour of organic clay and gyttja. Swed. Geot. Inst. Report No. 38, Linköping, Sweden.Larsson, R. 1990. Behaviour of organic clay and gyttja. Swed. Geot. Inst. Report No. 38, Linköping, Sweden. Lea, N.D. and Brawner, C.O. 1963. Highway design and construction over peat deposits in lower British Columbia. Highway Res. Bd., Rec. Lea, N.D. and Brawner, C.O. 1963. Highway design and construction over peat deposits in lower British Columbia. Highway Res. Bd., Rec.

7: 1-33 Washington, DC.7: 1-33 Washington, DC. Lefebvre, G., Langlois, P., Lupien, C. and Lavallée, J.-G. 1984. Laboratory testing and in situ behaviour of peat as embankment Lefebvre, G., Langlois, P., Lupien, C. and Lavallée, J.-G. 1984. Laboratory testing and in situ behaviour of peat as embankment

foundation. Can. Geot. Journal, vol. 21, No. 2.foundation. Can. Geot. Journal, vol. 21, No. 2. Lo, K.Y. 1962. Shear strength properties of a sample of volcanic material of the Valley of Mexico. Géotechnique 12.Lo, K.Y. 1962. Shear strength properties of a sample of volcanic material of the Valley of Mexico. Géotechnique 12. Lupien, C., Lefebvre, G., Rosenberg, P. and Lavallée, J.G. 1981. Observations during construction of till embankments on peat Lupien, C., Lefebvre, G., Rosenberg, P. and Lavallée, J.G. 1981. Observations during construction of till embankments on peat

foundation. Proc. 34th Can. Geot. Conf., Fredericton, NB. foundation. Proc. 34th Can. Geot. Conf., Fredericton, NB. Lupien, C., Lefebvre, G., Rosenberg, P., Paré, J.J. and Lavallée, J.G. 1983. The use of fabrics for improving the placement of till on peat Lupien, C., Lefebvre, G., Rosenberg, P., Paré, J.J. and Lavallée, J.G. 1983. The use of fabrics for improving the placement of till on peat

foundation. 62nd Annual Meeting of the Transportation Research Board, Washington, DC.foundation. 62nd Annual Meeting of the Transportation Research Board, Washington, DC. MacKenzie, W.B. 1902. Notes on railway work. Lecture given to the Engineering Society of the University of New Brunswick, October MacKenzie, W.B. 1902. Notes on railway work. Lecture given to the Engineering Society of the University of New Brunswick, October

1902. Constitution and Lectures 1902-1904.1902. Constitution and Lectures 1902-1904. MacFarlane, I.C. and Rutka, A. 1961. An evaluation of pavement performance over muskeg in Northern Ontario. Highway Research MacFarlane, I.C. and Rutka, A. 1961. An evaluation of pavement performance over muskeg in Northern Ontario. Highway Research

Board Bulletin 316, Washington, DC.Board Bulletin 316, Washington, DC. Magnan, J.P. 1980. Classification géotechnique des sols: 1 – A propos de la classification LPC. Bulletin de liaison des Laboratoires des Magnan, J.P. 1980. Classification géotechnique des sols: 1 – A propos de la classification LPC. Bulletin de liaison des Laboratoires des

Ponts et Chaussées, Paris, 105: 49-52.Ponts et Chaussées, Paris, 105: 49-52. Mesri, G. 1975. Discussion on ‘New design procedure for stability of soft clays’. J. Geotech. Div., ASCE, Reston, VA. 101(4): 409-412.Mesri, G. 1975. Discussion on ‘New design procedure for stability of soft clays’. J. Geotech. Div., ASCE, Reston, VA. 101(4): 409-412. Mesri, G., Rokhsar, A. and Bohor, B.F. 1975. Composition and compressibility of typical samples of Mexico City clay. Géotechnique 25, Mesri, G., Rokhsar, A. and Bohor, B.F. 1975. Composition and compressibility of typical samples of Mexico City clay. Géotechnique 25,

No. 3, p. 527. No. 3, p. 527. Mesri, G. and Ajlouni, M. 2007. Engineering properties of fibrous peats. J. Geot. and Geoenv. Eng., vol. 133, No. 7, pp. 850-866.Mesri, G. and Ajlouni, M. 2007. Engineering properties of fibrous peats. J. Geot. and Geoenv. Eng., vol. 133, No. 7, pp. 850-866. Miyakawa, I. 1960. Some aspects of road construction in peaty or marshy areas in Hokkaido, with particular reference to filling methods. Miyakawa, I. 1960. Some aspects of road construction in peaty or marshy areas in Hokkaido, with particular reference to filling methods.

