Types of Foundation Made by Weisiong

8/20/2019 Types of Foundation Made by Weisiong

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TYPES OF FOUNDATION MADE BY WEISIONG

Contents

Chapter Subject Page

1 Shallow foundation 1

2 Deep Foundation 17

Reference 33

TYPES OF FOUNDATION

a) Shallow Foundation Syte!

i) Spread Foundation

ii) "at # Raft Foundation

b) Deep Foundation Syte!

i) Pile iii) Diaphragha! wall

ii) Pile wall i$) Caion


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Chapter 1

Shallow fon!at"on

Intro!#t"on

%hoe which tranfer the load to uboil at a point near to the ground floor of the

building uch a trip and raft& ' hallow foundation i a type of foundation which tranfer

building load to the earth $ery near the urface( rather than to a uburface layer or a range of

depth a doe a deep foundation& Shallow foundation include pread footing foundation( raft

foundation nown a !at*lab foundation( lab*on*grade foundation( trip foundation(

buoyancy foundation( pad foundation( rubble trench foundation( and earth bag foundation&

%hee foundation i according to +S ,--. / 10,&

Shallow foundation are taen to be thoe where the depth below finihed ground le$el i

le than 3 ! and include trip( pad and raft foundation& Shallow foundation where the depth

breadth ratio i high !ay need to be deigned a deep foundation & Shallow foundation are

thoe foundation that ha$e a depth*of*e!bed!ent*to*width ratio of approi!ately le than

four&

Shallow foundation are thoe founded near to the finihed ground urface generally

where the founding depth 4Df ) i le than the width of the footing and le than 3!& %hee are

not trict rule( but !erely guideline/ baically( if urface loading or other urface condition

will affect the bearing capacity of a foundation it i 5hallow5& Shallow foundation 4o!eti!e

called 5pread footing5) include pad 45iolated footing5)( trip footing and raft&

Shallow foundation are ued when urface oil are ufficiently trong and tiff to upport the

i!poed load they are generally unuitable in wea or highly co!preible oil( uch a

poorly*co!pacted fill( peat( recent lacutrine and allu$ial depoit( etc&

Advantage of using shallow foundation


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i& Cot i affordable&

ii& Contruction procedure i i!ple&

iii& "aterial i !otly concrete&i$& 6abour doe not need epertie&

Disadvantages of using shallow foundation

i& Settle!ent&

ii& 6i!it capacity oil tructure&

iii& rregular ground urface for ea!ple lope and retaining wall&

i$& Foundation ubjected to pullout( torion and !o!ent&

Foot"n$ Fon!at"ons

' footing i that part of a tructure which er$e to tran!it the weight of the tructure to

the natural uboil& ' footing that upport a ingle colu!n i an iolated footing or a preadfooting( one that upport a group of colu!n i a co!bined footing and one that upport a wall i

a continuou or trip footing& %he depth of footing( Df( i the $ertical ditance between the bae

of the footing and the ground urface& f Df i le width of the footing it i called a hallowfooting& %he beha$iour of hallow continuou footing will be preented firt&

COMBINATION FOOTINGS

Co!bination( or co!bined( footing are i!ilar to iolated pread footing ecept that theyupport two or !ore colu!n and are rectangular or trape8oidal in hape 4Figure 2*9)& %hey are

pri!arily ued when the colu!n pacing i non*unifor! 4+owle( 100) or when iolated pread

footing beco!e o cloely paced that a co!bination footing i i!pler to for! and contruct& nthe cae of bridge abut!ent( an ea!ple of a co!bination footing i the o*called :pill*

through; type abut!ent 4Figure 2*)& %hi configuration wa ued during o!e of the initial

contruction of the ntertate freeway on new align!ent where pread footing could be

founded on co!petent nati$e oil& Spill*through abut!ent are alo ued at trea! croing to!ae ure foundation are below the cour le$el of the trea!&

Due to the fra!e action that de$elop with co!bination footing( they can be ued to reit large

o$erturning or rotational !o!ent in the longitudinal direction of the colu!n row&

%here are a nu!ber of approache for deigning and contructing co!bined footing& %he choice

depend on the a$ailable pace( load ditribution a!ong the colu!n upported by the footing(

$ariation of oil propertie upporting the footing and econo!ic&


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%ype of Co!bined Footing/

i& Rectangular Co!bined Footing

ii& %rape8oidal Co!bined Footing

iii& Cantile$er Footing

i$& "at Foundation 4 raft foundation )

Ult"%ate Bear"n$ Capa#"t&

%er8aghi 410.3 ) firt publihed an approi!ate !ethod of co!puting ulti!ate bearing

capacity of oil& +& f Df ? +

the error becaue of neglecting hear reitance along ''' and ++' beco!e appreciable&i$& %he footing i continuou& %hi i!plifie the analyi becaue the proble! beco!e two

di!enional& For iolated and pread footing a correction factor baed on eperience ha

been reco!!ended by %er8aghi&

Criteria of Satifactory 'ction of a Footing

' footing !ut atify two general re=uire!ent which are a follow/

i& %he oil upporting the footing !ut be afe againt hear failure& 'n ade=uate factor of

afety i pro$ided while aigning allowable load to a footing&

ii& %he footing !ut not ettle !ore than a pecified a!ount&

%he uual procedure of deign of a footing conit of the following /

i& Select a uitable width and depth for the footing&ii& Deter!ine the allowable oil preure for !ai!u! ettle!ent of the footing&

iii& Deter!ine the ulti!ate bearing capacity of the oil&

i$& Deter!ine allowable oil preure by applying a uitable factor of afety to ulti!ate

bearing capacity&


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Test Cube

Des"$n of Foot"n$s

6oad "ai!u! 4@ewton) 4P)

