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8Th November 2008
U Kyaw Linn
Managing Director
Public Works
Ministry of Construction
General Characteristicsof Foundation
Definition
A foundation is a part of substructure.
Substructure
Foundation
This is FOUNDATION!!
Normally you don’t seeanything.
Because it is in the ground.
What do we expect the FOUNDATION not to do?
• NOT TO MOVE
• NOT TO FALL
• NOT TO SINK
What force effects the Foundation?
• VERTICAL FORCE: V
But, from where? V
M
H
• HORIZONTAL FORCE: H
• MOMENT: M
• Superstructure
• Substructure
• Vehicles
• Wind
• Earthquake
• Temperature
• Soil
• Surface and Underground Water ,etc...
What do we have to find out to calculate the forces?
• Span Length• Cross Section• Design Discharge and High Water Level• Size of Substructure• Wind Velocity and Direction• Earthquake Strength• Range of Temperature• Height of Embankment• Size and Weight of the Vehicles etc...
What should we do before Designing the Foundation?
• Define the length of bridge and span
• Define type and Size of Superstructure and Substructure
• Investigate Natural Conditions(Climate, Hydrology, Soil, Geography)
• Existing Structure at the Site
Foundation is the LASTpart to design.
What type of FOUNDATION are there?
• Spread (Direct)
• PC/RC Pile
• Steel Pile
• Caisson
• Steel Pipe Sheet Pile
• Diaphragm (Slurry) Wall etc...
General Characteristics of Foundation
Type of foundation
Bearing stratum
Spread foundation
Bearing pile Friction pileCaisson foundation
Underground slurry
wall foundation
Steel pipe sheet
pile foundation
A very soft layer exisits in the middle Δ ο ο ο ο ο ο ο ο ο ο ο ο x ο ο ο ο
A very hard layer exisits in the middle ο x Δ Δ ο ο ο ο ο ο Δ ο Δ ο ο Δ Δ ο
ο Δ Δ ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο
ο x Δ Δ Δ Δ Δ Δ Δ Δ ο ο Δ ο ο ο Δ ο
ο x x x x x x x x x Δ x x ο ο Δ x Δ
Possibility of liquefactiion exisits Δ Δ ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο
ο x x x x x x x x x x x x x x x x x
Δ ο ο ο ο ο ο ο ο ο ο Δ ο ο ο ο Δ Δ
x Δ ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο
x x ο ο ο ο ο ο ο ο ο ο Δ Δ ο ο ο ο
x x Δ ο Δ Δ ο ο ο ο Δ ο x x Δ ο ο ο
x x x Δ x x x x x x x Δ x x x Δ Δ Δ
ο ο ο ο ο x Δ ο x Δ ο ο ο ο ο ο ο ο
ο ο ο ο ο ο x ο ο x ο ο ο ο ο ο ο ο
The inclination is large (over above 30). ο x Δ ο Δ Δ Δ ο ο ο ο Δ Δ ο ο Δ Δ Δ
The bearing layer surface is very rough ο Δ Δ ο Δ Δ Δ ο Δ Δ ο ο ο ο ο Δ Δ ο
Δ ο ο ο ο ο ο ο ο ο ο ο Δ Δ ο ο ο ο
Δ ο ο ο ο ο ο ο ο ο ο Δ x ο ο ο Δ Δ
x ο ο ο x x x x x x x x x x Δ Δ ο x
Flow rate of ground water is over 3m/min. x ο ο ο ο x x ο x x x x x x ο Δ ο x
ο ο ο ο ο ο ο ο ο ο ο ο ο ο x Δ x x
ο Δ ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο ο
ο x Δ ο Δ Δ Δ ο ο ο ο ο Δ ο ο ο ο ο
ο ο ο ο ο ο ο ο ο ο ο ο ο ο Δ Δ Δ Δ
ο x Δ ο Δ Δ Δ ο ο ο ο ο ο ο ο ο ο ο
Bearing pile ο ο ο ο ο ο ο ο ο ο ο ο ο
Friction pile ο ο ο ο ο ο
Water depth : less than 5m ο ο ο ο Δ Δ Δ Δ Δ Δ x ο Δ x Δ Δ ο x
Water depth : not less than 5m x Δ Δ ο Δ Δ Δ Δ Δ Δ x Δ x x Δ Δ ο x
Small working space ο Δ Δ Δ Δ Δ Δ Δ Δ Δ Δ Δ Δ ο Δ Δ x Δ