Civil Eng. Research Inst., Hokkaido Development Bureau, Sapporo.Civil Eng. Research Inst., Hokkaido Development Bureau, Sapporo.

BIBLIOGRAPHYBIBLIOGRAPHY Mullins, B. and Mullins, M.B. 1848. On the origin and reclamation of peat bog, with some observations on the construction of roads, railways Mullins, B. and Mullins, M.B. 1848. On the origin and reclamation of peat bog, with some observations on the construction of roads, railways

and canals in bog. Trans. Inst. of Civil Eng. of Ireland, vol. II, pp. 1-48 + plates I-V. Presented to the Institution on February 10th, 1846.and canals in bog. Trans. Inst. of Civil Eng. of Ireland, vol. II, pp. 1-48 + plates I-V. Presented to the Institution on February 10th, 1846. Muskeg Engineering Handbook 1969. Muskeg Subcommittee of the NRC Associate Committee on Geotechnical Research. Muskeg Engineering Handbook 1969. Muskeg Subcommittee of the NRC Associate Committee on Geotechnical Research. Edited by Edited by I.C. I.C.

MacFarlane. University of Toronto Press, 297 pp.MacFarlane. University of Toronto Press, 297 pp. Nichol, D. 1998. Construction over peat in Greater Vancouver, British Columbia. Proc. Inst. of Civil Eng.: Municipal Engineer, 127: 109-119.Nichol, D. 1998. Construction over peat in Greater Vancouver, British Columbia. Proc. Inst. of Civil Eng.: Municipal Engineer, 127: 109-119. Perrin, J. 1974. Classification des sols organiques. Bulletin de liaison des Laboratoires des Ponts et Chaussées, Paris, 69: 39-47. Perrin, J. 1974. Classification des sols organiques. Bulletin de liaison des Laboratoires des Ponts et Chaussées, Paris, 69: 39-47. Pheeney, P.E. 1976. Fabric and geotechnical behaviour of sphagnum peats. M.Sc.Eng. thesis, Department of Civil Engineering, University Pheeney, P.E. 1976. Fabric and geotechnical behaviour of sphagnum peats. M.Sc.Eng. thesis, Department of Civil Engineering, University

of New Brunswick.of New Brunswick. Radforth, N.W. 1969. Muskeg as an engineering problem. Radforth, N.W. 1969. Muskeg as an engineering problem. InIn Muskeg Engineering Handbook, University of Toronto Press. Muskeg Engineering Handbook, University of Toronto Press. Ed. Ed. I.C. I.C.

MacFarlane.MacFarlane. Ripley, C.F. and Leonoff, C.E. 1961. Embankment settlement behaviour on deep peat. Proc. 7th Muskeg Res. Conf., NRC of Canada, Ripley, C.F. and Leonoff, C.E. 1961. Embankment settlement behaviour on deep peat. Proc. 7th Muskeg Res. Conf., NRC of Canada,

Assoc. Ctee. on Soil and Snow Mech., Tech. Mem. 71.Assoc. Ctee. on Soil and Snow Mech., Tech. Mem. 71. Reid, A.G. 1967. Construction over peat. Vancouver Soils Group, Peat Symposium February 1967. Reid, A.G. 1967. Construction over peat. Vancouver Soils Group, Peat Symposium February 1967. Root, A.W. 1958. California experience in construction of highway across marsh deposits. Highwau Research Board, Bull. 173, Washington, Root, A.W. 1958. California experience in construction of highway across marsh deposits. Highwau Research Board, Bull. 173, Washington,

DC.DC. Rowe, R.K. 1984. Recommendations for the use of geotextile reinforcement in the design of low embankments on very soft/weak soils. In Rowe, R.K. 1984. Recommendations for the use of geotextile reinforcement in the design of low embankments on very soft/weak soils. In

Geotextiles in Filtration & Drainage, Geotextiles in Filtration & Drainage, Corbet, S. and King, J. (Corbet, S. and King, J. (EdsEds.), Thomas Telford, London, England, pp. 1-12. .), Thomas Telford, London, England, pp. 1-12. Rowe, R.K., MacLean, M.D. and Barsvary, A.K. 1984. The observed behaviour of a geotextile-reinforced embankment constructed on peat. Rowe, R.K., MacLean, M.D. and Barsvary, A.K. 1984. The observed behaviour of a geotextile-reinforced embankment constructed on peat.

