pile foundation -types, failure, casting, driving

1. ADVANCED CONSTRUCTION
TECHNOLOGY
SUNDARRAJAN P
LECTURER / CIVIL

2. UNIT I
➢ 1.1 PILE FOUNDATIONS
➢ Definition, uses, types, classification, advantages and disadvantages
➢ load bearing piles and friction piles – purpose, sheet piles-types-description
➢ choice of type of pile - factors to be considered
➢ pile cap and pile shoe & load test on piles – description
➢ Pile driving – equipment’s, types of hammer , choice of hammer
➢ causes of failure of piles & Reinforcement requirements for R C piles.

3. What is Pile Foundation? (definition)
✓Kind of deep foundation formed by long or slender
column made of steel, concrete or timber used to
support the structure and transfer the load at desired
depth.
✓A foundation is described as 'piled' when its depth is
more than three times its breadth.

4. Uses
✓To resist uplift forces
✓To avoid settlement of foundation
✓Where groundwater table is high
✓Poor bearing capacity of soil
✓Heavy and ununiform loads
✓Canal or deep drainage exist near
✓Other foundations are uneconomical

5. Pile types
Load
bearing
Bearing
piles
Friction
piles
Non load
bearing
Steel sheet
piles
Concrete
sheet piles
Timber
sheet piles

6. Bearing&frictionpiles
Cast iron piles
Cement concrete
piles
Cast in situ
Precast
Sand piles
Timber piles
Steel piles
Wrought iron
piles
Composite piles

7. Load bearing pile
➢Transfers vertical loads from structure to hard soil or stratum through poor
soil.
➢To take horizontal load they are driven some inclination
➢Types :
1. Bearing or end bearing piles
2. Friction piles

8. • Bearing piles:
✓ Transfer load through water or soft
soil to hard stratum below certain
depth (act as column or pier)
• Friction piles:
✓ Transfer load through friction between
surrounding soil and pile surface when
loose soil extends to great depth

9. Timber piles
• Made of straight, sound and defect free timber
• Iron shoe is provided at bottom end for driving without damage
• Used to support light structure
• Transmission of load takes place by frictional resistance

10. Timber pile
Advantage
• Easy to handle
• Economical
• Undamaged in saturated soil
Disadvantage
• Cannot withstand hard driving
force
• Decay or deteriorate by insects/salt
water

11. Concrete pile
• A reinforced pile made of concrete, either precast and driven into the ground
, or cast in place in a hole bored into the ground.
• used to support offshore structures such as bridges, oil-rigs, and floating
airports
• Types
• Pre-cast
• Pre stressed
• Cast in situ

12. Concrete pile
Advantage
• Durable and corrosion resistant
• High capacity
• Relatively inexpensive
• Monolithically boned to pile cap
which is not possible in timber pile
Disadvantage
• Difficult to reduce or increase
length
• Transporting difficulties
• Handling difficulties
• Damaged by handling and
transportation

13. Steel pile
• Steel piles are made of steel pipes usually filled with concrete after being
driven.
• Wide beams and Steel ‘H’ sections are widely used as steel piles, specially if
conditions demand hard driving.
• Steel piles are usually of long lengths and have high working loads per pile

14. Steel pile
Advantage
• Easy to modify
• High capacity
• Small displacement of soil
• Good penetration through hard
materials
Disadvantage
• High cost
• High corrosion
• Noisy driving
• Difficult transportation

15. Composite pile
• Made of two different materials.
• Consist of upper portion of cast-in-situ concrete with lower portion timber
• Used rarely as it is difficult to provide proper joint between two or more
materials.
• Employed in special conditions

16. Composite pile
Advantage
• Very high load capacity
• Hard driving possible
• Corrosion resistant
Disadvantage
• High initial cost
• Difficult to install and handle

17. Sand pile
• One of the potential methods for improving ground stability,
preventing liquefaction, reducing settlement and similar applications.
• This method involves driving a hollow steel pipe into the ground.
• The bottom is closed with a collapsible plate down to the required depth and
then pipe is filled with sand.
• The bottom plate opens during withdrawal and the sand backfills the voids
created earlier during the driving of the pipe

19. Sand pile
Advantage
• cheaper when compared to other
similar ground improve techniques like
stone columns.
• Construction of the sand columns is
extremely fast
Disadvantage
• low stiffness when compared to other
methods. Hence larger percentage
replacement of weak soil is required.
• These piles do not have sufficiently
high permeability to function as
effective vertical drains during
earthquakes.

