Lec 7 pile foundation

5-4-2014

2. PileFoundations

3. What is Pile Foundations?
PileFoundationmeansaconstructionforthe
foundationofaabutmentorpierwhichissupportedon
piles.
Pileisaslikeacolumnthatisdrivenintothe
foundationsoilorconstructedinsidethefoundation
soil.

4. Where Pile Foundations is Used?
oWhenstratumofrequiredbearingcapacityisatgreaterdepth
oWherethesoiliscompressible
oWherethesoilisWater-logged
oWheretheSoilisofmade-uptype
Examples;
oPilesareusedforfoundationforheavybridges,
oBuildings
oWaterfrontinstallations(piers,Wharf,docksetc).

5. Advantages of Pile Foundations
Providesacommonsolutiontoalldifficultfoundationsite
problems
Canbeusedforanytypeofstructure
Canbeusedinanytypeofsoil
Now-a-dayspilefoundationisvastlyinuseinsteadofwell
andcaissonfoundation.

6. Situations Which Demand Pile Foundation
Sub-soilwatertableissohighthatitcaneasilyaffect
theotherfoundations.
Loadcomingfromthestructureisheavyandnon
uniform.
Wheregrillageorraftfoundationsareeitherverycostly
ortheiradoptionimpossibleduetolocaldifficulties.
Whenitisnotpossibletomaintainfoundationtrenches
indryconditionbypumping,duetoveryheavyinflowof
seepageorcapillarywater.
Whenitisnotpossibletotimbertheexcavation
trenchesinthecaseofdeepstripfoundation.(strip
foundation-spreadfootingunderwall).

7. Situations Which Demand Pile Foundation
(Contd)
Whenoverlaysoiliscompressible,andwater-logged
andfirmhardbearingstrataislocatedatquitealarge
depth.
Whenstructuresarelocatedonriver-bedorsea-shore
andfoundationsarelikelytobescouredduetoaction
ofwater.
Largefluctuationsinsub-soilwaterlevel.
Canalordeepdrainagelinesexistnearthe
foundations.
Intheconstructionofdocks,piersandothermarine
structurestheyareusedasfenderpiles.

8. Types of Piles
a) Classification based on Function
or Use
b) Classification based on Materials
c) Classification based on method of
installation

9. Different PILES

10. Types of Piles Based on Function
a) Classification based on Function or Use
1.Bearing Piles or End Bearing Piles
2.Friction Piles or Skin Friction Piles
3.Tension Piles or Uplift Piles
4.Anchor Piles
5.Batter Piles
6.Fender Piles
7.Compaction Piles
8.Sheet Piles

11. Types of Piles Based on Function (contd)
Bearing Piles
Drivenintothegrounduntilahardstratumisreached.
Actsaspillarssupportingthesuper-structureand
transmittingtheloadtotheground.
Piles,bythemselvesdonotsupporttheload,ratheracts
asamediumtotransmittheloadfromthefoundationto
theresistingsub-stratum.

12. End Bearing Piles
ROCK
SOFT SOILPILES

13. Types of Piles Based on Function
(contd)
FrictionPiles
Pilesaredrivenatasitewheresoilisweakorsofttoa
considerabledepthanditisnoteconomicalorrather
possibletorestthebottomendofthepileonthehard
stratum,
Loadiscarriedbythefrictiondevelopedbetweenthesides
ofthepileandthesurroundingground(skinfriction).
Thepilesaredrivenuptosuchadepththatskinfriction
developedatthesidesofthepilesequalstheloadcoming
onthepiles.

14. Types of Piles Based on Function
(contd)
Friction Piles
Skinfrictionshouldbecarefullyevaluatedandsuitable
factorofsafetyapplied
Theloadcarryingcapacityoffrictionpilecanbeincreased
by-
increasingdiameterofthepile
increasingthedepthofpile
increasingthenumberofpiles(useasgroupof
piles)
makingsurfaceofthepilerough

15. SOFT SOIL
Friction Piles

16. Types of Piles Based on Function
(contd)

17. Types of Piles Based on Function
(contd)

18. Types of Piles Based on Function
(contd)
Anchor Piles
Pilesareusedtoprovideanchorageagainst
horizontalpullfromsheetpilingwallorotherpulling
forces.
Batterpiles:
Pilesaredrivenataninclinationtoresistlarge
horizontalandinclinedforces.

19. Types of Piles Based on Function
(contd)
Fenderpiles:
Pilesareusedtoprotectconcretedeckorotherwater
frontstructuresfromtheabrasionorimpactcaused
fromtheshipsorbarges.
Ordinarilymadeupoftimber.
Compactionpiles:
Whenpilesaredriveningranularsoilwiththeaimof
increasingthebearingcapacityofthesoil,thepiles
aretermedascompactionpiles.