Co%press"on stren$th ' ((((((((((((((((((((((((((((((((((( (((

+ric width urface 4P6) 4')

Depth of Foot"n$

%he depth to which foundation hould be carried depend upon the following factor /

i& %he ecuring of ade=uate bearing capacity&

ii& n the cae of clayey oil( depth of 8one in which the hrinage and welling due to

eaonal weather change are liely to caue appreciable !o$e!ent&

iii& n fine and and ilt( depth of 8one up to which frot trouble !ay be encountered&

i$& %he depth up to which eca$ation are liely in future in cloe proi!ity&

ndian Standard Code of Practice( pro$ide for a !ini!u! depth 9- c! below the

natural ground&

Subject to the re=uire!ent of the code( the footing i ordinarily located at the highet

point( where ade=uate bearing capacity i obtained& n o!e intance if an epecially fir!

layer i a$ailable at a greater depth( it !ay be !ore econo!ical to etablih the footing at a

lower ele$ation becaue the area re=uired for the footing would be !aller&

SP)EAD FOOTING FOUNDATION

a& 'lo nown a a footer or footing

b& tA an enlarge!ent at the botto! of a colu!n#

c& bearing wall that pread the applied tructural load o$er a ufficiently large oil

area&


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d& Bach colu!n each bearing wall ha it own pread footing( o each tructure !ay

include do8en of indi$idual footing&

SP)EAD FOUNDATION

& %he foundation conit of concrete lab located under each tructural colu!n and a

continuou lab under load*bearing wall&

& For the pread foundation yte! the tructural load i literally pread out o$er a broad

area under the building

& "ot co!!on type of foundation ued due to their low cot eae of contruction&

& "ot often ued in !all to !ediu! i8e tructure with !oderate to good oil condition

& Spread footing !ay be built in different hape i8e to acco!!odate indi$idual

need uch a the following/

a) S=uare Spread Footing # S=uare Footing

b) Rectangular Spread Footing

c) Circular Spread Footing

d) Continuou Spread Footing

e) Co!bined Footing

f) Ring Spread Footing


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a) S=uare Spread Footing # Pad Foundation

* upport a ingle centrally located colu!n

* ue concrete !i 1/2/. and reinforce!ent

* the reinforce!ent in both ae are to

reit#carry tenion load&

PAD FOUNDATION

b) Rectangular Spread Footing

* Eeful when obtruction pre$ent

contruction of a =uare footing with a

ufficiently large bae area and when

large !o!ent load are preent

c) Circular Spread Footing

* are round in plan $iew

* !ot fre=uently ued a foundation for

light tandard( flagpole and power


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tran!iion line&

d)Continuou Spread Footing # Strip Foundation

* Eed to upport bearing wall

e) Co!bined Footing

* upport !ore than one colu!n

* ueful when colu!n are located too cloe

together for each to ha$e it own footing

f) Ring Spread Footing

* continuou footing that ha$e been wrapped into a

circle

* co!!only ued to upport the wall abo$e*ground

circular torage tan&

* %he content of thee tan are pread e$enly

acro the total bae area and thi weight i probably

greater that the tan itelf

* %herefore the geotechnical analye of tan uually

treat the! a circular foundation with dia!eter

e=ual to the dia!eter of the tan&


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Fa#tors of Safet&

For afety againt bearing capacity failure a factor of afety of 3 i reco!!ended under

the probable !ai!u! load& For tructure of !inor i!portance and in uboil of unifor!

character whoe propertie are $ery well nown( a !aller factor of afety !ay be ued& ' factor

of afety of three i co!parable with the $alue co!!only ued for the deign of upertructure&

Settle%ent

'ccording to ndian Standard Code of Practice referred to pre$iouly( for !ot of the

ordinary concrete tructure( uch a office building( flat and factorie( differential ettle!ent

!ay be per!iible uch that the angular ditortion of the fra!e of the building doe not eceed

1#29- nor!ally and 1#1--- where it i particularly deired to a$oid any ind of da!age& %able

below how the li!iting total ettle!ent of iolated footing( a reco!!ended in the &S code&

Soil %otal Settle!ent

@on Cohei$e .&- c!

Cohei$e &9 c!

%able 1 Pre!iible Settle!ent of olated Footing

Gross an! net loa!