20. Stone piles
• Used as means of strengthening sub-strata by introducing a series of stone
columns using vibration or setting methods.

22. Encased piles
• constructed with timber poles or steel sections embedded and encased with
concrete.
• Temporary piles can be encased with sand or metal, and then the pole can be
removed once the pile has served its purpose.
• Concrete encasement provides additional strength and corrosion protection
to timber or steel piles.

23. Applications
• Retaining walls
• House foundations
• Corrosion protection
• Marine piles

24. R.C.C piles
• Designed for total load coming from structure
• Handling stress
• Driving stress
• Two types
• Pre cast
• Cast-in-situ

25. Pre-cast piles
• Casted and cured in yard and then transported to site for driving
• Made of uniform sections with pointed tips
• Designed to resist
• Bending stress during handling & transportation
• B.M from lateral loads
• Vertical loads

26. Pre-cast piles
• used for the most conventional foundation method.
• It's usually the quickest and also the cheapest method besides the use of
wooden piles.
• The main benefit of these concrete piles is the high vertical pile load
resistance.

28. Concrete mix & reinforcement (precast piles)
• Bottom (butt) and top (tip) region – 1:1:2 concrete
• Rest region – 1:1.5:3 concrete
• Longitudinal reinforcements – 4 to 8 nos. of 20 to 50mm dia. bar
• Lateral ties – 5to 10mm dia. bar
• Cover – 50mm
• Toe of pile- cast steel shoe

29. Sequence of Precast Concrete Pile
Production
• Casting
• Tensioning work in case of prestressed pile
• Curing
• Release in case of Pre tensioning pile
• Finishing
• Marking pile
• Handling and storage of pile

30. Casting of precast pile
1. From work is prepared and inside surface is coated solution or oil, to
prevent sticking of concrete.
2. Reinforcement cage is prepared as per design and put in the formwork.
Cover of 50mm is maintained around
3. Concrete is prepared as per required proposition and poured into the
formwork and well consolidated with vibrator
4. Formwork is removed after 3 days and kept in same position for 7 days and
shifted to curing tanks for 3 to 4 weeks after that they become ready for use

32. Pre-cast pile
Advantage
• Quality checked before driving
• Relatively inexpensive
• Don't corrode
• No spoil generated on site
• Unaffected by groundwater
• Stable in squeezing ground (weak)
Disadvantage
• Damaged during driving
• Relatively difficult to cut based on site
condition
• Cannot be drive large dia. ones
• Pile may get laterally displaced if it
encounters any obstructions like rocks
in the ground.

33. Cast-in situ piles
• Reinforced and cast at site only
• Cast in situ pile is a strong choice in the following conditions:
• If noise prevention to the buildings located around the construction.
• Bored cast in situ pile is ideal as end bearing pile, exclusively when it need to be
socketed into rock.
• When high capacity pile is required, then this type of pile is an ideal choice. preferred
for weights ranges from 150tonnes to 300tonnes.

