construction roads and highways on peat -...

CONSTRUCTION ROADS

AND HIGHWAYS ON PEAT

Dr. C. T. Toh, Ir. Chee Sai Kim

DR. C.T. TOH CONSULTANT

ACKNOWLEDGEMENT

The authors are indebted to the following for the opportunities to develop the methods of peat treatment over the last 18 years:

• Pakatan Runding Yusof (PRY)

• Jurutera MINSAR

• Konsultant SHC

• Konsortium Malaysia

• Jurutera Perunding WAHBA

• Ireka Engineering and Construction Sdn Bhd

• Perunding E C Sepakat

• Sibu Municipal Council

• PLB

• DIRD Pty Ltd (Dacca)

LECTURE TOPICS

• Occurrence and distribution

• Types and classifications

• Properties

• Soil Investigations

• Stability

• Settlement

• Methods of placing fills

• Case histories

• Decomposition’

• Role of peat swamps in Global warming

DISTRIBUTION OF PEAT and

PEATY ORGANIC SOILS

PENINSULAR MALAYSIA

• Near KLIA airport – about 4 m deep peat.

• Air Itam – Kulai, Johore – 4 to 7 m deep peat

but can be as deep as 12 m in isolated areas

• Putra Jaya – organic soils can extend to 15 m

• Trengganu – as deep as 4 to 5 m with soft clay

beneath

• Batang Berjuntai

SOIL MAP JOHORE

SARAWAK

SIGNIFICANT EXTENT OF PEAT

Some Examples• SIBU TOWN – KNOWN TO BE AS DEEP AS 17 M

• BATU KAWA – 3 TO 6 M OVER SOFT CLAY OR LIMESTONE

• PETRA JAYA – UP TO 7 M WITH SOFT CLAY BENEATH

• BALINGIAN – UP TO ABOUT 6 M WITH SOFT CLAY BENEATH

• MATANG –UP TO ABOUT 5 M WITH SOFT CLAY BENEATH’

• LIMBANG AREA

• MIRI – BEHIND CANADA HILL

PEAT MAP OF SARAWAK

WORLD PEAT DISTRIBUTION

13,000 sq kmPoland

14,000 sq kmUganda

14,000 sq kmIreland

Brazil

Germany

Malaysia

Norway

China

Sweden

Finland

Indonesia

USA

USSR

Canada

15,000 sq km

16,000 sq km

25,000 sq km

30,000 sq km

42,000 sq km

70,000 sq km

100,000 sq km

170,000 sq km

600,000 sq km

1,500,000sq km

1,500,000sq km

10%

20%

34%

14%

10%

18%

World wide peat distribution

1 to 99%15 other

countries

10%Scotland

220 to 10,000

sq km

26 other

countries

11,000 sq kmZambia

11,000 sq kmChile

12,000 sq kmFalklands

PEAT . FORMS

Two forms that characterize the deposition of

peat:

• Valley peat which are flat and layered with river

deposits;

• Basin peat which forms domes that can be up to

15 m high –also reported in Ireland and UK

• In Peninsular Malaysia the peat appears to be

valley peat whereas both forms of peat are

found in Sarawak.

Fig. 5. I a11ning lectTon micropJ1 t graph of l1orizontal ection ~of

Jan1 Ba peat h~owing fabric with v r ' larg m ~ cro~p r s

GEOLOGICAL FORMATION

MODEL

for

BATANG RAJANG PEAT

from Lam Sia Keng

(A) Ro1pid denudation ·Ond deep incis io~n of Tertiary country rocks during Late Pleistocene.

surface b-erore active denudation

-- - tidal floo"Cflevel

(B) Deposition of sediments by Satang Rajang forming de'ltcs and flo.odp~o ins during Hol,ocene.

LEGEND UiliiJJ Tertiary country rocks ~'! ... ~ ~~: Floodplain depoaita :-: ... :-: Organic and miMrcl {?:"' ·:j Orq~nk: depoa•ts - (sand, s~t. clay) 10-...;;;.~ deposita (ombrogenQuS pact)

(clayey peort /pecty cia~ or topogeneoua paat)

(C) Accumal·ation of organic ·end minera:l deposits (p·eaty clay / claye:y p·eat) in basins betweer

!levees end isoll ~ated hills.

(D) Accumulation of organic m,att.ers only (ombrogenous pect) in bas'ins above tidal floodlev~el· J p to prese~nt.

&fang Ra}Dng

l·evee

tidal floodl,eve I

fj::::::~Organic ~and mi·neral F:_ .. >I Organic depoaibs deposits ( ombrogenous pe (clayey peat/peaty clay or topogeneoua pe,at)

PEAT CLASSIFICATION

PEAT MAIN TYPES

Peat is derived from plants and can be very fibrous. As the degree of humification# increases, the peat becomes less and less fibrous until it is transformed into an amorphous* mass without any discernable structures.

# Convert plant remains to humus

* Without a clearly defined shape

IMPORTANT BASIC PROPERTIES FOR

PEAT CLASSIFICATION

• Natural moisture content (%)

• Ash content (%) = 100 – Organic content

• Ignition loss (%) close to the value of the

organic content.

When peat burnt organic content becomes

CO2, the ash left is reflective of soil

content.

w, kg/kg

'" -

13 12 II I

- I

10 ' 9 8' 7 ' 6

0

s~----~----~----~~--~~--.10 20 JO t,O SO Ddec 0/o

Fig. 2: Water content vs. degree of decomposition. ( 1) bog peat, (2) transition peat, (3) fen peat. From Amaryan (1993).

PEAT CLASSIFICATION

Von Post System

(Best known –more for agricultural

purposes

Based on botanical components, degree

of humification, water content, fine and

coarse fibre content.

10 grades H1 to H10.

Von Post System

Slightly decomposed peat which releases very muddy dark

water. No peat passes between fingers but the plant

remains are slightly pasty and have lost some of the

identifiable features.

H4

Very slightly decomposed peat which releases very muddy

brown water but for which no peat passed between fingers.

Plant remains still identifiable and no amorphous material

present.

H3

Almost completely un-decomposed peat which releases

clear or yellowish water. Plant remains easily identifiable.

No amorphous material present.

H2

Completely un-decomposed. Releases clear water. Plant

remains easily identifiable. No amorphous material present.H1

Von Post System

Strongly decomposed peat. Contains a lot of amorphous

material with very faintly recognizable plant structure.

When squeezed about 1/2 of the peat escapes between

fingers. The water, if any released, is very dark and

almost pasty.

H7

Moderately strongly decomposed peat with a very

indistinct plant structure. When squeezed, about 1/3 of

the peat escapes between the fingers. The residue is

strongly pasty but shows the plant structure more

distinctly than before squeezing.