%he total load on the footing including it own weight i gro load( and the unit load i

the gra intenity of loading& f howe$er( the weight of the oil eca$ated for contructing the

footing i deducted fro! the gro load( it i called the net load and the unit load i then the net

intenity of loading&

Net lt"%ate *ear"n$ #apa#"t&


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t ha been defined a preure at the bae of footing in ece of that at the a!e le$el

due to urrounding urcharge& %he ue of net bearing capacity i o!eti!e !ore con$enient in

deign&

%hu =a 4 net ) =a G yDf

c@c H I y+@y H yDf 4@=*1)

'ccording to %er8aghiA e=uation&

Settle%ent

T&pes of Fon!at"on Settle%ent

%he ettle!ent of a foundation conit of two part& %hey are

i& Blatic ettle!ent 4 Se )

ii& Conolidation ettle!ent 4 Sc )

Blatic ettle!ent i caued by the elatic defor!ation of dry oil and of !oit and aturated

oil without any change in !oiture content& Conolidation di$ide into two group na!ely

pri!ary conolidation and econdary conolidation& Pri!ary conolidation i the reult of a

$olu!e change in aturated cohei$e oil becaue of the epulion of water that occupie the

$oid pace& Secondary conolidation ettle!ent i ober$ed in aturated cohei$e oil and i the

reult of the platic adjut!ent of oil fabric& t follow the pri!ary conolidation ettle!ent

under contant effecti$e tre&


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Figure 1&1 Blatic ettle!ent profile&

)aft Fon!at"on

)AFT FOUNDATION

' foundation yte! in which eentially the entire building i placed on a large

continuou footing&

t i a flat concrete lab( hea$ily reinforced with teel( which carrie the downward load

of the indi$idual colu!n or wall&

Raft foundation are ued to pread the load fro! a tructure o$er a large area( nor!ally

the entire area of the tructure&

MAT+)AFT FOUNDATION


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t i nor!ally conit of a concrete lab

which etend o$er the entire loaded area&

t !ay be tiffened by rib or bea!

incorporated into the foundation&

Raft foundation ha$e the ad$antage of reducing differential ettle!ent a the concrete

lab reit differential !o$e!ent between loading poition&

%hey are often needed on oft or looe oil with low bearing capacity a they can pread

the load o$er a larger area&

Raft foundation are ued to pread the load fro! a tructure o$er a large area( nor!ally the

entire area of the tructure& %hey are ued when colu!n load or other tructural load are cloe

together and indi$idual pad foundation would interact&

' raft foundation nor!ally conit of a concrete lab which etend o$er the entire loaded

area& t !ay be tiffened by rib or bea! incorporated into the foundation&

Raft foundation ha$e the ad$antage of reducing differential ettle!ent a the concrete lab

reit differential !o$e!ent between loading poition& %hey are often needed on oft or looe

oil with low bearing capacity a they can pread the load o$er a larger area&

Raft foundation are shallow foundation, is a combined footing that may cover

the entire area under a structure supporting several columns and walls. Raft

foundation are sometimes preferred for soils that have low load-bearing capacities

but that will have to support high column and wall loads. Under some conditions,

spread footings would have to cover more than half the building area, and raft

foundations might be more economical. Raft foundation are ued to ditribute hea$y


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colu!n and wall load acro the entire building area( to lower the contact preure co!pared to

con$entional pread footing&

Raft foundation can be contructed near the ground urface( or at the botto! of

bae!ent& n high*rie building( raft*lab foundation can be e$eral !eter thic( with

eteni$e reinforcing to enure relati$ely unifor! load tranfer& This type of foundation is

often used on poor soils of lightly loaded buildings and is capable of accommodating

small settlement of soil. n poor soil the upper crust of soil !"#$-%$$mm&is often

stier than the lower subsoil and to build a light raft on this crust is usually better

then penetrating it with a strip foundation. f the building loads or the allowable soil

pressure low and the area of isolated footings e(ceeds about one half the area of

the building it may be economical to provide a raft foundation. f the centre of

gravity of the loads coincides with the centre of the raft, the distribution below the

raft is usually assumed to be uniform. t has been shown that the pressure

distribution below the base of a raft is generally not uniform. This may result in

increased moments than those computed on the assumption of uniform pressure

distribution.

f a raft foundation i located at uch a depth that the unit load of the upertructure and

the raft e=ual the weight of the oil re!o$ed( 4 yDf )( it i called floating foundation& n thi cae

there i no increae in the preure intenity on the oil under the raft( and there i no proble! of

tability& Settle!ent are retricted to the etent of any welling which !ight ha$e taen place

after eca$ation& %he floating foundation i ueful in e$ery wea oil& Se$eral type of raft

foundation are currently ued& So!e of the co!!on type are the following /

i& Flat plate& %he raft foundation i unifor! thicne&

ii& Flat plate thicened under colu!n&

iii& +ea! and lab& %he bea! run both way( and the colu!n are located at the

interection of the bea!&

i$& Flat plate with pedetal&

$& Slab with bae!ent wall a a part of the raft foundation& %he wall act a tiffener for

the raft foundation&


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Raft foundations may be supported by piles. The piles help in reducing thesettlement of a structure built over highly compressible soil. )here the water tableis high, raft foundations are often placed over piles to control buoyancy.