Construction of diagonal pile Δ ο ο x x x Δ Δ Δ Δ x x x
Influence of poisonous gas Δ ο ο ο ο ο ο ο ο ο ο ο ο x ο ο ο ο
Vibration and noise prevention ο x x x Δ ο ο Δ ο ο Δ ο ο ο ο ο x ο
Influence on adjacent structure ο x x Δ Δ ο ο Δ ο ο ο ο ο Δ Δ Δ Δ ο
Legend ο : Very suitable Δ : Suitable X : Unsuitable
Foundation type
Selection condition
Foundation type selection chart
Open
Steel
pipe
sheet
pile
found
ation
Under
ground
contine
ous
w all
foundat
ion
Direct
found
ationReve
rse
Earth
drill
Deep
foundatio
n
Pneu
matic
Final
percu
ssion
Erupti
on
&agit
ation
Conc
rete
placin
g
All
casin
g
Caisson
foundation
R.C
pile
P.C.
pile
Steel
pipe pile
Final
percu
ssion
Erupti
on
&agita
tion
Conc
rete
placin
g
P.C,P.H.C pile Steel pipe pile
Inner digging pile foundationCast-in-place pile foundation
Under w ater
construction
The horizontal load is small in comparison with
the vertical load
The ground water level is close to the surface
The amount of spring water is vary large.Confined ground-water more than 2m from
surface ground
40-60m
60m and above
State of
ground
w ater
Sand,sand and gravel (30 ≤ N)
Surrounding
enviroment
Co
str
uctio
n
co
nd
itio
n
Driving pile foundation
The horizontal load is large in comparison with
the vertical load
Load level
Bearing type
Ch
ara
cte
ristic o
f str
uctu
re
The vertical load is small
(Effective span less than 20m)
The vertical load is ordinary
(Effective span 20m - 50m)
The vertical load is large
(Effective span more than 50m)
Gro
un
d c
on
ditio
n
Gravel diam: smaller than 5cm
5-10cm
10-50cm
The
intermidiate
layer has
gravels
Less than 5 m
5-15m
Soil
property of
State of
bearing
layerCohesive soil (20 ≤ N)
condition
until
reaching
bearing
layer
Depth of
bearing
layer
15-25m
25-40m
Caisson Foundation
Construction up to
120 m has been rechorded.
Well
Peum
atic
Cais
son
Pile Foundation
Cast In
Pla
ce P
ile
100
P.C
Pile
Ste
el P
ile
0
30
40D
irect F
oundatio
n
110
120
Depth
(m
)
60
70
80
90
10
20
50
Po
ssib
le b
y lo
we
rin
g
wa
teri
ng
le
ve
l
Foundation Forms And Constrution Depth
Th
e p
rob
lem
of fr
ictio
n
incre
ase
s w
ith
de
pth
Bore
d p
ileR
.C.D
There are four type of FOUNDATION
• Open Foundation
• Block Foundation
• Pile Foundation
• Well Foundation
Shallow Foundation
Deep Foundation
Spread (Direct) Foundation
Ground Improvement
Shallow (~8m)Many in Hilly and
Mountainous AreaWhen good bearing
ground exists at a shallow depth, a direct foundation is generally economicalSometimes with
Ground Improvement
Prestressed Concrete / Reinforced Concrete Pile
Point Bearing Pile
Friction Pile
Deep (8~60m)Pre-cast for PC, RCCast-in-place available for RCMany for River Bridges
(Cast-in-place)Many in Bay Area (Pre-cast)
Steel Pile
Deep (15~60m)Ready-madeMany in Bay Area
Well Foundation
Deep (10~40m)Many for Large
Bridges
Caisson
Deep (10~40m)Many for Large
Bridges
Pneumatic CaissonOpen caisson Pnematic caisson
1 The construction period is irregular and The construction period is stable and
generally long can be predicted from previous records.