20. Types of Piles Based on Function
(contd)

21. Types of Piles Based on Function
(contd)
Sheet Piles
Sheetpilesareneverusedtoprovideverticalsupportbut
mostlyusedtoactasretainingwalls.Theyareusedfor
thefollowingpurposes:
oToconstructretainingwallsindocks,andothermarine
works.
oToprotecterosionofriverbanks.
oToretainthesidesoffoundationtrenches.
oToconfinethesoiltoincreaseitsbearingcapacity.
oToprotectthefoundationofstructuresfromerosionby
riverorsea.
oToisolatefoundationsfromadjacentsoils.

22. Types of Piles Based on Function
(contd)
Figure: Sheet Piles

23. Types of Piles Based on Materials
b) Classification based on Materials
1.TimberPiles
2.ConcretePiles
3.Composite Piles
4.Steel Piles
5.Sand Piles

24. Timber
Concrete; Site cast or Precast
Composite
Steel; H-piles, Steel pipe
Types of Piles Based on Materials

25. Types of Piles Based on Materials
(contd)
1.TimberPiles:
Transmissionofloadtakesplacebythefrictionalresistance
ofgroundandthepilesurface.
Economicaltosupportlightstructure.
Pilesmade from timber of treelike
Sal,Teak,Deodar,Babul,Kailetc.
Maybecircular,squareinx-section.
Pilesaredrivenwiththehelpofpiledrivingmachineinwhich
drophammersdeliversblowsonthepilehead.
Broomingofpileheadispreventedbyprovidinganironring
oflessthan25mmindiameterthanthepileheadatthepile
top.

26. Types of Piles Based on Materials
(contd)
1.TimberPiles:
Tofacilitatedriving,thelowerendispointedand
providedwithacastironconicalshoe.
Pilesshouldnotbespacedlessthan60cmcenterto
center,thebestspacingis90cmc/c.closerspacing
destroysfrictionalresistance.
Maxloadshouldnotexceed20tonnes.
Pilesaresubjectedtodecayforalternatedryandwet
condition(onaccountofvariationofgroundwaterlevel)
Diametervariesfrom30to50cm.
Lengthshouldnotbemorethan20timestheleast
sectionaldimension.

27. Types of Piles Based on Materials
(contd)
AdvantagesofTimberPiles:
Economicalwheretimberiseasilyavailable.
Canbedrivenrapidly&assuchsavestime.
Becauseofelasticity,timberpilesarerecommendedfor
sitessubjectedtounusuallateralforcese.g.ship,ferry
terminals.
Donotneedheavymachineryandexpensivetechnical
supervision.
Beinglight,theycanbeeasilyhandled.
Theycanbeeasilywithdrawnifneeded.

28. Types of Piles Based on Materials
(contd)
DisadvantagesofTimberPiles:
Liabletodecayordeterioratebysaltwater/insects.
Restrictedlength.Itisratherdifficulttoprocurepilesin
requiredsizeandlength.
Lowbearingcapacity.
Theyarenotverydurableunlesssuitablytreated.
Itisdifficultorratherimpossibletodrivethesepilesinto
hardstratum

29. DRIVEN PILES(TIMBER, STEEL PIPE PILES)

30. 2.ConcretePiles

31. Concrete Piles (contd)
AdvantagesofConcretepiles:
Durabilityisindependentofgroundwaterlevel.
Forlargesizeandgreaterbearingpowernumberofpiles
requiredismuchless.
Canbecasttoanylength,sizeorshape.
Canbeusedtomarineworkwithoutanytreatment.
Materialrequiredformanufactureiseasilyobtainable.
Concretepilescanbemonolithicallybondedintopilecap
whichisnotpossibleinwoodenpiles.

32. Concrete Piles (contd)
DisadvantagesofConcretepiles:
Costlierthantimberpiles.
Cannotbedrivenrapidly.
Requiredcostlytechnicalsupervisionandheavydriving
machines.
Mustbereinforcedtowithstandhandlingstresses.

33. Concrete Piles
ConcretePilesareof2types:
a.Pre-castPiles
b.CastinsituPiles

34. Concrete Piles (contd)
a.Pre-castPiles:
Reinforced concrete piles, molded in
circular,square,rectangularoroctagonalform.
Castandcuredinthecastingyard,thentransportedtothe
siteofdriving.
Ifspaceavailableitcanbecastandcurednearthework
site.
Driveninsimilarmannerastimberpileswiththehelpof
pilesdrivers.
Diameternormallyvariesfrom35cmto65cm,lengthvaries
from4.5mto30m.