H6

Moderately decomposed peat which releases very

muddy water with also a very small amount of

amorphous granular peat escaping between fingers. The

structure of plant remains is quite indistinct, although it is

still possible to identify certain features. The residue is

strongly pasty.

H5

Von Post System

Completely decomposed peat with no discernable

plant structure. When squeezed all the wet peat

escapes between the fingers.

H10

Practically fully decomposed peat in which there is

hardly any recognizable plant structure. When

squeezed almost all of the peat escapes between

fingers as a fairly uniform paste.

H9

Very strongly decomposed peat with a large quantity

of amorphous material and very dry indistinct plant

structure. When squeezed about 2/3 of the peat

escapes between the fingers. A small quantity of

pasty water may be released. The plant material

remaining in the hand consists of residues such as

roots and fibres that resist decomposition.

H8

French and North American based

on Mangan

OORGANIC

SOIL

aH7 – H10

hSapric or

Amorphous

H4 – H6

fHemic or

Moderately

decomposed (semi

fibrous)

H1 to H3

PtFibric or fibrousPEAT

SymbolQualifying termsVon Post

degree of

humification

Organic

components

Landva (classification for engineering

purpose)

Soils with Organic content. CO, MO.

SG > 2.4. NMC< 100%. LL< 50 %

95 to 99 %

Organic soils. O. NMC = 100 to 500 %. Fibre

content insignificant .LL > 50 %

40 to 95 %

Peaty Organic Soil. PtO. SG = 1.7 to 3.0.

NMC = 150 – 800%. Fibre content < 50 %. H8

to H10

20 to 40 %

Peat. Pt. SG < 1.7. SG < 1.7. NMC > 500 %.

Fibre content > 50 %. H1 to H8

0 to 20 %

Description Ash content

(less ash

means higher

organic

content)

Landva – Ash content versus

moisture content

LOCAL DESCRIPTION

(SARAWAK)

• Tai and Lee (Sibu Conference, 2002)

• Wong King Min (Sibu Conference, 2002)

Tai and Lee (2002)Adopted the common terms Ombrogeneous or

Fibrous Peats as distinct from Topogeneous and Amorphous Peats (from Lam)

Ombrogeneous or fibrous peat (deposited above flood levels)

• Mc = 300 to 2000 %.

• Bulk density = 1.1 to 1.4 mg /m3.

• pH = 3 to 5

• Pile up of slightly to moderately decomposed, loose tree trunks, branches, leaves, roots, fruits and other vegetable remains.

• Overlay Topogeneous or Amorphous peat

Tai and Lee (2002)

Topogeneous or amorphous peat.

• Mc = 100 to 300 %

• Bulk density = 1.3 to 1.6 mg /m3

• pH = 3 to 5

• Clayey peat. Slightly to moderately decomposed

leaves, reeds and wood with clastic sediments;

usually more compact with layered structure

• Deposited under flood conditions below the

fibrous peat zone

Wong Kin Min (2002)

Un-decomposed to partially

decomposed peat. Acidic

> 1200

%

Partially to moderately decomposed

peat. Ash content 5 – 18 %. High fibre

content. pH = 3.5 to 5

600 to

1200%

Completely to moderately decomposed

peat. Ash content = 10 – 50 %. pH = 5

to 7.5

200 to

600 %

Organic clays with density greater than

10 kg /m3. pH = 5to 7.

NMC 70

to 200%

PEAT PROPERTIES

Basic Peat Properties

• Ash content = 100 – Organic content

• Ignition loss close to the value of the organic content.

• There can be much confusion from the different classification schemes. It is better to just think in terms of the natural moisture content of peat since, in any case, the moisture content is correlated to a variety of properties.

BASIC PROPERTIES

GENERAL.

• Much published data internationally relating peat properties to natural moisture content, ash content (100-organic content),ignition loss (very close to organic content)

• Pity little such correlations from Malaysia. Some collection of Sarawak correlations by Wong Kin Min (2002)

ARE QUALITATIVE

DESCRIPTIONS NECESSARY IF

IT IS POSSIBLE TO RELATE

ESSENTIAL ENGINEERING

CHARACTERISTICS TO• Natural moisture content

• Organic content

• Ash content

?

SETTLEMENT

S∞ = primary consolidation + secondary

consolidation

S∞ = (Cc / ( 1 + e0)) H Log (1 + ∆p/p0’)

+ Cα H log (t / tp)

BASIC PROPERTIES FOR

SETTLEMENT ESTIMATES

Bulk density range from 1.0 to 1.9 tons / m3.

Bulk density + ground water >>>>> po’ – effective

overburden pressure

Lower bulk density related to higher organic

content (higher ignition loss)

Ignition loss >>>>> bulk density >>>>> po’

BULK DENSITY – IGNITION LOSS

SPECIFIC GRAVITY

Specific gravity well related to ash content.

SG values range from 1.4 to 2.4.

Lower SG values are for higher organic

contents

Ash content >>>>>SG >>>>>> bulk density

>>>>> effective overburden pressure po’

S.G. – ASH CONTENT

S∞ = (Cc / ( 1 + e0)) H Log (1 + ∆p/p0’)


Know po’

VOID RATIO AND

COMPRESSIBILITY

Natural moisture content >>>>>>>initial void

ration e0 (Dutch correlations)

Natural moisture content >>>>>>

compressibility index Cc (Mesri)

PEAT. Initial void ratio - NMC

u u X Q)

"'C c:: c::: 0

10

C/) 1 t/)

~ c.. E 0 u

Peats o James Bay Peat o Middleton Peat

6. Data from Literature

• • •

Soft Clay & Silt Deposits • From Mesri et al. 1997

0.1 L---~--~~~~~--~--~~~~~--~ 10 100 1000

Natural Water Content, w0, 0/o

Fig. 10. Empirical correlation between compression index, Cc, and natural water content, w 0 , for peats as well as soft clay and silt deoosits

S∞ = (Cc / ( 1 + e0)) H Log (1 + ∆p/p0’)


Know p0’ from organic content and ignition loss

Know Cc/ (1+e0) from natural moisture content

H = peat thickness

∆p = applied pressure

Therefore can estimate primary consolidation

settlement

-X

~ 0.8 c: c 0 Cl) (/)

<l> .._ c_

E 0 ()

~ rn

"'0 c: 0 u Q)

0.6

0.4

0.2

o Middleton Peat

• James Bay peat

••• • •

0

.......____ C0 _1 Cc = 0.053

(J) 0. 0 ~L....Io...ll ................................................. ..&...looo. ................................................. ~~ ........................ ---. .......

0 2 4 6 8 10 12 14

Compression Index, Cc

=ig. 12. Secondary compression index, Ca., versus compression ndex, Cc, for Middleton and James Bay peats

Cα – coeeficient secondary

consolidation

Cc>>>>>>>>> Cα (from Mesri)

S∞ = (Cc / ( 1 + e0)) H Log (1 +

∆p/p0’)


H =peat thickness

tp = time for end of primary

consolidation

Therefore can estimate secondary

consolidation and total settlement

S∞

PEAT. Settlement parameters

PRIMARY CONSOLIDATION

• Bulk density related to Ignition Loss. Therefore po’ can be estimated.

