Paper 7-Ir Chee SK
Paper 7-Ir Chee SK
Paper 7-Ir Chee SK
CONSTRUCTION OF
INFRASTRUCTURES ON
PEAT
Ir. Chee Sai Kim
DR. C.T. TOH CONSULTANT
This lecture will largely be about fills and
embankments since a stable platform is a
necessary part of infra-structure development
In order to explain the methods of
stabilisation of fill it is necessary to explain
important aspects of peat properties and
design. It is possible that some of the
contents of this lecture may have been
included by other lecturers
LECTURE TOPICS
• Occurrence and distribution
• Types and classifications
• Properties
• Soil Investigations
• Stability
• Settlement
• Methods of placing fills
• Considerations for foundations /drainage /
sewerage / water supply
WORLD PEAT DISTRIBUTION
Canada 1,500,000sq km 18%
USSR 1,500,000sq km
USA 600,000 sq km 10%
Indonesia 170,000 sq km 14%
Finland 100,000 sq km 34%
Sweden 70,000 sq km 20%
China 42,000 sq km
Norway 30,000 sq km 10%
Malaysia 25,000 sq km
Germany 16,000 sq km
Brazil 15,000 sq km
Ireland 14,000 sq km
Uganda 14,000 sq km
Poland 13,000 sq km
World wide peat distribution
Falklands 12,000 sq km
Chile 11,000 sq km
Zambia 11,000 sq km
15 other 1 to 99%
countries
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
• Trengganu – as deep as 4 to 5 m with soft clay
beneath in pockets inland from the coast
• Batang Berjuntai
SOIL MAP JOHORE
Peat
SARAWAK
SIGNIFICANT EXTENT OF PEAT
Some Examples
• SIBU TOWN – KNOWN TO BE AS DEEP AS 17 M
• BATU KAWA, kuching – 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
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.
Maps from study by
James R. Staub and A.
Gastaldo
Late Quartenary sedimentation
and peat development in the
Raja River delta, Sarawak, East
Malaysia 2003
Peat map Rajang delta (from above Sibu to the
coast. Along the coast fromKg Paloh to Bintulu
peat
GEOLOGICAL FORMATION
MODEL
for
BATANG RAJANG PEAT
Fibrous peat
Amorphous peat
Ground surface
Fibrous peat
Organic clay
Depth
PEAT CLASSIFICATION
CLASSIFICATION SYSTEMS
• Van Post System for agricultural purposes
• French and North American system
• Landva classification – more suitable for
engineering purposes
• Local (Sarawak) classification schemes
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 (fibrous, undecomposed)
to H10 (amorphous and organic clay,
completely decomposed).
Von Post System
H1 Completely un-decomposed. Releases clear water. Plant
remains easily identifiable. No amorphous material present.
fibrous
Organic soils
LOCAL DESCRIPTION
(SARAWAK)
Wong Kin Min (2002 Seminar on peat in
Sibu)
Sensible combination of the Van Post
system with moisture content and ash
content
Wong Kin Min (2002)
NMC 70 Organic clays with density greater than
to 200% 10 kg /m3. pH = 5to 7.
200 to Completely to moderately decomposed
600 % peat. Ash content = 10 – 50 %. pH = 5
to 7.5
600 to Partially to moderately decomposed
1200% peat. Ash content 5 – 18 %. High fibre
content. pH = 3.5 to 5
> 1200 Un-decomposed to partially
% decomposed peat. Acidic
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 + Δp/p0’)
+ Cα H log (t / tp)
Problem is that it is not possible to obtain
undisturbed sample of peat
Solution is to use correlations with basic peat
properties
BASIC PROPERTIES FOR
SETTLEMENT ESTIMATES
Step 1 – HOW TO ESTIMATE Po’- insitu effective
stress
Bulk density range from 1.0 to 1.9 tons / m3.
Test for ignition loss. Refer to chart to obtain bulk
density
(γ – γw) * Depth = po’
Ignition loss test bulk density ‘ po
BULK DENSITY – IGNITION LOSS
S∞ = (Cc / ( 1 + e0)) H Log (1 + Δp/p0’)
+ Cα H log (t / tp)
Éstimated po’
INITIAL VOID RATIO
Step 2 How to estimate initial void ratio e0
X 100 = % moisture
S∞ = (Cc / ( 1 + e0)) H Log (1 + Δp/p0’)
+ Cα H log (t / tp)
+ Cα H log (t / tp)
+ Cα H log (t / tp)
Upper body
– no head
TIMBER BRIDGE
REMAINS OF THE WOODEN BRIDGE UNEARTHED IN SOMERSET, UK
Probably more than 3000 years old
MEDIEVAL TIMES
Corduroy Roads – Planks and logs tied
together to form a wooden track
Discovery in UK of roads from Roman days.