Can. Geot. J., 21, 2.Can. Geot. J., 21, 2. Rowe, R.K., MacLean, M.D. and Soderman, K.L. 1984. Analysis of a geotextile-reinforced embankment constructed on peat. Can. Geot. J., Rowe, R.K., MacLean, M.D. and Soderman, K.L. 1984. Analysis of a geotextile-reinforced embankment constructed on peat. Can. Geot. J.,

21, 3.21, 3. Rowe, R.K. and Soderman, K.L. 1985a. An approximate method for estimating the stability of geotextile-reinforced embankments. Can. Rowe, R.K. and Soderman, K.L. 1985a. An approximate method for estimating the stability of geotextile-reinforced embankments. Can.

Geot. J., 22, 3.Geot. J., 22, 3. Rowe, R.K. and Soderman, K.L. 1985b. Reinforced embankments on very poor foundations. Geotextiles and Geomembranes, 4: 65-81.Rowe, R.K. and Soderman, K.L. 1985b. Reinforced embankments on very poor foundations. Geotextiles and Geomembranes, 4: 65-81. Rowe, R.K. and Soderman, K.L. 1986. Reinforced embankments on very poor foundations. Geotextiles and Geomembranes, 2: 277-298.Rowe, R.K. and Soderman, K.L. 1986. Reinforced embankments on very poor foundations. Geotextiles and Geomembranes, 2: 277-298. Rowe, R.K. and Mylleville, B.L.J. 1996. A geogrid reinforced embankment on peat over organic silt: a case history. Can. Geot. J., 33, 1.Rowe, R.K. and Mylleville, B.L.J. 1996. A geogrid reinforced embankment on peat over organic silt: a case history. Can. Geot. J., 33, 1. Rowe, R.K. (Rowe, R.K. (ed.ed.) 2001. ) 2001. Geotechnical and Geoenvironmental Engineering HandbookGeotechnical and Geoenvironmental Engineering Handbook. Kluwer Academic Publishers, Boston, 1088 pp.. Kluwer Academic Publishers, Boston, 1088 pp. Rowe, R.K., Gnanendran, C.T., Valsangkar, A.J. and Landva, A.O. 2001. Performance of a test embankment constructed on an organic Rowe, R.K., Gnanendran, C.T., Valsangkar, A.J. and Landva, A.O. 2001. Performance of a test embankment constructed on an organic

clayey silt deposit. Can. Geot. J., 38, 1283-1296.clayey silt deposit. Can. Geot. J., 38, 1283-1296.

BIBLIOGRAPHYBIBLIOGRAPHY Royer, J.A. 1936. Experimental road for heavy traffic on a very compressible soil (peat bog ground). Proc. 1st Int. Conf SMFE, vol. I.Royer, J.A. 1936. Experimental road for heavy traffic on a very compressible soil (peat bog ground). Proc. 1st Int. Conf SMFE, vol. I. Samson, L. and La Rochelle, P. 1971. Design and performance of an expressway constructed over peat by preloading. Can. Geot. J., Samson, L. and La Rochelle, P. 1971. Design and performance of an expressway constructed over peat by preloading. Can. Geot. J.,

9, 4.9, 4. Samson, L. 1985. Postconstruction settlement of an expressway built on peat by precompression. Can. Geot. J., 22, 3.Samson, L. 1985. Postconstruction settlement of an expressway built on peat by precompression. Can. Geot. J., 22, 3. Scotton, S. 1981. Experiences with organic soils in the Greater Vancouver area of south-western British Columbia. Proc. 34th Can. Scotton, S. 1981. Experiences with organic soils in the Greater Vancouver area of south-western British Columbia. Proc. 34th Can.

Geot. Conf., Fredericton, NB.Geot. Conf., Fredericton, NB. Silburn, J.D. 1972. Peat as the impermeable membrane in an earth dam. Symp. on Peat Moss in Canada, Univ. of Sherbrooke.Silburn, J.D. 1972. Peat as the impermeable membrane in an earth dam. Symp. on Peat Moss in Canada, Univ. of Sherbrooke. Skempton, A.W. 1957. Skempton, A.W. 1957. Discussion: Discussion: The planning and design of the new Hong Kong airport. Proc. Inst. Civil Engrs., London, 7, pp. The planning and design of the new Hong Kong airport. Proc. Inst. Civil Engrs., London, 7, pp.