• Initial void ratio (eo) related to Natural moisture content

• Cc (compressibility index) related to natural moisture content

• Therefore can obtain Cc / (1 + eo) from natural moisture content

PEAT. Settlement parameters

Coefficient of secondary consolidation Cα

related to Cc

Therefore from natural moisture content, organic

content or ignition loss, all the settlement

parameters can be obtained.

PEAT. Void ratio and permeability

Void ratio changes on application of load.

Void ratio related to coefficient of

permeability

K range from 10-6 to 10-11 m / sec. Peat is

not so permeable.

Therefore can estimate Cv from k at different

pressures

o James Bay Peat o Middleton Peat 28 11 Peats from literature

24

Q) 20 . 0 -~ 16 "0 ·-~ 12

8

4

0 L..J..jWJ.III-L.LWJ .....lL...LI.W -LLW

10-14 10-12. 10-10 10-8 1 o-6 10-4 10-2

Coefficient of Permeability, kv, m/s

Fig. 2. Data on coefficient of permeability, ku, of fibrous peats within frame of reference of permeability data for sodium clay minerals, soft clay deposits, including Mex..ico City clay, and clean sand

4

2

0 0

o James Bay Peat o Middleton Peat 6 P~eats fro,m literature • Clay and Silt Deposas

5 10 15

OAO 0 0 ;y

0 a

20

In situ Void Ratio, e0

25

F1ig. 3. Relation hip between Ck=Ae! a log ku a·n,d in ito void ratio, e0 • for tibr~ous peats compared to that of , oft clay and . ilt d:epo it

20

16

8

4

0 0

Kozeny-Carman Ck= 1.1 e

4 8 12

Montmorillonite ck= 0.7 e

Fibrous Peat ck= o.2s e0 r Fissured Shales

___ ck= o.os e0

16 20 24 28

In situ Void Ratio, e0

32

Fig. 4. Explanation of magnitude of Ck/ e or Ck/ e0 in terms of fiv, materials with different pore-size distribution

PEAT. BASIC STRENGTH

PROPERTIES

PEAT. Strength properties

Undrained shear strength:

• Cu very low < 10 kPa for fibrous peat.

• Not possible to use vane shear tests because of fibres

• Piezocones useful for profiling only. Cone resistance < 100 kPa

• Mckintosh useful for shallow peat. MP = 5 to 10 blows / 300 mm for peat less than 3 m thick. Wong Kin Ming (2002) show MP of about 40 for peat depth of 7.0 m – Careful when interpreting Mckintosh probes

Peat . Undrained shear strength

• Difficult to measure

• Field vane shear tests not reliable

especially for high fibre content – can

result in abnormally high strength values

• Difficult to obtain undisturbed samples for

laboratory strength tests.

• Landva concluded that vanes and cone

penetrometers of little use.

100 70

50

30

ro 20 a.. ~

. - 10 G: - 7 0 :;)

C/l 5

3

2

1 6

I - s. (FV)"95 kPa

e =7.6 ~

0

8

~0

~

(40r sj FV) = e

Samson & La Rochelle (1972) Data

0 0 0 ~ slo() (f=V):::zao~

0~~ eo

1 .... 0 0 0 0 suO (FV) Jo ~10 (f=V):: 140te

00 0

<DO 0 0 0 0

0 S.O (I=V)::: "fO/e 0 0

0

10 12 14 16 18 20 22 24 26 Void Ratio

Fig. 20. Undrained shear strength of urfic ial fibrous peat depo it , from fie ld vane test, s11(FV), ummarized in terms of in situ void ratio , as well as S11(FV) versus e according to Eq. ( 13), together with preloading data of Samson and La Rochelle ( 1972)

Peat Effective / drained strength

parameters

PEAT. Effective and drained

strength

Usually very high friction angles compared to

soft clay due to interlocking and stretching

of the fibres.

CIU triaxial tests give

• Batu Kawa Road – Phi’ = 40 to 42 degrees

• Dutch peat - Phi’ = 35 to 52 degrees

• Soft clay typically –Phi’ = 24 degrees

200

ro a.. 150 ::t::. .. N .........

:?> 100 0 .

"t'-" .. ~ 50

K0P= 0.35

• Yield Point • Direct Shear

o~~~~~~~~~~~~~~~

0 50 100 150 200 250 300

( cr'1 + cr'3 )/2, kPa

Fig. 17. Effective stress paths of Middleton peat specimens con soli· dated under equal all-around pressure or under laterally constrainec condition and then subjected to undrained axial compression, anc peak shear strength versus effective normal stress <J~ from thre<: drained direct shear tests

Table 5., Friction Angle of Fibrous Peats from Triaxial Compression Tests on Vertical Specimens

~Vo <P' Source Peat (%) (degrees)

Adams ( 1961 ) Mu ,keg 375- 430 50- 60 A.dams ( 1965) Moo .e River 330-600 48

Ozden et al. (1970) Mu keg 800 46

Tsushima et al. ( 1977) Muck 52~60

Yasuhara and Tak:enaka (1977) ~Otnono 50- 60 Tsushima et at (1982) Muck 51

Edil and Dhowian (1981) Middleton 500-600 57 and Edil and Wang (2,000)

Portage 600 54

Landva and LaRochelle (1983) Escuminac 1 ,240=-1 ,380 40--50

Marachi et al .. (1983) San Joaquin 200-500 44 Yamaguchi et al. (1985a,c,d) Ohmiya 96(}--..l ' ] 90 51-55

Urawa 980-1,260 53

Ajlouni (2000) Middleton 510-850 60

Friction angle – Irish peat

C’ = 5.5 to 6.1 kPa

Φ’ = 36.6 to 43.5 degrees

Hanrahan -

backcalculation

36 degrees for NMC of 710%

43 degrees for NMC of 575%

Sodha

55 degrees for NMC of 1200 to

1400%

Farrel and Hebib

Φ’ (degrees)Author

PEAT. Strength increase

The increase in strength with effective pressure is much higher for peat than soft clay

• Soft clay cu/po’ = 0.25 typically

• Peat cu/po’ = 0.54 to 0.72

The higher ratios are for the higher organic content. The interlocking of fibres give very high drained strength; same reason for the higher φ’

Middleton Peat

rn 100 a.. su(TC)/cr'vc =0.53 ~ ... ..-..... u ~ ......_.....