35. Concrete Piles (contd)
a.Pre-castPiles:
Functionofreinforcementinapre-castpileistoresistthe
stressesduringhandling,drivingandfinalloadingonthe
pileratherthanstrengthenthepiletoactasacolumn.
Longitudinalreinforcementsusually20mmto50mmin
diameter,stirrups6mmto10mmindia.
For90cmlengthatheadandtoe,stirrupsspacingis8cm
c/candforremainingintermediatelengthitisabout30cm
c/c.
Aconcretecoverof5cmismaintainedthroughout,overthe
mainsteelbars.

36. Concrete Piles (contd)
AdvantagesofPre-castPiles:
Veryeffective
Simplequalitycontrol
Improvestheentirearea
DisadvantagesofPre-castPiles:
Limitedinlength
Difficulttotransport
Notsuitablefordenselybuiltuparea
Requirescostlyequipment

37. R.C. SQUARE PILES
Size : 150mm to 400mm
Lengths : 3m, 6m, 9m and 12m
Structural Capacity : 25Ton to 185Ton
Material : Grade 40MPa Concrete
Joints: Welded
Installation Method : Drop Hammer

38. Precast Concrete Plies

39. RCC
Square
Piles

40. Pile Lifting

41. Pile Positioning

42. Concrete Piles (contd)

43. Concrete Piles (contd)
b.Cast-in-SituPiles:
Castinpositioninsidetheground.
Firstofallaboreisdug
Thenthesoilfromtheboreisdrawnout
Reinforcecageisplacedin
andfilledwithcementconcrete

44. Concrete Piles (contd)
AdvantagesofCast-in-SituConcretePiles:
Notlimitedinlength
Canbecastatanyplace
Requireslessequipment
Costislessandisdependedonthesize
DisadvantagesofCast-in-SituConcretePiles:
Qualitycontrolisdifficult

45. Concrete Piles (contd)
Figure: Cast-in-Situ
Pile

46. Site Cast Concrete Piles
Cased Piles Uncased Piles

47. 47
FOOTING
Pile Cap for Column Footing (Cast-in-situ Pile)

48. 48
COLUMN FOOTING (on Cast-in-situ Pile)

49. F
z
F
y
F
x
-M
y
M
x
Beam seat elevation
Rock
Loose Sand
Applied Loads

50. Composite Piles
Pilesoftwodifferentmaterialsaredrivenoneoverthe
other,soastoenablethemtoacttogethertoperformthe
functionofasinglepile.
Thistypeofcompositepileisusedwiththeobjectof
achievingeconomyinthecostofpilingwork.

51. CompositePiles

52. STEEL PILES
Steelpilesareofsteelsection.Usefulwheredriving
conditionsaredifficultandothertypesofpilesarenot
suitable.Usuallyusedforbuildingandbridgefoundations.
ThepilesareinformofI,Hsectionsandsteelpipepiles.
Steelpilesareavailableinthefollowingforms.
SteelHpiles
Sheetpiles
Discpiles
Screwpiles.

53. STEEL –H PILES
Similar to I-beam except that cross-section is
generally heavier and the flange width and distance
from flange face to flange face is nearly the same.

54. STEEL –H PILES, DRIVEN PILES
ThefollowingphotosequencewastakenatthesiteoftheNashville
Coliseum
67,000seatsportsStadiuminNashville,TN
–DeepFoundationsisadopted:
3,500DrivenPiles;12x53HPiles(EndBearing)
Pilelengthvariedfrom25’-75’
Used3PileDrivers(DieselPoweredHammers)
Drivingrate:20-25piles/day/rig

55. DRIVEN H-PILES

58. C)Classification based on method of installation
Large displacement piles
They consist of all solid driven piles (e.g
precast concrete piles, steel or concrete tubes
closed at the lower end, Timber piles)
Small displacement piles
They include rolled steel sections such as H-
pile and open-end tubular piles
Replacement piles
They are formed by machine boring, grabbing
Types of Piles as method of installation

59. Combinations of vertical, horizontal and
moment loading may be applied at the soil
surface from the overlying structure
For the majority of foundations the loads
applied to the piles are primarily vertical
For piles in jetties, foundations for bridge
piers, tall chimneys, and offshore piled
foundations the lateral resistance is an
important consideration
Pile installation will always cause change of
adjacent soil properties, sometimes
good, sometimes bad.
H
V
M
Loads Applied To Piles

60. Selection of Type of Pile
Thenatureoftheground,wherepilingoperationistobe
carriedout,determinestoalargeextentthechoiceoftype
ofpiletobeused.
Inaddition,theotherimportantfactorswhichmustbe
consideredinthisregardare:
oThenatureofthestructure.
oLoadingconditions.
oElevationofthegroundwaterlevelwithrespecttothepile
cap.
oProbablelengthofpilerequired.
oAvailabilityofmaterialsandequipment.
oFactorswhichmaycausedeteriorationofpile.
oProbablecostofpile.