2 The preparation are relatively simple. Large mechanical equipment must be
The construction cost is lower compared used.Exerienced workers called
with the pneumatic caisson. "pneumatic caisson worker" are neces-
sary.The construction cost is high.
3 It loosens the surrounding ground. It rarely loosens the surrounding ground.
An accident can occur if water level in a However,rapid pressure loss and sub-
caisson falls far below the outside water sidence loosens the ground more than
level during underwater excavation. anticipated.
4 The construction depth can be larger Worker must work under high pressure.
than that of the pneumatic caisson if sur- Since the maximum limit is 3.5 Kgf/cm2
rounding friction can be decrease. the maximum depth is generally 35m
below the ground water level.
5 The foundation bottom can be confirmed.
A loading test is possible.
Obstacles can be remove easily.Water
and sendiments can be easily used for
setting load.
Comparison of construction methods
Steel Pipe Sheet Pile
Deep (20~60m)Ready-made PileMany for Bridges
over deep Rivers
Diaphragm (Slurry) Wall
Deep (20m~60m)Similar to CaissonSeldom but for large
load
How do we selectthe FOUNDATION TYPE?
1. Bridge and Span Length
2. Type, Scale and Dimension of Superstructure and Substructure
3. Investigation of Natural Conditions(Climate, Hydrology, SOIL, Geography)
4. Investigation of Site for Construction Method
Pile Foundation
The purpose of pile foundation is to transmit the load of the structurethrough soil strata which have a poor bearing capacity. Such as
• Compact sand or hard stratum underlying softer layer of sand or clayor any other soft material.
• Clayed soil with soft stratum overlying firm layer where the settlementof the soft stratum under open foundation is likely to be high.
• Dense or stiff soil overlying soft clay , where open foundation cannotbe spaced close enough for reducing the pressure transmitted to thesoft layer.
• Soft and thick alternating layers of clay and sand.• Sandy strata with standing water or high water table likely to cause in
difficulty excavation.• Upper soil strata are compressible or weak• Footing cannot transmit inclined horizontal or uplift forces.• Future excavation may be adjacent to be structure.• Expensive or collapsible soils extend for a considerable depth.
It may be contact with boom
Not clear from guide beam
So we cutt off here
INSERTING OF STAND PIPE
Vibrohamer
Guide BeamWorking Barge
Stand Pipe
Guide BeamWorking Barge
Stiffener Ring with welded joint
That we have already cutt off recently
Lapping Of Stand Pipe
Guide BeamWorking Barge
INSERTING STAND PIPE ON
GROUND
Center Line Of Crane
45Deg Of Earth Pressure Line
WrongRight
At Least 5 Meter
End of stand pipe must be exceed the earth pressure line which is 45
degree from the crane center.
45
Stand Pipe And Vibrohammer1. Diameter of stand pipe should be larger approaximately 15 cm larger
than pile diameter.
2. Length of stand pipe should be determined depending upon the depth of
insertion and the height of projection of pipe above the ground after
examining the soil condition and ground water level.
3. Thickness of wall of stand pipe should be determined by considering the
pile diameter, length and stresses or impacts during inserting or pull-out.
Also, stiffening or reinforcing of head portion of pipe will be desirable
4. Vibrohammer or hydraulic jack are used for inserting and pulling-out of
the stand pipe.Vibrohammer are most commonly used in Myanmar.