:J 50 (/) 0 lTC

• K0TC

0 0 50 100 150 200

a'vc' kPa

Fig. 19. Relationship between undrained shear strength from compression mode of shear defined at phase transformation yield point, ~u(TC), and vertical consolidation pressure, cr~, for Middleton peat

Table 6 . su(TC) I a~c of Fibrous Peats

Wo

Source Peat {%) s u(TC) I a ~c

Moran et al. (1958) Antioch, Algiers 230- 1,000 0.48- 0.60

Lea and Brawner (1959) Burnaby 400-1 ,200 0.47- 0.58

Adams (1965) Moose River 330-600 0.68

Forrest and MacFarlane Ottawa 900-1 ,200 0.50 (1969)

Yasuhara and Takenaka Omono 0.54 (1977)

Tsushima et al. (1977) 0.52- 0.54

Dhowian (1978) and Middleton 500- 600 0.55- 0.75 Edil and Wang (2000)

Portage 600 0.70

Yamaguchi et al. Ohmiya 960-1,190 0.55 ( 1985a,c,d

Urawa 980- 1,260 0.52

Den Haan (1997) 0.54-0.78

Aj louni (2000) Middleton 510-850 0.53a

aDefined at ·pha e transformation vield point.

Cu/p0’

0.45Hazawa

1.23Landva and la

Rochelle

0.4 to 0.8 (from CIU triaxial)

0.3 to 1.5 (from vanes)

Edil (US)

0.4 to 0.55 (from CIU triaxial)Carlsten

(Ireland)

Cu / p0’Author

IMPLICATIONS OF HIGH φ’ ,

HIGH Cu/p’ and HIGH Cv

• Certainty of appreciable gain in strength

• Encourages stage construction for

construction of high embankments

OTHER PEAT PROPERTIES

OTHER PEAT PROPERTIES

• Cold

• Acidic

• Oxygen free environment

• Bacteria immobilized

• Mummifies / preserves dead bodies

• 2300 year old bodies have been recovered

form European peat during peat mining

ANCIENT HUMAN REMAINS (2300 YEARS OLD) UNEARTHED

FROM EUROPEAN PEAT SWAMPS (BBC)

SOIL INVESTIGATIONS

IN PEAT

Soil Investigations

Landva : For fibrous peat, small scale tests

such as vanes and cone penetrometers of

little use.

Vane shear tests meaningless – fibres are

torn rather than sheared, Likely to

completely over-estimate the shear

strength.

PEAT. Soil Investigations

(i) Difficulty in obtaining undisturbed samples of peat especially for higher organic content

(ii) Strategy is to obtain disturbed samples (use peat augers) and carry out:

• Natural moisture content;

• Ignition loss;

• Organic content;

• Ash content

PEAT. Soil Investigation

With the basic properties use published correlations to :

• Obtain consolidation parameters for settlement estimates.

• Obtain strength parameters at different stages of embankment construction from consolidation up to that stage.

NECESSARY to obtain properties of soft clay beneath peat.

• Vane shear strength;

• Consolidation parameters;

PEAT. Soil Investigation

NOTES

• Careful about boreholes. Inexperienced

driller can record absence of peat

• Use peat augers on a grid pattern

• Use Mckintosh probes on a grid

pattern(shallow peat)

• Boreholes and piezocones for profiling

• Local knowledge

CONSTRUCTION ON PEAT

ANCIENT HISTORY

HOW ANCIENT MAN CROSSED PEAT

SWAMPS

FROM ARCHEOLOGICAL FINDINGS

AT SOMERSET, SOUTHERN ENGLAND

MEDIEVAL TIMES

Corduroy Roads

Discovery in UK of roads from Roman days.

Roads dated at between 900 to 1020AD

MEDIEVAL WOODEN TRACK,

WALES, 900 TO 1020 AD

CROSSING SWAMP ON

CORDUROY ROAD, UK 1815

CORDUROY ROAD

Earliest 4000BC (Glastonbury UK)

to 20th Century

CORDUROY ROAD.UNION

ARMY. AMERICAN CIVIL WAR

CORDUROY ROAD

WORLD WAR II

Extensively used by German Army during invasion of Russia

According to Antony Bevar author of “STALINGRAD”

“In some places, where no birch trunks came to hand to make corduroy roads, the corpses of Russian dead were used instead as planks.”

MALAYSIA 1970 TO 1980s

EARLY ROAD CONSTRUCTION ON PEAT

• Modern earthworks equipment

• End tip approach

• Brute force

• Not a lot of thinking

• No past history then

PEAT . Filling over Peat

PLACING FILL OVER PEAT

• Very , very important consideration

• Peat swampy and inaccessible except to light

equipment. Often soil inv equipment has to

access on timber planks

• End tipping will cause mud waves, severe

lateral movements, loss of fill as fill mixed with

peat. Volume of fill loss can be immense.

• Excavators known to have sunk into peat

Planks for soil investigation,

Machap, Johore

PEAT. Uncontrolled filling

PEAT. Uncontrolled Filling

Air Baloi Road, Johore

PEAT. Uncontrolled filling

Air Baloi Road, Johore

CONTROLLED FILL PLACEMENT

ON PEAT

AN ABSOLUTE NECESSITY

Methods to ensure stable fill

placement

Drain the peat to lower ground water table by

0.5m to 1.0m. Enable access by light

earthworks equipment and placement of fill in

dry conditions in thin layers.

Timber matting.

Geotextile bamboo fascine mattress.

PEAT. Filling in dry conditions

• Critical to start with site drainage and lower

ground water by about 1.0 m.

• Achieve drainage by a network of drains and

allow peat to drain for several weeks

• Drain construction slow. Progressive deepening.

Maybe ½ metre each increment then allow

drainage for few weeks then next increment.

• Peat fibres will then interlock and stretch under

load like a thick geotextile cushion (high φ)

PEAT. Filling in dry condition

• If gravity drainage not possible , will need

to pump.

• When peat surface is well drained, place

first layer of less than 0.5 m using light

track dozers.

• Tree trunks or timber waste from site

clearance will be useful to help form the

access.

PEAT . Drainage

PEAT. Large Areal Drainage by DID

(Johore)

PEAT. Large Area Drainage by DID

(Johore)

PEAT. Drainage due to dewatering

for peat excavation (Machap)

PEAT. Timber matting

PEAT. Geotextile bamboo Fascine

Local innovation originally developed for filling

over disused mining slime ponds (see Toh,

Chee, Lee, Wee)

First used in Sarawak for peat at Petra Jaya

Boulevard and Petra Jaya ring road

Bamboo frame tied by wire to provide stiffness

and access

Highly extensible geotextile to stretch without

tearing and contain mudwave ahead of the fill.