305-307.305-307. Spence, R.A. 1967. Consolidation of fibrous peat. Vancouver Soils Group, Peat Symposium February 1967.Spence, R.A. 1967. Consolidation of fibrous peat. Vancouver Soils Group, Peat Symposium February 1967. Tavenas, F.A. and Leroueil, S. 1987. State-of-the-art on laboratory and in-situ stress-strain-time behaviour of soft clays. Tavenas, F.A. and Leroueil, S. 1987. State-of-the-art on laboratory and in-situ stress-strain-time behaviour of soft clays. InIn Proc. Int. Proc. Int.

Symp. on Geot. Eng. of Soft Soils, Mexico City, pp. 1-46.Symp. on Geot. Eng. of Soft Soils, Mexico City, pp. 1-46. Terzaghi, K. 1946. Report concerning the subsoil conditions at the site of the proposed flying field at Väsby. Terzaghi, K. 1946. Report concerning the subsoil conditions at the site of the proposed flying field at Väsby. Appendix I Appendix I in Swedish in Swedish

Geot. Inst. Report No. 13, Linköping 1981.Geot. Inst. Report No. 13, Linköping 1981. Terzaghi, K. and Peck, R.B. 1967. Soil mechanics in engineering practice. 2nd ed., Wiley, New York.Terzaghi, K. and Peck, R.B. 1967. Soil mechanics in engineering practice. 2nd ed., Wiley, New York. Tresidder, J.O. 1958. A review of existing methods of road construction over peat. Dept. of Scientific and Industrial Research. Road Tresidder, J.O. 1958. A review of existing methods of road construction over peat. Dept. of Scientific and Industrial Research. Road

Res. Tech. Paper No. 40, London. Her Majesty’s Stationery Office.Res. Tech. Paper No. 40, London. Her Majesty’s Stationery Office. UNB 1997. Microscopy and Microanalysis Facility, UNB Campus, Fredericton, NB.UNB 1997. Microscopy and Microanalysis Facility, UNB Campus, Fredericton, NB. van der Burght, J.H. 1936. Long duration consolidation tests. 1st Int. Conf. SMFE, vol. 1, p.51, Cambridge, Mass.van der Burght, J.H. 1936. Long duration consolidation tests. 1st Int. Conf. SMFE, vol. 1, p.51, Cambridge, Mass. Vidal, H. 1969. The principle of reinforced earth. Hwy. Res. Rec. No. 282, Highway Res. Board, National Academy of Sciences, NRC, Vidal, H. 1969. The principle of reinforced earth. Hwy. Res. Rec. No. 282, Highway Res. Board, National Academy of Sciences, NRC,

National Academy of Engineering. National Academy of Engineering. von Post L. 1922. Sveriges Geologiska Undersöknings torvinventering och nogra av dess hittils vunna resultat (SGU’s peat inventory von Post L. 1922. Sveriges Geologiska Undersöknings torvinventering och nogra av dess hittils vunna resultat (SGU’s peat inventory

and some preliminary results). Svenska Mosskulturföreningens Tidsskrift (J. Swedish Moss Culture Society), vol. 36, Jönköping, and some preliminary results). Svenska Mosskulturföreningens Tidsskrift (J. Swedish Moss Culture Society), vol. 36, Jönköping, Sweden. Sweden.

Warnock, T.A. 1967. Construction of roads on peat foundations using lightweight rafts. J. Inst. of Highway Engineers, vol. 14, (4). Warnock, T.A. 1967. Construction of roads on peat foundations using lightweight rafts. J. Inst. of Highway Engineers, vol. 14, (4). Weber, W.G. 1969. Performance of embankments constructed over peat. Proc. Amer. Soc. of Civil Engr., J. SMFE, vol. 95, SM1.Weber, W.G. 1969. Performance of embankments constructed over peat. Proc. Amer. Soc. of Civil Engr., J. SMFE, vol. 95, SM1. Wiesner, W.R. and Hardy, R.M. 1978. Design and construction experiences with fluid retaining embankments on peat. Proc. 17th Wiesner, W.R. and Hardy, R.M. 1978. Design and construction experiences with fluid retaining embankments on peat. Proc. 17th

Muskeg Res. Conf., NRC of Canada, Tech. Memo. 122.Muskeg Res. Conf., NRC of Canada, Tech. Memo. 122.