Less Than 1000 To 1600 To 2100 To
1000 1500 2000 3200
Machine Used
Vibrohammer 12 16 19 22
Jack 16 19 22 25
Relation Between Out Side Diameter And Wall Thickness Of Stand Pipe ( In mm )
Stand Pipe ရ ကျ ခငျ
• Standpipe က ေျရခ နျ ဖငျ Yမ ဥျ မတရရန Crane boom ျ ဖငျ ခ နေျပ ရမည။
• Standpipe က Vibro-hammer ျ ဖငျ YY တညျ မတေျအာငရ ကရမည။
• Standpipe က water level ထ နျ ရနျျ ငျ ေအပေေျ မလႊျာမ ာ မ ပ ရန
ရ ကရျ ခငျ ျ ဖစသည။
• Standpipe ရ႕ထ ပ R.L သည water level ထက ၂မတာ အနညျ ဆျျ ျ မငျ ရပါမည။
• Underground water level သည Bed water level ျျ ငျ သ ေပေ၀ ပါက bed water
level ေျအာကေျရာကေျအာင ရ ကေျပ ရမည။ ေျ၀ လ င ေျျ မ၀ငအနညျ ဆျျ
၃မတာရ ျ ရမည။
• Standpipe က ေျရထရ ကလ င ေျအာကပါအတ ငျ တတကခ ကရပါမည။
– Water Depth = 10m
– Standpipe Height over water level = 2m
– ေျျ မ၀ငအနက = 1/3(10+2) = 4m
– Total Standpipe Length = 10 + 2 + 4 = 16m
Excavation Drilling rig(RT3S)တ စက ေျရခ နညေရအာင ျ ပလပျ ပ လ င Crane တတငတ ပငငပါ။
Kelly bar က တ စကကတ ငတ ပငငပါ။ Kelly bar သည Telescopic ပျစျ ဖစျ ပ 12m သ ႕မဟတ
15m ေျလ ဆကပါသည။ 12m Kelly bar က သျျ ပါက 40m အနကထ တ န ငပါသည။ 15m Kelly
bar က အသျျ ျ ပပါက 50m အနကထ တ န ငသည။ သ ေ႕သာျ 50mေျက ာျတလနပါက
RCD(reversed circulation drilling method) က အသျျ ျ ပရမည။
Bucket က Kelly bar ထ ပပတ ငတပပါ။ တတငျ က တ ရာတတင တညျ မတေျအာငတတ ရမည။
တတငျ တ ရာတတင တတငျ အတတငျ ရ ျ Bentonite water level သည water level(or)ground
water level ထက 2m ျ မင ျရမည။
Bucket ငါ ခခကတ တ ျ ပ လ င အနက ၾက ျ ဖငျ ခ ပ တ ငျ ေျပ ရမည။ Sounding depth
တ ငျ ရာ တတင တတငျ ပတခ ာလည လ ညျ ျတ ငျ ပါ။ တ တထကကသ ာ ေျသာ ေျျ မစာမ ာ အစာ
Bentonite ရညျ ဖည ျ ေျပ ပါ။
Bentonite ရ specific gravity သည 1.02 မ 1.09အတတငျ ရ ျ ရမည။ ေျျ မနမ နာအာ
2mျ ခာ တစခါ စယ ပါ။ ရရ ျ လာေျသာ ေျျ မနမ နာျ င ျ ေျျ မသာ စမျ သပခ ကအရ
ေျဖာျျ ပထာ ေျသာျ ေျျ မအလႊျာ အမ အစာ တ မတ စစေျဆ ပါ။ မတ လ င အန ကပ
ၾက ၾကပသတထတငျ ပပါ။ ေျနာကင ျျ အလႊျာျ က အထ သတ ျ ပရပါမည။
ျ ပ စ လ ပ ငတငျ အတတငျ Bentonite level က မ တသ ာ ပါ။ တတငျ ျ ပ လ င Bentonite level
က ဆငျ ပါမည။ ထ ေ႕ၾကာငျ bentonite အရည အလ ငအ မနျ ဖညျ တငျ ပါ။
Sample For Profile Of Borehole
RT3s Drilling Rig
Stand pipe
When contact the trigger of bucket with frame
of R.T 3,which suddenly open shutter.So
deposal materials are running out.
Purpose Of Bentonite• Bentonite Water
– The most economic system a bore-hole open while drilling is progress and for casting apile involves the use of a fluid, the drilling mud, oppose:
• The pressure of outside water• The earth pressure into the section.Bentonite is a kind of chemical, which are including-
Mg Ca,Al2 O3 ,Si O2,H2OSome time we use C.M.C, if the soil condition is very fine and collapsed.A good drilling mud should be mixed such that the percentage of bentonite is from 5%
to8 % (of water),But it greatly depends on the quality and characteristics of the bentoniteavailable.