34. Concrete mix & reinforcement
(cast-in situ piles)
• M20 or M25 concrete
• Longitudinal reinforcements – mini. 12mm dia. bar
• Lateral ties – 5to 10mm dia. bar
• Cover – 65mm

35. Construction procedure of cast in situ pile
• Set out pile points accurately based on the design drawings, Use total Station or
theodolite to set out pile position.
• Prepare a layout that illustrate the expected path for rig movement based on the
work program
• Position the rig over the established pile point. Diameter of the cutting tool shall
not less than the required pile diameter by more than 75mm
• Then drive the casing into the ground. Drive steel casing to a minimum a depth of
1 m below the ground level to take lateral loads and movements at site

36. Procedure continued
• stabilize the borehole during boring process using bentonite or other suitable
means.
• lower reinforcement cage with suitable cover into to the borehole vertically,
without disturbing the sides of the hole.
• Then poring of concrete is done.

38. Cast in situ pile
Advantage
• Low cost
• Installed at large dia. and long length
• No risk of ground heave
• Soil removed is tested
• Length can be modified as per site
requirements
Disadvantage
• Not useful for marine structure
• Difficult to maintain proper
compaction during construction
• Uncertainty in shape and condition

39. Non load bearing piles
• Used to resist lateral pressure from loose soil, seepage of water
• Not carry vertical load
• Ex. Sheet piles

40. Purpose of non load bearing pile
• Prevent transfer of machine vibration
• Construct retaining wall in marine works
• Prevent seepage of water or underground movement of water
• Protect foundation from erosion
• Confine soil and increase SBC of soil
• Protect river banks
• Prevents escape of soil and passage of shocks

41. Sheet piles
• Made of wood, concrete or steel
• Driven side by side to form continuous vertical wall for retaining soil
• Alignment and resistance are provided by horizontal braces or tie backs
• Used for retaining walls, land reclamation, underground structures, sea walls,
cofferdams and river bank protection
• Types
• Timber, steel and concrete

42. Selection of sheet piles depends on
• Type of work
• Site conditions
• Required depth
• Bending moment
• Nature of structure
• Protection type

43. Timber sheet pile
• Used for short spans in temporary structure
• Resist light lateral loads
• Connected together by tongue and groove joints
• 20cm to 30 cm wide
• 80 to 150mm thick
• 2 to 4m long
• Bottom edge fitted with iron shoe

44. Concrete sheet pile
• Formed using precast concrete members
• Connected together by tongue and groove joints
• Used in permanent river embankments, canals and other marine structures
• Toe of pile is cut for easy driving
• 50to 60cm wide
• 20 to 60 mm thick

45. Steel sheet pile
• Used for construction of coffer dams, permanent works in marine structure
• Made of thick steel sheets with interlocking arrangements so as to form
water tight joints
• 20 to 30 cm wide
• 4m to 5m long
• Strong and durable
• Drive by hammers

46. Choice of types of pile
• Location and type of structure
• Ground conditions
• Durability
• cost

47. Factors to be considered
• Nature of structure
• Type of loading
• Ground water level
• Length of pile
• Availability of materials and
equipment
• Depth of hard soil
• Physical properties
• Maintenance
• Cause of detrition of piles
• Cost

48. Pile cap
• Pile cap is like a slab below which there are various piles or a group of piles
are combine to act as a single pile which withstand the load from the
superstructure or column

49. Pile shoe

50. Pile load test

51. Types of pile load test
• Initial test
• performed before the start of construction to assess the design adequacy.
• the test load 2.5 times the working load
• Routine test
• performed on a working pile
• test load is 1.5 times the design load.

52. •

53. Pile load test load application
• Load applied in increment at the rate of 25 % of working load till working
load is reached
• For each load increment maintain the load constant till settlement is 0.1 mm
for 5 min as per IS Code, 0.1 mm for 20 min as per BS Code
• Go for next loading
• When working load is reached hold the load for 24 hr and unload
• Reload from working load to higher loads

54. Load application Contud…
• Hold load constant till settlement is 0.1 mm for 5 min as per IS Code, 0.1
mm for 20 min as per BS Code
• Repeat the process for subsequent load increments
• Go either up to 5/2 times the working load for initial or routine test or to a
settlement equal to 10 % of pile diameter for straight piles and 7.5 % of base
diameter for belled pile