Roads dated at between 900AD to 1020AD
(This year is 2014 AD) – so this Roman road
is 10000 years old.
Preserved in peat for 1000 years
MEDIEVAL WOODEN TRACK,
WALES, 900 TO 1020 AD
CROSSING SWAMP ON
CORDUROY ROAD, UK 1815
CORDUROY ROAD
Earliest 4000BC (Glastonbury
UK). Same method used up to
th
20 Century
CORDUROY ROAD.UNION ARMY.
AMERICAN CIVIL WAR 1895
CORDUROY ROAD
WORLD WAR II
Extensively used by German Army during
invasion of Russia. Germans surprised the
Russians by sending their tanks across
peat swamp
According to Antony Bevar author of the
book “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 – got muscle but no
brains
• 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 – same as 4000 years ago
PEAT. Uncontrolled filling
HEAVE OF PEAT
PEAT. Uncontrolled filling
Air Baloi Road, Johore
HEAVE OF PEAT
CONSEQUENCES OF
UNCONTROLLED FILLING
• No control on volume
• Very high volumes of earth used
• Large heave and lateral movements
• Variable fill thickness and variable thickness of peat
beneath the fill
• Highly unstable – FS of end tipped embankment = 1.0
when movements stopped
• High post construction settlement and differential
settlement – infrastructures will perform badly
• Very , very difficult to remedy
• Equipment left on top of fill known to have sunk into peat
CONTROLLED FILL
PLACEMENT ON PEAT
AN ABSOLUTE NECESSITY
Methods to ensure stable fill
placement
1. 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.
2. Timber matting (Like Corduroy roads)
3. Geotextile bamboo fascine mattress.
4. Hydraulic sand fill – pumping sand in thin
layers
PEAT. Filling in dry conditions
Peat drainage
• 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)
resulting in gain in strength
PEAT. Filling in dry condition
• If gravity drainage not possible , will need
to pump.
• When peat surface is well drained, place
first layer (sand) 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
embankment
peat Timber
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
Significantly larger 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
– usually about 800 mm grid
Tie by wire
PEAT. Geotextile bamboo fascine
Heave ahe
Of fill fron
Sand fill
Geotextile bamboo fascine
Geotextile Bamboo Fascine
Tear – sewing problem
Tear in
Geotextile
seam
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
Peat. Matang. Hydraulic sand fill
Peat. Matang. Hydraulic sand fill
Fibrous peat
at surface
Pipe
for conveying
sand /water
Peat. Matang. Hydraulic sand fill
Peat. Matang. Hydraulic sand fill
Peat. Matang. Hydraulic sand fill
Peat Matang. Hydraulic sand fill
after constructing sand platform
CONSIDERATIONS FOR
OTHER INFRA-STRUCTURES
(1) A stable platform is crucial for proper
performance of infra-structures
(2) A stable platform will still settle over time
but by a lesser amount
(3) Infrastructures like water supply,
sewerage, drains are more manageable
with a stable platform
INFRA-STRUCTURES ON A
STABLE FILL
• Surface drains should not be pile supported. There may be a need
to re-construct surface drains after a few years
• Sewer lines and manholes must be supported on piles
• Main water pipes should also be supported on piles
• Water pipes to houses may adopt hdpe pipes with a lot of slack
• Services entering buildings must be tied to the suspended ground
floor slab
• Buildings must be piled and with suspended ground floor slab
• Aprouns should not be hinged to ground beam – either cast
independently or tied to ground beam
INFRA-STRUCTURES ON
STABLE FILL
• Culverts beneath embankment are a problem.
Often piled. Pipe culverts should (where possible)
be supported on floating pile groups and be
allowed to settle as the soft clay beneath the peat
consolidates – this will reduce the differential
settlement in the longitudinal direction.
• If culverts are supported on piles driven to refusal
then there will be no settlement at the culvert and
this will cause significant differential settlement in
the longitudinal direction.
Criteria for settlement
• Must be related to what is achievable and related
to maintenance and also Capital costs
• Presently the JKR (Sarawak) criteria of 200 to
300mm in first three (3) post construction years
appears achievable for peat of less than 5m thick
(depends also on soft clay beneath). Normally
require a preload of 9 months.
• 90% consolidation to be achieved doesn’t make
any sense and is expensive and time consuming to
achieve
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
SETTLEMENT OF DRAINED
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.
THANK YOU