Chapter ,

Deep Fon!at"on

Intro!#t"on

Btend e$eral do8en feet below the building

a) Pile

b) Pier

c) Caion

d) Co!penated Foundation

Deep foundation are thoe founding too deeply below the finihed ground urface for

their bae bearing capacity to be affected by urface condition( thi i uually at depth ?3 !

below finihed ground le$el& %hey include pile( pier and caion or co!penated foundation

uing deep bae!ent and alo deep pad or trip foundation& Deep foundation can be ued to

tranfer the loading to a deeper( !ore co!petent trata at depth if unuitable oil are preent

near the urface&

%hoe which tranfer the load to a uboil o!e ditance below the ground floor of the building uch a pile& ' deep foundation i a type of foundation ditinguihed fro! hallow

foundation by the depth they are e!bedded into the ground& %hey are either end*bearing if they

etend all of the way to roc or hard oil( or they are friction pile if they are !ainly upported

by friction along the ide( although friction pile alo uually de$elop o!e end upport& %i!ber

pile are dri$en top down to tae ad$antage of their taper for increaing friction( and a taper often


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i incorporated of their taper for increaing friction( and a taper often i incorporated into

concrete pile& Co!paction pile are dri$en into looe an to denify it and increae it bearing

capacity& "odern pile are wood(teel(concrete( or co!poite if they are co!poed of !ore than

one !aterial& 'n ea!ple of a co!poite pile i when a wood pile ection i ued under a

groundwater table where it i preer$ed by reducing condition( and i connected to a concrete

ection that etend through aerobic urrounding abo$e the water table&%here are !any reaon

a geotechnical engineer would reco!!end a deep foundation o$er a hallow foundation( but

o!e of the co!!on reaon are $ery large deign load( a poor oil at hallow depth( or ite

contraint 4lie property line)& %here are different ter! ued to decribe different type of deep

foundation including the pile 4which i analogou to a pole)( the pier 4which i analogou to a

colu!n)( drilled haft( and caion& Pile are generally dri$en into the ground in itu other

deep foundation are typically put in place uing eca$ation and drilling& Jherea pile are

dri$en or can be jaced into the ground( pier are large*dia!eter upport that are placed in pre*

bored hole& Caion are large tube ued for contruction below water( a in ri$er( and !ay be

preuri8ed to eep water out& Caion foundation o!eti!e i applied to bored pier( and pier

alo are o!eti!e called haft or pile( leading to o!e deep confuion&

%he na!ing con$ention !ay $ary between engineering dicipline and fir!& Deep

foundation can be !ade out of ti!ber( teel( reinforced concrete and pretreed concrete& %hee

foundation i according to +S ,--. / 10, which !ean !ore than 3 !eter&


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Figure 2&1 Deep(inter!ediate( and hallow foundation&

T&pes of !eep fon!at"on

Deep foundation !ay be claified a follow&

i& Deep pad or trip footing&

ii& +ae!ent or hollow boe 4co!penated foundation)&iii& Caion& %hee !ay be open well caion or pneu!atic caion&

i$& Cylinder and pier& %hee !ay be eca$ated in the dry by hand( by !echanical !ean or(

in the wet by !echanical !ean including boring and lurry wall techni=ue&$& Pile&

$i& Peripheral wall& Concrete wall contructed in a lurry*filled trench or a contiguou

bored pile( a well a being ued a bae!ent or retaining wall( !ay alo carry $erticalload in conjunction with their retaining function&

$ii& "ied foundation& %hee !ay be a co!bination of any of a) to f)&

$iii& Kround i!pro$e!ent or replace!ent& Jhere the ground doe not ha$e ade=uate bearing

characteritic and tability( conideration !ay be gi$en to general or local i!pro$e!entof the bearing characteritic or to replace!ent of the ground in depth& t !ay then be

poible to ue a hallow foundation or a cheaper type of deep foundation&

C&l"n!ers an! p"ers


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PIE)S

tA a $ertical bridge upport&

tA a foundation for carrying a hea$y tructural load which i contructed in ite in a

deep eca$ation&

Pier are foundation for carrying a hea$y tructural load which i contructed initu in adeep eca$ation&

Cylinder are eentially !all open well caion co!priing ingle cell which are ofcircular cro ection& 4%he ter! pier i o!eti!e ued for i!ilar foundation of circular or

other haped cro ection&) %he ditinction between cylinder and caion i one of i8e and i

necearily arbitrary& +ecaue of their !aller i8e( cylinder lend the!el$e !ore readily to theue of precat ele!ent in their contruction& For ea!ple( co!plete precat ring !ay be added

at the top a the cylinder i being un&Cylinder are o!eti!e contructed by the !ethod in which the ground beneath the

lower edge of the cylinder o far contructed i re!o$ed and a further ring lowered in ection iintalled below it( and o on& %hi !ethod i liely to be e!ployed only in appropriate ground

condition in the dry( or where pu!ping( grouting or free8ing i practicable& 'nother !ethod i to

eca$ate to a !all depth with an unupported face( then to place for!wor( behind whichconcrete i placed to upport the oil& +elow the water table( !ethod of ining cylinder are

uually i!ilar to thoe ued for open well caion& Sining cylinder 4or large bored pile) by

!echanical drilling or grabbing !ethod ha largely upereded hand !ethod of eca$ation&Cylinder are often filled with concrete and are o!eti!e reinforced&