PEAT.Geotextile – bamboo fascine

Geotextile must have high permeability to

enable dissipation of pore pressures

First layer of fill about 500 mm must be sand

to enable pore pressures to be dissipated

Significant mud waves can form if low

permeability soil used as first layer fill

Use when not possible to drain low lying peat

areas

PEAT. Geotextile bamboo fascine

Geotextile bamboo fascine

Geotextile Bamboo Fascine

Geotextile Bamboo fascine

Geotextile Bamboo Fascine

Geotextile bamboo fascine

Geotextile Bamboo fascine

PEAT. Hydraulic sand filling

Good way of filling over peat because the

sand can be placed by pumping in thin lifts

and spread over a wide area.

No need to drain the peat and no need for

timber matting or geotextile bamboo

fascine.

Was used successfully for the Matang

Highway, Kuching

Peat Swamp . Matang

Peat Matang. Hydraulic sand fill

Peat. Matang. Hydraulic sand fill

CASE HISTORIES

PEAT. CASE HISTORIES

• Miri Bypass road – Stage construction of road embankment

• MJ City. Batu Kawa (First phase) filling with surcharge

• Oya-Balingian Road

• Matang Highway (hydraulic sand fill + preload)

• Sylhet road (Bangladesh) – Stage construction with geotextile reinforcement

• Khoo and Yam. Pagoh

• Peat replacement (Air Itam to Johor Baru NORTH SOUTH Expressway)

• Sibu floating road

Embankment stability

(repeat important points)Very low initial Cu < 10 kPa will give rise to filling and

stability problems if embankment built too rapidly

Punch type bearing capacity due to high ratio of embankment to foundation stiffness

High Cu/p’ of 0.5 to 0.8 and high friction angle favoursstage construction. Rest periods between lifts to enable gain in strength to take place. The gain in strength comes quickly from the more rapid pore pressure dissipation especially in the early stages.

PEAT. Embankment stability

(repeat important points)

CARE

Soft clay often found beneath peat. If peat is

relatively thin, slip circle extends into soft

clay, and stability not governed by peat but

by soft clay.

Examples of Stage construction in case

histories.

PEAT. Settlement

(repeat important points)

Estimates of peat settlement made in the same manner as for soft clay except that:

Cc/(1 + eo) = 0.4 to 0.5 (higher than clay)

Cα contributes to long term settlement.

Experience shows that from use of above parameters with cv = 5 sq m per year, fairly good estimate of settlement can be made.

PEAT. Settlement

(from measurements)Commonly significant settlement occur during the

building up of the embankment.

Settlement can be up to between 50 to 65 % of the peat thickness.

Longer term settlement influenced more by the consolidation of the underlying soft clay.

Extra earthworks must be envisaged and allowed for.

Settlement of peat addressed in case histories

PEAT CASE HISTORY.

MIRI BY PASS ROAD

MIRI BY PASS ROAD

S = 0.8 m1.2 m peat

1.2 – 8.5 m soft

clay

SP 6

S = 1.05 m1.5 m peat

1.5 – 19 m soft

clay

SP 4

S = 1.7 m3 m peat

3 – 18 m soft

clay

SP 2

SP2 @ CH2+700 Road 1

2

3

4

5

6

0 200 400 600 800 1000

T IM E (DAY S)


-2000

-1500

-1000

-500

0

0 200 400 600 800 1000

TIME (DAYS)

SETTLEMENT (mm)


2

3

4

5

6

0 200 400 600 800 1000 1200

T IM E ( DAY S)


-1200

-1000

-800

-600

-400

-200

0

0 200 400 600 800 1000 1200

TIME (DAYS)

SETTLEMENT (mm)


2

2.5

3

3.5

4

0 200 400 600 800 1000

T IM E (DAY S)


-800

-600

-400

-200

0

0 200 400 600 800 1000

TIME (DAYS)

SETTLEMENT (mm)

MJ CITY BATU KAWA

4 to 6 m peat over limestone

Surcharge over 200 days

Settlement up to 2 m

MJ CITY. BATU KAWA

BATU KAWA NEW TOWNSHIP

-2.5

-2

-1.5

-1

-0.5

0

0 50 100 150 200 250

TIME (days)

SETTLEMENT (m)

4D 4G 5C 5G 6E 7B

OYA BALINGIAN ROAD

PEAT DEPTH UP TO ABOUT 5.5 M

SURCHARGE FOR ABOUT 9 MONTHS

MEASURED SETTLEMENT S UPTO 3.9 M

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1.100

1.200

1.300

1.400

1.500

1.600

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

2.600

2.700

2.800

2.900

3.000

3.100

3.200

3.300

3.400

3.500

3.600

3.700

3.800

3.900

4.000

13-Apr-04

16-Apr-04

19-Apr-04

22-Apr-04

25-Apr-04

28-Apr-04

1-May-04

4-May-04

7-May-04

10-May-04

13-May-04

16-May-04

19-May-04

22-May-04

25-May-04

28-May-04

31-May-04

3-Jun-04

6-Jun-04

9-Jun-04

12-Jun-04

15-Jun-04

18-Jun-04

21-Jun-04

24-Jun-04

27-Jun-04

30-Jun-04

3-Jul-04

6-Jul-04

9-Jul-04

12-Jul-04

15-Jul-04

18-Jul-04

21-Jul-04

24-Jul-04

27-Jul-04

30-Jul-04

2-Aug-04

5-Aug-04

8-Aug-04

11-Aug-04

14-Aug-04

17-Aug-04

20-Aug-04

23-Aug-04

26-Aug-04

29-Aug-04

1-Sep-04

4-Sep-04

7-Sep-04

10-Sep-04

13-Sep-04

16-Sep-04

19-Sep-04

22-Sep-04

25-Sep-04

28-Sep-04

1-Oct-04

4-Oct-04

7-Oct-04

10-Oct-04

13-Oct-04

16-Oct-04

19-Oct-04

22-Oct-04

25-Oct-04

28-Oct-04

31-Oct-04

3-Nov-04

6-Nov-04

9-Nov-04

12-Nov-04

15-Nov-04

18-Nov-04

21-Nov-04

24-Nov-04

27-Nov-04

30-Nov-04

3-Dec-04

6-Dec-04

9-Dec-04

12-Dec-04

15-Dec-04

18-Dec-04

21-Dec-04

24-Dec-04

Time

Settlement(m)

CH28+350

CH28+600

CH29+100

CH28+850

CH24+600

0.0000.0500.1000.1500.2000.2500.3000.3500.4000.4500.5000.5500.6000.6500.7000.7500.8000.8500.9000.9501.0001.0501.1001.1501.2001.2501.3001.3501.4001.4501.5001.5501.6001.6501.7001.7501.8001.8501.9001.9502.0002.0502.1002.1502.2002.2502.3002.3502.4002.4502.5002.5502.6002.6502.7002.7502.800