– Bentonite water create the bentonite cake on the surface of wall of hole when it iscontacted to sandy soil. Water head and properties of bentonite water ,which are directlyrelated to prevention of collapse of wall of hole and to discharge of excavated material.Bentonite water that circulates during excavation. Specific gravity is from 1.02 to 1.09.
– Bentonite ရ႕ Specific gravity သည 1.02 မ 1.09 ထ ရ ျ ျ ပ ေျရရ႕ Specific
gravity သည 1.0 ျ ဖစသျ ဖငျ ျ ပငပေမ ရက တတငျ တ ေျနစဥာတကယထ ာ သည။
– Concrete ရ႕ Specific gravity သည 2.37ျ ဖစသျ ဖငျ concrete တသနျ ေျလာငျ လ င
bentonite အရညေ ာ က အလ ေအလ ာက တတနျ ဖယနျ ျငသည။
Betonite Betonite Specific
kg/m3 of mud % Gravity sec. sand %
nil 0 1.000 27 1.0 Clay
20 2 1.010 28 1.1 Clay
30 3 1.020 30 2.2 Clay
40 4 1.025 35 3.7 Clay
50 5 1.035 40 6.6 Clayed sand
60 6 1.035 40 12.0 Clayed sand
70 7 1.040 45 19.0 Clayed sand
80 8 1.045 55 35.0 Sand
90 9 1.070 60 68.0 Sand
100 10 1.075 70 92.0 Sand
ViscosityRemark
Properties Of Bentonite
Bentonite
Bentonite Cake
Soil Particle
-Bentonite level in the hole must be more than 2 meter above the water level or under ground water level.
Bentonate water create the bentonite cake on the surface of wall of hole when it is contacted to sandy soil.
Water head and properties of bentonite water,which are directly related to prevention of collapse of wall of
hole and to discharge of excavated material. Bentonite water that circulates during excavation. Specific
gravity is from 1.02 to 1.06.
. Hydrostatic pressure
0.2 Kg/cm2
Hydrostatic pressure
0.2 Kg/cm2
.
Hydrostatic
Pressure
Over
0.2 Kg/cm2
Ground water level
Ground levelWater level
Over 2 m
Bentonite
Bentonite Cake
Soil Particle
Test For Specific Gravity Of Bentonite
ပထမဥ ခစာ မ နပျျ တစခထတတင အလညေလေအပေသ ႕ဆချထတ
လ ႕ေရသာ မ နျ ပာ တစျ ပာ ချ ပ တစဖကကတ င သကန၊ တစဖကကတ င
Bentonite အရညတစနစထညျ ပါ။
-4if;aemufrSefjym;udktay:odkYjznf;nif;pGmrwifvdkufyg/
ထ အခါ ပျ(၁)တတငျ ပထာ သက သ ႕ ပ က မတသာ လ င Bentonite ရ႕ Specific gravity
သည ေအကာငျ ဆျျ ျ ဖစသည။ ပျ(၂)က သ ႕အနညျ ငယေျလ ာ က တသာ လ င
သငျ ေျတာျေျသ ေျသာျလညျ ပျ(၃)က သ ႕ လျျ ေ၀လ ာ က တသာ လ င ေျရထသ ႕
bentonite ထပေေျရာစပေျပ ရမညျ ဖ ပ ပျ(၁) က သ ႕ ေအနအထာ ျ ဖစမျ ဖစ
ျ ပနညစမျ သပေျပ ရမည။
yHk 1
yHk 2
yHk 3
Drilling Rig R.T 3 S
Kelly Bar
Stand PipeGuide Beam
Drilling Rig R.T 3 S
Kelly Bar
Stand Pipe
Guide BeamBentonite Supply Hose
ေျရလကညတင Bored Pile တ ေျနပျ
Working Barge
ဒတ ယပ ငျ ဆကရန
• Desanding
• Rebar Cage
• Concreting
• Tremie Pipe
• Pullout of Standpipe
• RCD
• Airlift