Compensated foundations

Co!penated foundation are deep foundation in which the relief of tre due to eca$ation i

approi!ately balanced by the applied tre due to the foundation& %he net tre applied i

therefore $ery !all& ' co!penated foundation nor!ally co!prie a deep bae!ent&

Per"pheral walls


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Jith uch wall( for!ed by eca$ating under a lurry( care i neceary to enure that

lurry i not trapped between the concrete and the bae of the eca$ation& Diaphrag! wall arerelati$ely lender tructural !e!ber and they hould be capable of withtanding earth preure

and hydrotatic preure at each tage in the e=uence of eca$ation and upport by anchorage

and by te!porary and per!anent horing&

't the final tage of eca$ation of a ubtructure with peripheral diaphrag! wall( the

wall are retrained fro! inward !o$e!ent by the pai$e reitance of the oil below the baeof the eca$ation until uch ti!e a the floor lab of the ubtructure i placed& %he depth of

penetration of the peripheral wall hould be ade=uate to !obili8e the re=uired pai$e reitance

of the oil and alo to pre$ent eroion by eepage of water beneath the toe of the wall into the

eca$ation& Jhere inclined ground anchor are ued to pro$ide upport againt eternal preure( the thicne of the wall at the toe hould be ufficient to pre$ent ecei$e ettle!ent

due to force induced by the $ertical co!ponent of the anchor tre&

%he thicne of the wall at the toe hould alo be ufficient to pre$ent ecei$eettle!ent reulting fro! $ertical loading applied to the cret or inter!ediate le$el in a wall

fro! floor or colu!n& Diaphrag! wall techni=ue are ued to for! load bearing foundationtructure 4o!eti!e referred to a barrette) which !ay be of rectangular( crucifor!( hollow

bo or other plan hape 4Corbett et al& 107.)&

M"-e! fon!at"ons on non(n"for% s"tes

Jhen ite in$etigation indicate that ground condition are not unifor!( it i i!portantto pro$ide the type and i8e of foundation appropriate to the ground condition eiting on the

ite( and it hould be recogni8ed that the etent of ground $ariation i not alway fully re$ealed

in a ite in$etigation& Ln any ite further infor!ation about ground condition beco!ea$ailable during contruction( and on a non*unifor! ite infor!ation can often !ae change in

foundation neceary& ' typical ea!ple i a change in le$el of the ground*bearing tratu!(

re$ealed during foundation contruction( leading to re$ied reinforce!ent re=uire!ent and proble! in coping with groundwater( with cone=uent delay on ite& ' for! of contruction

which can eaily be $aried to uit the local ground condition ha ad$antage in uch a cae&

Con$erely( if the choice of foundation i of a ind that cannot be eaily !odified to uit

$ariation in ground condition( then a !ore eniti$e ite in$etigation would be appropriate&

' nowledge of pre$iou ite hitory and ite geology are helpful in pro$iding a ene of

the etent of $ariation of ground condition that !ay be epected& Jhen ground condition arenot unifor!( the ue of !ore than one type of foundation could reult in greater econo!y& For

ea!ple( if an old buried ri$er channel croe a ite where a atifactory bearing tratu! eit

elewhere near ground le$el( it !ay be econo!ical to ue hallow foundation co!bined with pile in the deeper part& Jhen uing !ied foundation( pecial attention will need to be paid to

the effect on the tructure( particularly where differential ettle!ent can occur& f the foundation

and the upporting ground are looed at a one entity( a they hould be( it will be een that any

foundation !ay beha$e in a co!ple way& n particular( differential ettle!ent !ay occur for a


19/31


20/31

Pile are relati$ely long( lender !e!ber that tran!it foundation load through oil trata

of low bearing capacity to deeper oil or roc trata ha$ing a high bearing capacity& %hey are

ued when for econo!ic( contructional or oil condition conideration it i deirable to tran!it

load to trata beyond the practical reach of hallow foundation& n addition to upporting

tructure( pile are alo ued to anchor tructure againt uplift force and to ait tructure in

reiting lateral and o$erturning force&

Pile are tructural !e!ber that are !ade of teel(concrete( or ti!ber& %hey are ued to build

pile foundation( which are deep and which cot !ore than hallow foundation& Depite the

cot( the ue of pile often i neceary to enure tructural afety& ' pile can be looely defined

a a colu!n inerted in the ground to tran!it the tructural load to a lower uboil& Pile ha$e

been ued in contact two hundred year ago and until the twentieth century were in$ariably of

dri$en ti!ber& %he following lit identifie o!e of the condition that re=uire pile foundation