2-Feb-04

5-Feb-04

8-Feb-04

11-Feb-04

14-Feb-04

17-Feb-04

20-Feb-04

23-Feb-04

26-Feb-04

29-Feb-04

3-Mar-04

6-Mar-04

9-Mar-04

12-Mar-04

15-Mar-04

18-Mar-04

21-Mar-04

24-Mar-04

27-Mar-04

30-Mar-04

2-Apr-04

5-Apr-04

8-Apr-04

11-Apr-04

14-Apr-04

17-Apr-04

20-Apr-04

23-Apr-04

26-Apr-04

29-Apr-04

2-May-04

5-May-04

8-May-04

11-May-04

14-May-04

17-May-04

20-May-04

23-May-04

26-May-04

29-May-04

1-Jun-04

4-Jun-04

7-Jun-04

10-Jun-04

13-Jun-04

16-Jun-04

19-Jun-04

22-Jun-04

25-Jun-04

28-Jun-04

1-Jul-04

4-Jul-04

7-Jul-04

10-Jul-04

13-Jul-04

16-Jul-04

19-Jul-04

22-Jul-04

25-Jul-04

28-Jul-04

31-Jul-04

3-Aug-04

6-Aug-04

9-Aug-04

12-Aug-04

15-Aug-04

18-Aug-04

21-Aug-04

24-Aug-04

27-Aug-04

30-Aug-04

2-Sep-04

5-Sep-04

8-Sep-04

11-Sep-04

14-Sep-04

17-Sep-04

20-Sep-04

23-Sep-04

26-Sep-04

29-Sep-04

2-Oct-04

5-Oct-04

8-Oct-04

11-Oct-04

14-Oct-04

17-Oct-04

20-Oct-04

23-Oct-04

26-Oct-04

29-Oct-04

1-Nov-04

4-Nov-04

7-Nov-04

10-Nov-04

13-Nov-04

16-Nov-04

19-Nov-04

22-Nov-04

25-Nov-04

28-Nov-04

1-Dec-04

4-Dec-04

7-Dec-04

10-Dec-04

13-Dec-04

16-Dec-04

19-Dec-04

22-Dec-04

Time

Settlement(m)

CH25+600

CH25+850

CH25+350

CH25+100

CH26+600

Damaged

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.000

1.100

1.200

1.300

1.400

1.500

1.600

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

2.600

2.700

2.800

2.900

3.000

3.100

3.200

3.300

3.400

3.500

3.600

3.700

3.800

3.900

4.000

27-Dec-03

30-Dec-03

2-Jan-04

5-Jan-04

8-Jan-04

11-Jan-04

14-Jan-04

17-Jan-04

20-Jan-04

23-Jan-04

26-Jan-04

29-Jan-04

1-Feb-04

4-Feb-04

7-Feb-04

10-Feb-04

13-Feb-04

16-Feb-04

19-Feb-04

22-Feb-04

25-Feb-04

28-Feb-04

2-Mar-04

5-Mar-04

8-Mar-04

11-Mar-04

14-Mar-04

17-Mar-04

20-Mar-04

23-Mar-04

26-Mar-04

29-Mar-04

1-Apr-04

4-Apr-04

7-Apr-04

10-Apr-04

13-Apr-04

16-Apr-04

19-Apr-04

22-Apr-04

25-Apr-04

28-Apr-04

1-May-04

4-May-04

7-May-04

10-May-04

13-May-04

16-May-04

19-May-04

22-May-04

25-May-04

28-May-04

31-May-04

3-Jun-04

6-Jun-04

9-Jun-04

12-Jun-04

15-Jun-04

18-Jun-04

21-Jun-04

24-Jun-04

27-Jun-04

30-Jun-04

3-Jul-04

6-Jul-04

9-Jul-04

12-Jul-04

15-Jul-04

18-Jul-04

21-Jul-04

24-Jul-04

27-Jul-04

30-Jul-04

2-Aug-04

5-Aug-04

8-Aug-04

11-Aug-04

14-Aug-04

17-Aug-04

20-Aug-04

23-Aug-04

26-Aug-04

29-Aug-04

1-Sep-04

4-Sep-04

7-Sep-04

10-Sep-04

13-Sep-04

16-Sep-04

19-Sep-04

22-Sep-04

25-Sep-04

28-Sep-04

1-Oct-04

4-Oct-04

7-Oct-04

10-Oct-04

13-Oct-04

16-Oct-04

19-Oct-04

22-Oct-04

25-Oct-04

28-Oct-04

31-Oct-04

3-Nov-04

6-Nov-04

9-Nov-04

12-Nov-04

15-Nov-04

18-Nov-04

21-Nov-04

24-Nov-04

27-Nov-04

30-Nov-04

3-Dec-04

6-Dec-04

9-Dec-04

12-Dec-04

15-Dec-04

18-Dec-04

Time

Settlement(m) CH27+100

CH27+350

CH26+850

CH26+100

CH26+350

Damag

ed

MATANG HIGHWAY KUCHING

• PEAT THICKNESS UP TO 6 M

• SOFT CLAY BENEATH

• MEASURED SETTLEMENT LOW SINCE

HYDRAULIC FILLING MEABS

SETTLEMENT GAUGE INSTALLED

ONLY AFTER AT LEAST 1.0 M FILL IN

PLACE

Matang Highway

Monitoring of Settlement Along Centreline of Road (at CH 16 + 000 to CH 16 + 475)

Since the inception of Embankment Formation

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

Date

CH16+000

CH16+050

CH16+100

CH16+150

CH16+200

CH16+250

CH16+300

CH16+350

CH16+400

CH16+450

-200

-100

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

Number of Days

CH16+000

CH16+050

CH16+100

CH16+150

CH16+200

Ch16+250

CH16+300

CH16+350

CH16+400

CH16+450

MATANG HIGHWAY

PEAT CASE HISTORY. SYHLET

ROAD , BANGLADESH

• About 200 km North of Dhaka

• 0 to 4 m Peaty organic clay in places with

4m to 8 m soft clay beneath.

• Some places no peat only soft clay.

• Embankment up to 8 m high

• Stage construction to mitigate post construction settlement with gain in strength and geotextile reinforcements for stability

PEAT. SYLHET

• Fill placed over 1 year with rest periods.

• 1.0 to 1.8 m settlement in soft clay

• 2.4 m settlement in peat

• Roc PEC high tensile geotextile

reinforcement

• Geotextile bamboo for access.

SYLHET, BANGLADESH

Geotextile reinforced embankment

SYLHET, BANGLADESH

Sylhet. Geotextile and bamboo

SYLHET, BANGLADESH

Sylhet. Rock PEC geotextile

reinforcement

SYLHET, BANGLADESH

Sylhet. Reinforced embankment

Syhlet. Reinforced embankment


Stage construction

Geotextile reinforced

embankment. Settlement

Geotextile reinforced

embankment. Piezometers

Gain in strength

Stability analysis. Reinforcement

and gain in strength

Embankment buildup

Long term settlement

Stage construction

Settlement

Stability parameters

Stability analysis with

reinforcement

Embankment construction

EMBANKMENT ON PEAT

Khoo Kim Poh and Yam Seng Lam (PLB

Conference 1990).

