Pile foundations

Pile foundation is important for construction of foundation where bearing capacity of soil is poor. Pile foundation is use for distribution of uneven load of superstructure.There are so many type of pile are use for construction. Here i present some of pile with suitable condition for construction and methods for construction.
Thank you.

1. Pile foundation Prepared by: Thaiyam Sameer K. Assistant Professor Darshan Institute of Engineering & Technology Rajkot.

2. Pile foundation Introduction Use of piles Selection of type of pile Types of piles Pile cap and pile shoes Pile driving equipment and method Micro piling Pulling of piles Causes of failure of pile

3. Types of foundation Shallow foundation Deep foundation Pile foundation Cofferdam foundation Caissons foundation

4. What is pile ? A pile is a slender structural member made of concrete, steel, wood or composite material. A pile is either driven into the soil or formed in-site by excavating a hole and filling it with concrete.

5. Pile foundation Pile foundation is that type of deep foundation in which the loads are taken to a low level by means of vertical members which may be Timber Concrete steel

6. Uses of Piles The load of the super-structure is heavy and its distribution is uneven. The top soil has poor bearing capacity . The subsoil water is high so that pumping of water from the open trenches for the shallow foundation is difficult and uneconomical. Large fluctuation in subsoil water level . The structure is situated on sea shore or river bed, where there is danger of scouring action of water . Canal or deep drainage line exist near the foundation. For foundation of transmission towers and off-shore platforms which are subjected to uplift forces.

7. Scouring Off shore platform Transmission Tower

8. Factor Affecting Selection Of Type Of Piles Nature and type of structure Location Material, equipment and fund availability Type of soil and its properties Ground water table Durability of pile Length and number of pile Case study of adjacent building Facility for pile driving Erosion of soil near structure

9. Classification of Piles Based on function Based on materials Based on method of installation

10. Based on function End bearing Pile Friction Pile Compaction Pile Tension Pile Anchor Pile Fender Pile Better Pile sheet Pile

11. End bearing Pile Penetrate through the soft soil Bottom or tips rest on hard strata Work as column For this pile Qu= Qp where, Qu=ultimate load Qp = Pile load

12. Friction Pile Loose soil extend to a greater depth Pile are driven at depth when friction resistance developed equal to load In that case Qu=Qs ( Qs= skin friction ) Total friction resistance can be increased Increasing length and diameter Making Pile surface rough Placing closely or grouping of pile

13. Compaction Pile Pile do not carry any load For increase the bearing capacity of soil

14. Tension pile When structure subjected to uplift due to hydrostatic pressure or over turning moment Also known as uplift pile

15. Anchor piles These provided anchorage against the horizontal pull from sheet pulling or any other pulling .

16. Fender pile These are used to protect water front structures against impact from ships or other floating objects.

17. Better Pile They are used for resist large horizontal forces or inclined forces.

18. Sheet Pile They are used as bulk heads or as impervious cutoff to reduce seepage and uplift under hydraulic structures. Sheet pile is classified as, Concrete sheet pile s Steel sheet pile Timber sheet pile

19. Classification Based on Pile Material Concrete pile Steel piles Timber piles Composite pile Sand pile

20. Concrete Piles Pre cast piles Cast-in-situ Pre stressed

21. Pre Cast Concrete Pile It is those which are manufactured in factory or at a place away from the construction site and then driven into ground at the place required. It requires heavy pile driving machinery . It may be square, octagonal or circular in cross section. Size of pile vary from 30 cm to 50 cm in cross section and up to 20 m or more length . Grade of concrete should be M20 .

22. Cast In Situ A bore is dug into the ground by inserting a casing. Bore is filled with cement concrete after placing reinforcement The casing be kept in position or it may be withdraw. The piles with casing are known as cased cast in situ concrete pile. The piles without casing are known as uncased cast in situ concrete pile.

23. Cased Raymond piles Mac Arthur piles BSP base driven piles Swage piles Button bottom piles

24. Raymond Pile It used primarily as a friction pile . It is provided with uniform taper of 1 in 30 shorter pile. The length of piles vary from 6 to 12 m . Top diameter = 40 to 60 cm. Bottom diameter = 20 to 30 cm Collapsible mandrel is driven into ground. When the pile is driven to the desired depth mandrel is collapsed and withdraw . The shell is gradually filled with concrete up to the top.

25. Mac A rthur pile Mac Arthur is pile of uniform diameter using the corrugated steel shell which remain in place as in Raymond piles. A heavy steel casing with a core is driven into the ground. When the desired depth is reached, the core is withdrawn and a corrugated steel shell is placed in the casing. Concrete is placed in the shell by gradually compacting and withdrawing the steel casing.

26. BSP base driven piles This pile consist of a helically welded shell of steel plate. A concrete plug is provided at the bottom of the shell. Driving is done by allowing hammer to fall on the concrete plug . The casing is driven to the desired depth and then it is filled with concrete.