4 eic( 1077 )

i& Jhen one or !ore upper oil layer are highly co!preible and to wea to upport the

load tran!itted by the upertructure( pile are ued to tran!it the load to underlying

bedroc or a tronger oil layer& Jhen bedroc i not encountered at a reaonable depth

below the ground urface( pile are ued to tran!it the tructural load to the oil

gradually& %he reitance to the applied tructural load i derie$ed !ainly fro! the

frictional reitance de$eloped at the oil*pile interface&

ii& Jhen ubjected to hori8ontal force( pile foundation reit by bending( while till

upporting the $ertical load tran!itted by the upertructure& %hi type of ituation i

generally encountered in the deign and contruction of earth*retaining tructure and

foundation of tall tructure that are ubjected to high wind or to earth=uae force&

iii& n !any cae( epani$e and collapible oil !ay be preent at the ite of a propoedtructure& %hee oil !ay etend to a great depth below the ground urface& Bpani$e

oil well and hrin a their !oiture content increae and decreae( and the preure

of the welling can be coniderable& f hallow foundation are ued in uch

circu!tance( the tructure !ay uffer coniderable da!age&


21/31

which i where welling and hrining occur& Soil uch a loe are collapible in

nature& Jhen the !oiture content of thee oil increae( their tructure !ay brea

down& ' udden decreae in the $oid ratio of oil induce large ettle!ent of tructure

upported by hallow foundation& n uch cae( pile foundation !ay be ued in which

the pile are etended into table oil layer beyond the 8one where !oiture will change&

i$& %he foundation of o!e tructure( uch a tran!iion tower( offhore platfor!( and

bae!ent !at below the water table( are ubjected to uplifting force& Pile are

o!eti!e ued for thee foundation to reit the uplifting force&

$& +ridge abut!ent and pier are uually contructed o$er pile foundation to a$oid the lo

of bearing capacity that a hallow foundation !ight uffer becaue of oil eroion at the

ground urface&

'lthough nu!erou in$etigation( both theoretical and eperi!ental( ha$e been conducted

in the pat to predict the beha$ior and the load*bearing capacity of pile in granular and

cohei$e oil( the !echani! are not yet entirely undertood and !ay ne$er be& %he deign

and analyi of pile foundation !ay thu be conidered o!ewhat of an art a a reult of the

uncertaintie in$ol$ed in woring with o!e uboil condition&

%he !ain function of bearing pile i to tranfer the load to lower le$el of the ground whichare capable of utaining the load with an ade=uate factor of afety and without ettling at the

woring load by an a!ount detri!ental to the tructure that they upport& Pile deri$e their

carrying capacity fro! a co!bination of friction along their ide and end bearing at the pile point or bae& %he for!er i liely to predo!inate for pile in clay and ilt and where long

ocet are for!ed in oft roc& %he latter applie to pile ter!inating in a tratu! uch a

co!pact gra$el( hard clay or roc& Jhen friction pile are intalled in a deep depoit of fairlyunifor! conitency in order to tranfer the foundation preure to the lower le$el( they hould

be long enough to enure a ubtantial ad$antage o$er a hallow foundation& n thee

circu!tance it hould be borne in !ind that for the a!e uperficial area of pile urface( a few

long pile for!ing a piled foundation are !ore effecti$e and will upport the load with !aller ettle!ent than !any hort pile&

Pile hould be intalled to the precribed depth( reitance or et per blow withoutda!age to the pile haft or the bearing tratu! and record of the intallation proce hould be

!aintained& %he pile hould be able to carry their deign load without eceeding the

per!iible woring tree in the !aterial of the pile( but the tree during dri$ing !ayeceed thee& %he tree during pitching and handling hould be within the afe bending

tree precribed in the deign& %he load hould be applied concentrically with the ai of the

pile or the centre of gra$ity of the pile group& 'llowance hould be !ade in the deign for

inaccuracie in poitioning the pile( particularly for iolated ingle pile or pair of pile& Jhere


22/31

per!anent eccentric load ha$e to be carried( due allowance hould be !ade in the deign& n

certain ituation $ertical pile !ay be ubjected to hori8ontal or eccentric load& f the ground i

unable to reit the reultant force without ecei$e lateral !o$e!ent( additional reitancehould be pro$ided& %hi can be achie$ed by increaing the nu!ber of $ertical pile or increaing

their tiffne( by the ue of raing pile or ground bea! or by replacing the upper oil layer

with oil !ore capable of reiting hori8ontal force& Special conideration hould be gi$en toeffect uch a ground hea$e due to frot or the beha$iour of epani$e clay( te!perature

$ariation in the ground and alteration in groundwater le$el( in cae they are detri!ental to the

bearing capacity or effecti$ene of the pile& %e!perature change !ay alo affect the hori8ontaldi!enion of the upertructure( thereby ditorting the pile and cauing additional tree&

Figure 2&2/ Piling

Class"f"#at"on of P"les


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Pile !ay be claified by the way in which they tran!it their load to the uboil or by the

way they are for!ed& Pile !ay tran!it their load to a lower le$el by/

a. En! Bear"n$

%he haft of the pile act a colu!n carrying the load through the o$erlaying wea

uboil to fir! trata into which pile toe ha penetrated& %hi can be a roc trata or a layer of

the fir! and or gra$el which ha been co!pacted by the diplace!ent and $ibration

encountered during the dri$e&

Figure 2&2/ Friction Pile

*. Fr"#t"on

'ny type of foundation i!poe on the ground a preure which pread out to for! a

bulb of preure& f a uitable load bearing trata cannot be found at an acceptable le$el(

particularly in tiff clay oil( it i poible to ue a pile to carry thi bulb of preure to a

lower le$el where a higher bearing capacity i found& %he friction of floating pile i !ainly

upported by the adheion or the friction action of the oil around the peri!eter of the pile

haft&


24/31

Figure 2&3/ Bnd +earing Pile

T&pes of *ear"n$ p"les

%he claification of bearing pile i related to the effect on the oil& %here are two !ain

type/ diplace!ent pile and replace!ent pile&

a) D"pla#e%ent P"les

' diplace!ent pile i either dri$en( jacet ( $ibrated or crewed into the ground& %hi

ection diplace the oil outward and downward but the !aterial i not actually re!o$ed&