TOTAL LAND AREAIN CANADA

Peatland area

Forested area where surface organics dominateForested area

45% 12.5%

8.5%

- Total land area in Canada 1,000,000,000 ha- 660,000,000 ha or 2/3 of the total land area is

peatland and forestry country: "an enormous area" (1975 Muskeg Research Conference) Other

34%

PEAT originates from plants and denotes the various stages in the humification process where the plant structure can still be discerned. Peat is a sedentary soil which has been formed in situ from the original material.

DY, which has a somewhat sticky consistency and is generally brown-black in colour, denotes the various stages in the humification process where the plant structure is completely destroyed. Some types of dy are formed in situ, where they constitute the highest degree of humification of the peat. Other types of dy have been transported by water and precipitated in a colloidal form in environments with low contents of calcium.

GYTTJA, which has a more or less elastic consistency and is generally greenish in colour, originates from remains of plants and animals rich in fats and proteins, in contrast to peat which is formed from remains of plants rich in carbohydrates. Dead microscopic aquatic animals are dissolved and decomposed with the aid of bacteria to a flocculent substance, in which mineral particles and less decomposed remains of plants and animals are embedded. Further decomposition occurs with the aid of organisms living in the substance, such as worms and larvae. Fermentation processes generating sulphuretted hydrogen and methane complete the formation of gyttja.

BEHAVIOUR OF ORGANIC CLAY AND GYTTJA BEHAVIOUR OF ORGANIC CLAY AND GYTTJA (Larsson 1990)(Larsson 1990)

“RAILWAY ON PEAT BOGS OR SWAMPS:Should your line cross a morass, peat-bog or swamp,(1) Drain and side ditch where possible, and thus make bog

firm enough to carry, in preference to cross logging. Ditches may be 5 feet deep, and, if possible, 20 to 50 feet from the centre line.

(2) Do not cross-log where bank is high and settlement likely to be considerable, only where bog is nearly but not quite sufficient to sustain the bank. The cross-logs broaden the base and form a light material for part of the bank; used in any other way, they are more harm than good.

(3) Keep grade low.(4) Make banks as light as possible, using turf, peat, sawdust

or cinders.(5) If sides bulge up much, leave only 5 ft. berm* between

toe of bank and edge of ditch; but, if no bulging, make berm as wide as possible.”

*= space“In places where piles are not desirable, the ground may be consolidated in the following manner: Prepare a piece of hard wood 4 in. diameter 6 feet long, pointed at one end, and having an iron ring on the other end. Drive this down about five feet with a hand maul, pull it out again with a lever and chain, pour sand or gravel into the hole and pack it down with an iron bar. Begin at the outside and work towards the centre, putting the holes about 18 inches apart. By the time you reach the centre, the ground will be almost as hard as rock. I have used this very successfully under bridge abutments and turn-table centres. In Paris, the ground under the Exhibition Buildings was consolidated in this manner, though on a larger scale. There, a cone-shaped casting or punch was used which weighed 2,000 lbs. This was exactly like the hammer of a pile-driver, being allowed to fall from the top of a pair of leaders about 20 feet high. The punch, on falling, buried itself in the soft ground, and was pulled out by the wire rope attached to the drum of the engine. Sand or gravel was then shovelled into the hole and the punch allowed to fall again into the same hole; and so on until the hole was filled. The leaders were then moved 4 or 5 feet away, and the same thing repeated until the whole area was consolidated – in some cases to a depth fifteen feet below the surface. Two shapes of punches were used. A testing hammer, was also first used to test the carrying capacity of the natural ground, so that the degree of additional consolidation required might be estimated.”

107 YEARS AGO LITTLE N.B. 107 YEARS AGO LITTLE N.B. WAS A PIONEER ! (WAS A PIONEER ! (Notes on Notes on

Railway Work by Wm. B. MacKenzie, C.E. Railway Work by Wm. B. MacKenzie, C.E.

