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