• 5m high embankment on 2 m peat by

stage construction and surcharge

• Pagoh to Bukit Sulong Road diversion

Khoo and Yam

Khoo and Yam

• 1.4 to 1.7 m thick peat . NMC 300 to 600%.

• 0.4 to 1.6 m very soft organic clay with

pieces of decayed wood . NMC 150 to

200%

• 1.8 m soft to firm clay. NMC of 50%.

Khoo and Yam

!1 ! ' }

:..

:1 I I I I I I I

I ~

I I I I I

"!' -

:

51

WAIER lEAD II I RH I riEZONElU I 11 REDUCEI LEVEll

~ ~ ~ ... ~ ~ ... .:.

··~ --.. -Ni

'" ~ . -:

\ -c

:1 I..)

il > ) ... 'l'

~

':' ... -WATER HEAD II YELUW PIEZINEIER

I ll RUICED LEVEl l

~ -- ':" --.:. ... !' ... -WAIU ME AD II RED fiEZOMETU

I • IEOmO LEVEll - .. .... - ':" -..... ...

_ , I I I I I l I I I I I I I I I

~·~ ;· ~

=~ .. ;: --.. i -~ .: ... - ... ,. ;

j -. . --:· ,.

I :i \ I l =~ \ '---? it:'

i~ . -. -~-~ . --!: ; ·-: .. • :. ~ -

I : ~ I I=; I ! i I )

I il ~ ~ I il ~ f

... :;: -' ' ,. ,. ' ' -.. =

-

I ---

I .. ::

I ... =

I i ... -' ,. ' . ...

U!Ul Of fiLL PL AtED 1•1

PEAT EXCAVATION CASE

HISTORY

MACHAP TO AIR HITAM – 30 km of peat

NORTH SOUTH EXPRESSWAY

PEAT GENERALLY ABOUT 6 M

LOCALIZED AREAS UP TO 12 M

DEWATERING, COMPLETE REMOVAL,

REPLACE WITH COMPACTED FILL

CONE RESISTANCE ( MPa1) WATER PRESSLI£ tkPa)

0 0.4 0 ·8 t· 2 'I, ·6 2-0 2-4 -oo 0 t 00 200 300 400 500

....... 6

E -:t: 8 ..... 0.. w

0

'f " · ~

\

\ PEAT I

\. \:; fL-\. ~ ~ I~

Clo~y ~ IPEAT

~ L. \ ~ 1~

~ ' . ~ Soft I

~ \ CLAY

2

4

0 10 i.ii£: ._. 1

<:;;:

t2 [\ FHy ~rosttm line

I \

\ I

t4

Figure 1 Typical piez~ocone profile,

Scheme I Scheme D

Top of errtxnunent level

RL• Sm '--__;_...:.:....__ ______ ---1;3----...__Bo~of-~xcav~~-L---- RL 4 · ,.,.-""

. ----- --~-m -- ------.:~ CH. tO 800

Figure 3 Originally intended extent of excavation and replacement

0 0 to-+ 0 -

10

8

... 6 . • -, ' 4 I .. J 2 I

0

I ,-2 I . -4

igure 2

0 0 l() 0

"' (J)

+ + 0 Q -

O.G.L

CHAINAGE 0 10 G)

+ 0

Com pet en Residual Soil

Subsurface profile at the. trial site

0 0 0 &() m m + .... 0 0 - ....

Water table l I. ORIGINAL W'ATER l ABLE. CONOJTJONS 1 INACCESSIBLE TO PLANT Aftl'J· EQUPt.£NT

P'ea1

lml)r()Yed zone dUe to tOWif'ilg of. wcner -fObll . The area now oceesttie to plant--!

CJ1d equJpmwd.

2. INlTtAL DEWATE~AtNG. OF UMIITEO AREA TO ENABLE ACCESS BY EXCAVATION PLANT FOR IMTIAL EXCAVATI~1 .

orectkln ttf eJrcovation

I -------. I

Water fable onead of 1 .,._..;.;ln.;.;;.i .;..;ti.:;.ol~e:.:.:x-=-e.:::..ov.=....:a::...:~ t..:....::ion:..:...~~ =--· .......,. ... excovotion lcw·ered fo imprOiie ---1

conditions and ooc·ess

3!, 1INITI.AL EXCAVATION. AND LOWERING OF" WATER TABl.E. AROUND EXCAVATED PIT.

Ad VOncinQ fi II

AdvCI'ICJ'IG1 irnptOYtd conditions from lowering of wat•r tabte· oheod of e.cavo.tlon.

4 ADVANCING EXCAVATION WITH ADVANCING IMPROVED CONDITtONS AHEAD OF EXCAVATION.

J-egend :

0 Left hand toe of excovotion

+ Centreline of exc·avat,on

A Right hand toe of excavation

-4+---------.---------~--------~--------~--------~--------~ 10+700 1'0-t-750 10..,800 10+850 10+900 10+-950 11 tOOO

CHAINAGE ( Km)

Figure 9 Final' exca.vation le·vers

Maximum daily volume = 5 Million gallons

= 19 million litres

- 15 E -_J w > w _J

0

10-

IJJ 5 (.) :::)

0 w

Legend

-- Ground levels

--- Water level

@ Standpipe piezometer

Crest of § excavated slope

2115/90

21/6/90

Notes= I) Stondppes installed on 3015190 2) 2m deep droo at this chainage completed between

716190 to 916190. 3)Top ·4m excavated from 17 I 7190 to 21 I 7190 4)Remoinino peat excavated by 2617190

2m deep drain

------~--------------..:--------------r26/7/90

a:: 0~----------~----------~----------.-----------~----------~----------T ·30 40 50 60 70 80 90

DISTANCE FROM CENTRELINE OF EXCAVATION ( m )

Figure 6 Monitored phreatic surfaces at chainage 1 0 + 870

'9

....... Ea .. _J, - . Q: ._,...

~7 IJJ J: ue !2 ..... UJ ~5 0 N UJ 0::4

Legend

c ST-'t + ST- 2 <> ST- 3 4. S~-4

x ST-5 v ST-6

0 20 ~ ~ t0/5/90 30/5/90 19/6/90 9/7/90

T~ME ( da1ys )~

eo too 120 140 29/7/90 18/8/90 7/9/90 27/9/90

igure 7 Standpipe piezometer records at chainage 1 o~ + B 70

Machap. Peat excavation

Machap. Peat replacement

Machap. Peat Replacement

Machap. Peat replacement

PEAT CASE HISTORY

SIBU POLYSTYRENE ROAD

Joint full scale project between Dr C T Toh Consultant and Sibu Municipal Council

Located in the resettlement area of Sibuwhere the peat depth exceeds 20 m.