250 mm250 mm

50 mm 50 mm

25 mm 10 mm

Comparison betweenComparison betweenfilter paper and filter paper and sphagnum peat sphagnum peat leavesleaves

(a) Whatman filter (a) Whatman filter paper (65X)paper (65X)(b) Ditto (330X) (b) Ditto (330X) (c) Ditto (600X)(c) Ditto (600X)(d) SH(d) SH11 leaves (65X) leaves (65X)(e) SH(e) SH33 leaf (330X) leaf (330X)(f) SH(f) SH11 leaf (1600X) leaf (1600X)

SETTLEMENT OF DIKES ON PEAT FROM SETTLEMENT OF DIKES ON PEAT FROM 1840-1930 (van der Burght 1936)1840-1930 (van der Burght 1936)

Marken

Amsterdam

Ysselmeer

NOORDZEE

0 50 100 KM

0 10M

Ysselmeer

CLAYPEATSAND

N.A.P.

1.00+

1.20+

1.40+

1.00+

1.60+

1.00+

1.20+

1.40+

1.60+

1.00+

1.20+

1.60+

1.00+

1.20+

1850 1860 1870 18801890

1900 1910 1920 19301840

SETTLEMENT OF SETTLEMENT OF DIKES ON PEAT, DIKES ON PEAT,

1840-1930 (van der 1840-1930 (van der Burght 1936, Burght 1936,

Buisman 1936)Buisman 1936)

Initial load (1841)Δp = 33 kPa

Maximum load (1924)S = 1.67 m (1841-1924)Δp = 45 kPa

0

20

40

60

80

100

120

140

160

180

200

10 100YEARS

SE

TT

LE

ME

NT

(c

m)

Failure?

Failure?

140

120

100

80

60

40

20

01 10 100 1000

0

1

2

3

4

5

6

PR

ES

SU

RE

(k

Pa

)

BE

RM

HE

IGH

T (

m)

TIME (days)

Berm Height

MIRAMICHI WASTEWATER TREATMENT BERM ON MIRAMICHI WASTEWATER TREATMENT BERM ON ORGANIC DIATOMACEOUS SILT (1997) ORGANIC DIATOMACEOUS SILT (1997)

0

-50

-100

-150

-200

-250

-300

-3501 10 100 1000

0

1

2

3

4

5

6

SE

TT

LE

ME

NT

(m

m)

BE

RM

HE

IGH

T (

m)

TIME (days)

Berm Height

MIRAMICHI WASTEWATER TREATMENT BERM ON MIRAMICHI WASTEWATER TREATMENT BERM ON ORGANIC DIATOMACEOUS SILT (1997) ORGANIC DIATOMACEOUS SILT (1997)

Time

Secondary Time Effect

Settlement

0.8 S1 (+)

Un

it L

oad q

tn

0

(A)

VVÄÄSBY TEST FILL SBY TEST FILL GENERAL THEORY OF CONSOLIDATIONGENERAL THEORY OF CONSOLIDATION

(Terzaghi 1946)(Terzaghi 1946)

Time

Secondary Time Effect

Settlement

0.8 S1 (+)

Un

it L

oad q

tn

0

(A)

Time

Un

it L

oad

Settlement

t1

C2

C1

S2

S1

0.75S1

q1 q2=2/3q1

(B)

VVÄÄSBY TEST FILL SBY TEST FILL PRIMARY CONSOLIDATION PRIMARY CONSOLIDATION

UNDER SURCHARGE qUNDER SURCHARGE q11 AND AND UNDER PERMANENT FILL qUNDER PERMANENT FILL q22

(Terzaghi 1946)(Terzaghi 1946)

Time

Secondary Time Effect

Settlement

0.8 S1 (+)

Un

it L

oad q

tn

0

(A)

Time

Un

it L

oad

Settlement

t1

C2

C1

S2

S1

0.75S1

q1 q2=2/3q1

(B)

VVÄÄSBY TEST FILL – PRIMARY AND SECONDARY SBY TEST FILL – PRIMARY AND SECONDARY CONSOLIDATION UNDER SURCHARGE (Terzaghi CONSOLIDATION UNDER SURCHARGE (Terzaghi

1946) 1946)

Un

it L

oad

Settlement

t1 t2

C2

C2

C1

S2

S1

0.75S1?

q1 q2=2/3q1

(C)

SURCHARGE ON PEAT (Brawner 1969)SURCHARGE ON PEAT (Brawner 1969)1 10 100 100 10000

3.5 FT

4.3 FT

Total Settlement under 6' fill after 25 yrsSurcharge can be removed when settlement reaches or exceeds 2.8 feet

DAYS

SE

TT

LEM

EN

T,

FE

ET

0

1.0

2.0

3.0

4.0

5.0

6.0

6 ft Fill11 ft Fill11 ft fill for 28 days, then 5 ft removed

11 ft fill for 28 days, then 5 ft removed (prop.)