56. Pile driving
• process of installing a pile into the ground without any excavation
• Should be driven vertically
• Eccentricity of 2% of pile length is permissible
• Driven into ground by a rig which supports the leads, rises the piles and
operates the hammer
• The weight is raised when it reaches highest point then it is released and
smashes into the ground

57. Pile driving equipment
• Pile frames
• Pile hammer
• Leads
• Winches
• miscellaneous

58. • Pile frame
• 10 to 25m height, Light and transported easily
• Platform on which engine, winches are fitted
• Pile hammer
• Delivers energy to pile to drive into the soil
• Leads
• Steel frame with 2 parallel members for guiding the piles in correct alignment
• Ram is a moving part of hammer consist of piston and driving head
• Winches
• Operated by steam, diesel, or electric motor to lift hammer and pile
• Miscellaneous
• Anvil, drive cap, etc.,

59. Types of hammer

60. Drop hammer
• Heavy metal weight lifted then released and allowed to fall on top of pile
• Because of this high dynamic force, pile cap is positioned between hammer
and pile head
• 220 to 1360Kgs
• 4-8 blow per minute
• Suitable for remote projects where
only few piles requires

61. Single acting steam hammer
• It has freely falling weight called a ram lifted by steam or compressed air
• When piston reaches the top of stroke steam or air is released and ram falls
freely to strike top of pile
• Falls on gravity
• Heavy weight strikes with low velocity
• fall distance 3 to 4 ft
• 40-60blows per minute

62. Double acting steam hammer
• Striking ram is driven by compressed air in both rising and falling
• 95 -300 blows per minute
• Low count smaller hammer vice versa
• Light and medium weigh piles into soils
having normal friction
• 90% energy delivered by action of air

63. Differential acting steam hammers
• Modified single acting steam hammer
• Air pressure used to lift the ram is not exhausted at the end of upward stroke
but used to accelerate ram on downward stroke
• Blows are comparable with double acting hammer
• Height and free fall comparable with single acting hammer
• 350-3600Kgs

64. Diesel hammer
• Self contained driving unit
• Simple and easily move from one place to other
• Open end hammer 40-55 blows per minute
• Closed end hammer 75-85 blows per minute
• Works well in cohesive or very dense layers
• Not operate in soft grounds

65. Vibratory hammer
• Effective in water saturated non cohesive soil
• Vibrations are transmitted to pile and
transmitted to adjacent soil
• It reduces skin friction between soil & pile
• Powered by hydraulic or electric

66. Choice of hammer
• Cost
• Available pressure
• Available head room
• Presence or absence of water
• Nature of work
• Materials used
• Position of piles (vertical, inclined)

67. Causes of failure of piles
• Lack of adequate boring
• Inaccurate soil classification
• Soft strata at tip of pile
• Improper size usage of hammer
• Mis interpolated load calculation
• Damage of encased pile
• Use poor quality concrete
• Overweigh due to earth fill
• Buckling of piles
• Breaking of piles
• Vibration cause later or vertical movement
• Tension failure due to lack of
reinforcement
• Eccentricity
• Decay
• Corrosion and marine bore insect attack

68. Reinforcement requirements of R.C piles
Concrete piles Longitudinal reinforcement Traverse reinforcement
Precast pile Mini. 1.5% of concrete area
At least 4 bars in symmetrical pattern
Mini. 6mm dia. bar
Cover <70 mm
Spacing <75 mm
Cast in situ or bored pile Mimi. 4 nos. of 13mm dia. bars Cover <65 mm
Under reamed bored pile Min. 0.4% of concrete area
3 10mm dia. bars provided to full
length
mini. 6mm dia.
Spacing less than 300 mm
Or stem dia. whichever is less
Under reamed compaction pile Mini. 4 12mm bar (length of pile
exceed 5m)
Mini. 6 12mm bar (dia. of pile exceed
375mm)
8mm stirrups