%here are two type of diplace!ent pile/ large diplace!ent pile which include all olid dri$en

pile and !all diplace!ent pile( in which $ery little oil i diplaced& %hi would include the

crewed pile and < pile&

*. )epla#e%ent P"les


25/31

Replace!ent pile !ay be claified a Supported or Enupported&n both cae a hole i

for!ed in the ground by o!e for! of cutting or boring tool and i then filled with reinforced

concrete& %he unupported hole will nor!ally re=uire a hort tube at the top to pre$ent debri

fro! falling into the concrete during placing& Support to hole !ay be pro$ided by !ean of

!ediu! or hea$y ectional caing( crewed together a boring proceed(or by !ean by a head

of drilling !ud 4uually bentonite upenion)&

T&pes Of P"le

Dr"/en P"les

a. T"%*er p"les

%i!ber pile are tree trun that ha$e had their branche and bar carefully tri!!ed off& %he

!ai!u! length of !ot ti!ber pile i 3- ft to 9ft& to =ualify for ue a a pile( the ti!ber

hould be traight( ound( and without any defect& %i!ber pile are uually =uare awn

hardwood or oftwood in length up to 12&---! in ection(with i8e ranging fro! 229 229

!! to --!! -- !! &"ot ti!ber pile are fitted with an iron or teel dri$ing hoe and ha$e

an iron ring around the head to pre$ent plitting due to dri$ing& 'lthough not particularly

co!!on they are ued in ea defence uch a groyne and o!eti!e a guide pile for large in

conjunction with teel heet piling& %he '!erican Society of Ci$il Bngineer :"anual of

Practice( @o& 17 4 1090 ) di$ided ti!ber pile into three clae /

i& Cla ' pile carry hea$y load& %he !ini!u! dia!eter of the butt hould be 1. in&

ii& Cla + pile are ued to carry !ediu! load& %he !ini!u! butt dia!eter hould be

12 to 13 in&

iii& Cla C pile are ued in te!porary contruction wor& %hey can be ued

per!anently for tructure when the entire pile i below the water table& %he

!ini!u! butt dia!eter hould be 12 in&

n any cae( a pile tip hould not ha$e a dia!eter le tan in& %i!ber pile cannot withtand

hard dri$ing tre therefore( the pile capacity i generally li!ited& Steel hoe !ay be ued to

a$oid da!age at the pile tip 4 botto! )& %he top of ti!ber pile !ay alo be da!aged during the

dri$ing operation& %he cruhing of the wooden fiber caued by the i!pact of the ha!!er i

referred to a broo!ing& %o a$oid da!age to the top of the pile( a !etal band or a cap !ay be


26/31


27/31

%he pile are !ade fro! e!pa( a ind of broadleaf tree& %he cro ectional area of the

pile i 9 inche by 9 inche and i inche by inche(and the pile i 2- to 2. feet long& %he

per!iible degree of bow or wrap of the pile within 2- feet long i 1I inche fro! a traight

ai through the pile& %he per!iible degree of wrap of a pile !ore than 2- feet long i 2 inche&

Deign woring ad of 9 inche by 9 inche pile an d inche by inche pile are the 19

ton#pile and the 2- tonne repecti$ely&

!. Co%pos"te P"les

%he upper and lower portion of co!poite pile are !ade of different !aterial& For

ea!ple( co!poite pile !ay be !ade of teel and concrete or ti!ber and concrete teel*and*

concrete pile conit of a lower portion of teel and upper portion of cat*in*place concrete& %hi

type of pile i ued when the length of the pile re=uired for ade=uate bearing eceed the

capacity of i!ple cat*in*place concrete pile& %i!ber*and*concrete pile uually conit of a

lower portion of ti!ber pile below the per!anent water table and an upper portion of concrete&

n any cae( for!ing proper joint between two dii!ilar !aterial i difficult( and for that

reaon( co!poite pile are not widely ued&t i co!poite wood and concrete pile& %he ti!ber i

ept below groundwater and a greater o$er*all length i achie$ed& ' cloed*end pipe pile !ay be

ued in place of the ti!ber ection& Co!bination of two or !ore of a preceding type or

co!bination of different !aterial in the a!e type of pile& Co!poite pile are ued in ground

condition where con$entional pile are unuitable or unecono!ical concrete and ti!ber are the

type ued becaue it i cheap and eay to handle of the ti!ber pile with the durability concrete&

%he ti!ber i ter!inated below ground water le$el and the an upper portion for!ed in concrete&

e. Steel P"les

Steel pile( lie ti!ber( are dri$en by percuion !ean and ha$e a $ariety of uitable cro*

ection& n addition to the co!!on heet pile( the three !ain type are < ection( +o pile

and tube pile& %he !ain ue of teel pile i for te!porary wor( retaining wall and !arine

tructure& %he proble! of corroion of the teel can be o$erco!e by uitable protection& Sheet

pile ha$e the ad$antage of being robut( light to handle capable of carrying high co!prei$e