B

C

D

G

E

A

0.01 0.1 1.0LOAD (TONS / SQ.FT.)

1

2

3

4

5

6

7

8

9

10

SE

TT

LE

ME

NT

(F

EE

T)

10

3 month duration of load25 year duration of load

TIME-SETTLEMENT TIME-SETTLEMENT CURVES CURVES ILLUSTRATING ILLUSTRATING PRECONSOLIDATIOPRECONSOLIDATION PRINCIPLEN PRINCIPLE

CHART CHART ILLUSTRATING ILLUSTRATING PROCEDURE USED PROCEDURE USED TO DETERMINE TO DETERMINE PRECONSOLIDATIOPRECONSOLIDATION SURCHARGE N SURCHARGE LOADLOAD

DIRECT SIMPLE SHEAR, SHDIRECT SIMPLE SHEAR, SH33 PEAT PEATVERTICAL CONSOLIDATION STRESS = 20 kPaVERTICAL CONSOLIDATION STRESS = 20 kPaLATERAL CONSOLIDATION STRESS LATERAL CONSOLIDATION STRESS ≈≈ 8 kPa 8 kPa

2010 30 40

10

20

1

H

Τ (

kPa)

σ (kPa)

σv

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

STAGE 1-2, PURE SHEARSTAGE 1-2, PURE SHEARFAILURE PLANE FP 1-2FAILURE PLANE FP 1-2

2010 30 40

10

20

FP1-2

1

2

0 5 10 15 20 25

10

20

PP2

PP1

1

2

PP = POLE POINT

H

c=2.5 kPa, Ф=30o

Τ (

kPa)

Τ (

kPa)

ε (%)

εs = δh

Hσv

δh Τ

σ (kPa)

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

STAGE 2-3, END OF PURE SHEARSTAGE 2-3, END OF PURE SHEARFAILURE PLANE FP 2-3FAILURE PLANE FP 2-3

2010 30 40

10

20FP2-3

FP1-2

1

2

3

0 5 10 15 20 25

10

20

PP2

PP1

PP3

1

23

Τ (

kPa)

σ (kPa)

σv

Τ

Τ (

kPa)

ε (%)

c=2.5 kPa, Ф=30o

c=4.7 kPa, Ф=30o

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

STAGE 3-4STAGE 3-4FAILURE PLANE FP 3-4FAILURE PLANE FP 3-4

2010 30 40

10

20 FP3-4

1

4

0 5 10 15 20 25

10

20

PP4

1

43

2

Τ (

kPa)

σ (kPa)

σv

Τ

Τ (

kPa)

ε (%)

c=6.0 kPa, Ф=30o

c=2.5 kPa, Ф=30o

DIRECT SIMPLE SHEAR DIRECT SIMPLE SHEAR , SH, SH33 PEAT PEAT

FINAL STAGE 4-5FINAL STAGE 4-5FAILURE PLANE FP 4-5 (horizontal)FAILURE PLANE FP 4-5 (horizontal)

2010 30 40

10

20

FP4-5

5

0 5 10 15 20 25

10

20

1

PP5

1

4

3

2

5

Τ (

kPa)

σ (kPa)

Τ (

kPa)

ε (%)

σv

Τ

c=2.5 kPa, Ф=30o

DESIGN CHART FOR PEAT UNDERLAIN DESIGN CHART FOR PEAT UNDERLAIN BY A FIRM BASE (after Rowe & BY A FIRM BASE (after Rowe &

Soderman 1985)Soderman 1985)

TF = test fills at TF = test fills at Escuminac (peat Escuminac (peat thickness 7.4m, thickness 7.4m,

w=1200 to w=1200 to 1800%)1800%)

10

20

30

40

0 500 1000 1500 2000

Depth

D=3m

5m8m7.4m

h(kPa)

Geosynthetic Tensile Stiffness J (kN/m)

TF3

TF9

TF6a

Bm = 0.34

h = Height of Embankment Above Original Ground Level (h=H-Sr)

= Unit Weight of Fillgf

gf