Flood prone area

Long term settlement of normal roads had resulted in high maintenance costs to councils

Sibu Polystyrene Walkway

• Idea was to construct a floating road like floating jetty

• Use polystyrene blocks and confine movements due to flooding only in the vertical direction. This is by connecting the polystyrene blocks to cables to belian piles at regular intervals

• Polystyrene covered by 100 mm thick lean concrete with BRC

CJ CJ

r----- 2 NO. BELIAN PILE ONE ON EACH SIDE ---~

(TOTAL 4 LENGTHS)

POLYSTYRENE (24 KG/CU . M.)

3m 3m 3m

---- 3 LENGTHS OF BELl AN PILES EMBEDDED IN PEAT-------

1 rFAT SIIRFAFF ANF WATER TABLE

PROPOSED POLYSTYRENE WALKWAY ON PEAT (LONG SECTION) (RESETTLEMENT AREA, SIBU) SCALE :- 1 : 75

CJ CJ L()

GALVANIZED MULTI STRAND STEEL CABLE

-10mm DIAMETER GALVANIZED STEEL ROD

GALVANIZED STEEL RING WITH SIDE OPENING

1 OOmm THK CONCRETE § ~WITH 1 LAYER BRC A4

•.............................................. ~ .........................................• ;;..: 'IC ;;..: 'IC ;;..: '- ~ [ ~ '- '( ~ '- '( ~

' ' '

JPOL YSTYRENE BLOCKSl ~--~~--~~-'J

3m

SECTION A-A SCALE : - 1 25

-25mm THK PLASTER

1 nRY nFASOC PEAT SURFACE AND WATER TABLE

0 0 LO

DRY DEASON PEAT SURFACE AND WATER TABLE

DRY SEASON LEVEL

L 1 OOmm THK CONCRETE

S rWITH 1 LAYER BRC A4

....... , .............. ···T·~~····••,••••••••••,••••••••••,•·········T··········T·················· -\ -\ r-' r-' }-

-------- }-

~LYSTYRENE BLOCKS] ,_ ~~~~~

r--~~~~~~~~~~~~~~~~~--t

3 LENGTHS BELIAN PILES BENEATH PEAT SURFACE

SECTION B-B SCALE : - 1 : 25

LOOSELY FITTING r SLIDING COLLAR I (GALVANIZED STEEL)

~EXTENDED COLLAR >++- ++<' (GALVANIZED STEEL)

~CIRCULAR STEEL COLLAR NAILED TO BELIAN PILE (GALVANIZED STEEL)

Sibu Polystyrene walkway

SIBU POLYSTYRENE WALKWAY

Sibu Polystyrene Walkway

Sibu polystyrene walkway

SIBU POLYSTRYRENE

WALKWAY

Settlement of peat after

drainage due to

decomposition

SETTLEMENT OF DRAINED

PEATLAND• Drainage of peat results in decomposition of the

peat above ground water.

>>>>>Lowering of the ground level and higher ground water relative to peat surface;

• Agriculture requires dry ground and therefore continuous deepening of surface drains and continuous lowering of ground water;

>>> Continuous decomposition of peat above ground water

>>> Continuous lowering (settlement) of peat surface due to decomposition


PEAT GROUND

The average rate of lowering of the peat

surface in Sarawak is about:

• 100 mm per year for fibrous peat;

• 50 mm per year for amorphous peat.

Therefore a 3 m peat layer will disappear in

about 30 year unless surface drainage

becomes impossible.


PEAT

New Zealand records of settlement of

reclaimed peat swamp for agricultural /

horticultural purposes since 1924 showed:

• Ground subsidence / peat thickness

reduction of up to 60 mm per year.

• Higher subsidence for deeper peat areas.

8 ~------------------------------------------~~~~,

6

0

e Rukubia 0 Hauraki 9 Moanatuatua

0 2 4 6 8 10 12 14 16

Original peat thickness (m)

Figure 3: Subsidence rate, of peat following1 conversio·n at Rukuhiat Hauraki (data from M~cLeod et al" 21003)~, and Moanatuatua (data from McKenzie and Mcleod,

.8 ~--------------------------------------------~~~


PEAT GROUND

Implications on stabilized road.

• The surrounding peat level will be lowered at a rate higher than the post construction settlement if design criteria of post construction settlement of road too strict.

• Culverts will not function within a few years.


PEAT GROUND

• There is therefore a need to re-look the design

criteria for settlement of roads in peat area if

there will be agriculture in surrounding areas.

• If the settlement criteria is too strict, the

surrounding ground will , in the long run, be

lower than the embankment toe level.

• Culverts will cease to function in a short while.

PEAT AND THE

ENVIRONMENT,

CARBON STORAGE/RELEASE

AND

CLIMATE CHANGE

CARBON STORAGE AND

CARBON RELEASE

WHEN PEAT IS SODDEN >>> CARBON

LOCKED INSIDE.

WHEN EXPOSED TO WIND AND SUN,

THE PEAT WILL DRY OUT >>>

TRANFORMATION FROM AN

ABSORBER OF CARBON TO A MASSIVE

SOURCE OF CARBON

PEAT SWAMP CARBON

STORAGE

CLEARING PEAT SWAMP RESULTS IN

GREATER SUSCEPTIBILITY TO PEAT

FIRES.

HAZE IN S. E. ASIA DUE LARGELY TO

PEAT FIRES.

RESULTS IN RELEASE OF CARBON

DIOXIDE TO ATMOSPHERE

ADDS TO GLOBAL WARMING

1007 FIRES IN SOUTH EAST

ASIA

• Estimated 2.67 billion tons of greenhouse

CO2 released through burning of peat in

SE Asia in 1997.

• This is about 40% of 1 year of global fossil

fuel combustion.

RELEASE OF CO2 TO

ATMOSPHERE

• PEAT FIRES IN SOUTH EAST ASIA

ADDS SIGNIFICANTLY TO GLOBAL

WARMING

• BIG FEARS IS GLOBAL WARMING

THAWS FROZEN SIBERIAN PEAT>>>

GREAT RELEASE OF CO2 TO

ATMOSPHERE>>>>> ACCELERATES

GLOBAL WARMING

ILLEGALLOGGING OF PEAT

SWAMP

• Satellite photo of illegal logging in peat

swamp of Tengganu from MalaysiaKini

INDONESIAN PEAT FOREST

FIRE(from BBC)

PEAT FIRE (from BBC)

NATURAL INHABITANTS

PROBOSCIS MONKEY

Proboscis monkey

• Endemic in mangrove and peat swamps of

Borneo

• Climbs trees

• Web feet for swimming

• Voracious sexual appetite

DESTRUCTION PEAT SWAMPS WILL

DESTROY BIO - DIVERSITY

END OF LECTURE

THANK YOU

construction roads and highways on peat -...

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