28/31

load when dri$en on to a hard tratu!( and capable of being dri$en hard to a deep penetration to

reach a bearing tratu! or to de$elope a high in frictional reitance( although their cot per

!etre run i high co!pared with precat concrete pile&

f. Con#rete P"les

Concrete pile !ay be di$ided into two bai categorie to precat pile and cat*in*itu pile&

Precat pile can be prepared by uing ordinary reinforce!ent( and they can be =uare or

octagonal in cro ection& Reinforce!ent i pro$ided to enable the pile to reit the bending

!o!ent de$eloped during picup and tranportation( the $ertical load( and the bending !o!ent

caued by a lateral load& %he pile are cat to deired length and cured before being tranported

to the wor ite&

So!e general fact about concrete pile are a follow /

i& Eual length / 3- ft to 9- ft

ii& Eual load / 9 ip to 79 ip

iii& 'd$antage /

a) Can be ubjected to hard dri$ing

b) Corroion reitant

c) Can be eaily co!bined with a concrete upertructure

i$& Diad$antage /

a) Difficult to achie$e proper cutoff

b) Difficult to tranport

Precat pile can alo be pretreed by the ue of high*trength teel pretreing cable& %he

ulti!ate trength of thee cable i about 2-i& During cating of the pile( the cable are

pretenioned to about 13- to 10- i( and concrete i poured around the!& 'fter curing( the

cable are cut( producing a co!prei$e force on the pile ection& Precat concrete pile ued on

!ediu! to large contract where oft oil o$erlaying a fir! trata are uncountered and at leat

1-- pile will be re=uired& %he precat concrete dri$en pile ha a little frictional bearing trength

ince the dri$ing operation !ould the cohei$e oil around the haft which reduce the poiti$e

frictional reitance& So!e general fact about precat pretreed pile are a follow /


29/31

i& Eual length / 3- ft to 19- ft

ii& "ai!u! length / 2-- ft

iii& "ai!u! load / 17-- ip to 10-- ip

%he ad$antage and diad$antage are the a!e a thoe of precat pile& Cat*in*itu(or cat*

in*place pile are built by !aing a hole in the ground and then filling it with concrete& ariou

type of cat*in*place concrete pile are currently ued in contruction( and !ot of the! ha$e

been patented by their !anufacturer& %hee pile !ay be di$ided into two broad categorie

caed and uncaed& +oth type !ay ha$e a pedetal at the botto!& Caed pile are !ade by

dri$ing a teel caing into the ground with the help of a !andrel placed inide the cating& Jhen

the pile reache the proper depth the !andrel i withdrawn and the cating i filled with concrete&

%he pedetal i an epanded concrete bulb that i for!ed by dropping a ha!!er on freh

concrete& So!e general fact about caed cat*in*place pile are a follow /

i& Eual length / 19 ft to 9- ft

ii& "ai!u! length / 1-- ft to 13- ft

iii& Eual load / .9 ip to 119 ip

i$& 'pproi!ate !ai!u! load / 1,- ip

$& 'd$antage /

a) Relati$ely cheap

b) 'llow for inpection before pouring concrete

c) Bay to etend

$i& Diad$antage /

a) Difficult to plice after concreting

b) %hin caing !ay be da!aged during dri$ing

Dr"/en Cast(In(Pla#e P"le

i& Dri$en cat*in*place pile intalled by dri$ing(to the deired penetration(a cloe ended teel

tube or concrete hell and the $oid created i filled with concrete& Steel tube or concrete hell

can be withdrawn or left in place&


30/31

ii& Readily adjutable in length to uit the deired depth of penetration&

iii& Bcono!ic if no caing re=uired&

Bore! Cast(In(Pla#e P"le

i& ' borehole i for!ed in the ground by ugar etc and the $oid concrete to for! bored pile&

ii& Eual i8e $arie fro! .--!! dia!eter to 1---!! dia!eter&

iii& 'llowable load $arie fro! ,--@ to 19--@&

i$& 6ength of bored pile eaily adjutable to uit the penetration depth&

$& Suitable in redidual oil

$i& Ee high lu!p elf co!pacting concrete&

$ii& %re! concreting if water in borehole&

%he uncaed pile are !ade by firt dri$ing the caing to the deired depth and then filling it

with freh concrete& %he caing i then gradually withdrawn& Following are o!e general fact

about uncaed cat*in*place concrete pile /

i& Eual length / 19 ft to 9- ft

ii& "ai!u! length / 1-- ft to 13- ft

iii& Eual load / 7 ip to 119 ip

i$& 'pproi!ate !ai!u! load / 1- ip

$& 'd$antage /

a) nitially econo!ical

b) Can be finihed at any ele$ation

$i& Diad$antage /

a) oid !ay be created if concrete i placed rapidly

b) Difficult to plice after concreting

c) n oft oil( the ide of the hole !ay ca$e in( =uee8ing the concrete

$. Steel ( Se#t"on P"les


31/31

Documents

Types of Foundation Made by Weisiong