61. Causes of Failure of Piles
Loadonthepileismorethanthedesignedload.
Defectiveworkmanshipduringcastingofthepile.
Displacementofreinforcementduringcasting.
Bearingpilerestingonasoftstrata.
Improperclassificationofsoil.
Improperchoiceofthetypeofpile.
Insufficientreinforcementinthepile.
Decayoftimberpilesduetoattackbyinsects.
Bucklingofpilesduetoinadequatelateralsupport.
Defectivemethodadoptedfordrivingthepile.
Incorrectassessmentofthebearingcapacityofthepile.
Lateralforcesnotconsideredinthedesignofpiles.

62. Pile Driving Methods

63. Pile Driving Methods
I.Hammering.
II.Water Jets (Wash Boring ).
III.Boring (Auger Boring).

64. Drop Hammer.
Steam Hammer: single-acting, double-acting
Air Hammer: single-acting, double-acting,
Diesel hammer: single-acting (open end) or
double-acting (closed end)
Hydraulic Hammer
Vibratory Hammer
Types of Pile Driving Hammers

65. Thedrophammeristhesimplestandoldesttypeof
impacthammer.Ahammerwithapproximatelythe
weightofthepileisraisedasuitableheightina
guideandreleasedtostrikethepilehead.Thisisa
simpleformofhammer.
Drop Hammer

66. Drop Hammer
Hammer is raised by a rope or a steel cable
Then it is allowed to drop on pile cap
The weight of drop varies from 230-1800 kg
Weight depends on the shape and length of
pile and the nature of the ground
Takes a lot of time

67. Drop Hammer Method

71. Steam Hammer
Hammer is automatically raised and
dropped.
A steam cylinder and piston is used.
Steam pressure and the rate of hammer
blow are kept uniform.
Steam Hammers are of two types
Single Acting Type
Double Acting Type

73. Steam Hammer
Pile Driving
Equipment
mobile crane (usually
crawler)
leads: fixed or swinging
hammer, helmet, &
cushion
compressor (if air driven)
hydraulic unit (if vibratory)
steam plant (becoming
obsolete)

74. FOUNDATIONS
Steam Hammer

75. AirHammer: single-acting

77. DIESEL DROP
HAMMER
DRIVING

78. HYDRAULIC
HAMMER DRIVING

79. Pile Driving Hammer

80. Wash Boring
Wash boring is a fast and simple method for advancing holes in
soft to stiff cohesive soils and fine sand. This method is nt
suitable for boulders soil and rock.
The method consists of first driving a hollow steel pipe known
as casing pipe/drive pipe in to the ground.
Through this casing pipe, a hollow drilled rod with a sharp
chisel or chopping bit at the lower end known as water jet pipe
or wash pipe is inserted.
Upper end of wash pipe is connected to water pump and lower
end is contracted to produce jet action.

81. Wash Boring (contd)
Water is forced under pressure through the drill rod which is
alternatively raised and dropped, and also rotated. The
resulting chopping and jetting action of the bit and water
disintegrates the soil.
The cuttings are forced up to the ground surface in the form of
soil-water slurry through the annular space between the drill rod
and the casing.
The slurry is collected and samples of materials are obtained by
settlement.

83. Wash Boring (contd)
Interpretation of Results
The change in soil stratification is guessed from the rate of
progress of driving the casing pipe and from the color of slurry
flowing out.
Results give fairly good information about the nature of the sub-
soil strata.
Disadvantages
Finer particles such as clay, loam etc do not settle easily.
Larger and heavy particles may not be brought up at all.
Exact location of materials (in bore length) can not be easily
determined.

84. BORED PILES

85. BORED PILES
Cast-InIn-SituPilesmaybeofLargeDiameter
Size:450mmto2m(Upto3.0mforspecialcase)
Lengths:Varies
StructuralCapacity:80Tonto2,300Tons
ConcreteGrade:20MPato35MPa(Tremie)
Joints:None
InstallationMethod:DrillthenCast-In-Situ

86. Boring Methods for Cast-in-situ
concrete Piles
Boring method is adopted for in-situ piles in hard soil
or soft rock.
Various boring methods are given following;
Percussion method
Augur Boring method
Rotary Drilling

87. AUGAR BORING
Stepsinaugar/rotarydrilling;
Boringiscontinueddowntoplanneddepth(usingaguiding
tube/rod)
Usingbentonitemud(slurry)underthegroundwaterlevel
Placingofreinforcement
Placingoftheconcreteandremovingofftheguidingtube

89. Loose
Silty sand
Hard Clay
Driven
HP 12 x 53
4'
35'
>100’
f= 31
o
sat= 110 pcf
sat= 125 pcf

90. Piles Subject to Scour
10.5.5.3.2
90

93. Geotechnical Profile of
the Site

94. THANK YOU