27. Swage piles It is used with advantage of driving in very hard or it is designed to leave water tight shell for some time filling of the concrete. steel shell is placed on a precast concrete plug Pipe is driven over plug until the core reached the plug, then pipe is swage out by tapper of plug which form water tight joint. Pipe is driven up to specified depth by help of driven force of core. Core is removed and pipe is filled with concrete.

28. Button B ottom piles It is used where increase of end bearing area is required. Pile use concrete plug shape of button which enlarge hole in soil during driving. It used for length up to 23 m and load up to 50 tones . 12 mm thick steel pipe set on concrete button which have diameter of 25 mm. Pipe and button driven to specified depth. The casing is removed and concrete is placed with reinforcement.

29. Uncased Simplex Franki Vibro Pedestal P ressure

30. Simplex Piles Simplex piles can be driven through soft or hard soil . Steel tube fitted with a cast iron shoe is driven into ground up to desired depth. If Reinforcement is necessary it put in tube then concrete is poured in pile. Tube is withdrawn slowly without concrete being tamped.

31. Franki Piles It is used at placed where high load is transfer.(ex . marine structure ) Plug of dry concrete is formed on ground by heavy removable pipe shell. By help of Diesel operated hammer of 20 to 30 KN weight plug is driven at desired depth. Diameter of pile is 50 to 60 cm ,while at enlargement is about 90 cm . Capacity of pile is 60 tones to 90 tones .

32. Vibro Piles This type of pile is best suited for places where the ground is soft and offers little frictional resistance to the flow of concrete. Pile are formed by driving a steel tube and shoe, filling with concrete and withdraw steel tube. Diameter of pile 35 to 50 cm for load of 60 to 70 tones . Length of pile is 25 m and above. Steel tube fitted with cast iron shoe by 2-2.5 tone hammer by 40 blow per minute , with stroke about 1.4 m When shoe and tube reached the desired level tube is filled with concrete and tube is withdrawn at 80 blow per minute by hammer . Steel tube is withdrawn leaving the shoe in place and pile is formed with corrugation along its height.

33. Pedestal Pile It is used where thin bearing stratum is reached with reasonable depth . Pedestal pile gives the effect of spread footing on thin bearing stratum. Core and casing are driven together into the ground till reached the desired level. Core is taken out and a charge of concrete is placed in the tube. The core is again placed in the casing to rest on the top of poured concrete. Pressure is applied on the concrete though the core, and as th e same time the casing is withdrawn .

34. Pressure Pile These piles are especially suitable for congested site where heavy vibration and noise are not permissible . Boring is done up to required depth to tube. After withdrawn boring tool reinforcement is placed if required. A layer of concrete is laid and pressure cap is provided at the top of tube . Compressed air is admitted through pipe which cause rise the tube. Tube is lifted same time of concreting is doing by means of compressed air . Care should be taken that some portion of concrete remain at bottom when tube is lifting for receiving new layer.

35. Steel Piles Commonly used steel piles are; H-piles Box piles Tube piles

36. H-piles These pile are usually of wide flange section. They are suitable for trestle type structure in which pile extend above ground level and act as column . They have small cross section area, there for they can be easily driven In soil. It used as long pile with high bearing capacity.

37. Box Piles They are rectangular or octagonal in form filled with concrete. These pile are used when not possible to drive H-piles into hard strata .

38. Tube Piles Tubes or piles of steel are driven into the ground. Concrete is filled inside the tube piles. Because of circular cross section tube piles are easy to handle and easy to drive in.

39. Timber Piles These pile are prepared from trunks of trees. They may be circular or square . Diameter of pile are 30 to 50 cm and length not exceeding 20 times its top width. At bottom, a cast-iron shoe is provided and at the top a steel plate is fixed. For group pile each pile is brought at same level and concrete plate is provided to have common platform .

40. Composite Piles This is a type of construction in which piles of two different material are driven one over the other. They act together to perform the function of a single pile. In this pile advantage is taken of durability of concrete piles and the cheapest of timber pile . Timber pile is terminated just at the level of ground water table .

41. S and Piles These pile are formed by making hole in ground and fill with the sand and well rammed . The sand to be used should be moist at time of placing . Bore hole diameter usually 30 cm. length of sand pile is kept about 12 times its diameter. The top of sand pile is filled with concrete. Sand pile are placed at 2 to 3 m spacing. Load test should be carried out determining the bearing capacity of sand pile. Properly compacted sand pile can carry load up to 100 tone/m 2 or more.

42. Classification Based on Method of Installation Driven pile Driven and cast-in-situ pile Bore and cast-in-situ piles Screw piles Jacked pile

43. Driven pile These pile are driven into ground by applying blow with a heavy hammer. Timber, steel and precast concrete pile are installed b y driving.

44. Driven and cast-in-situ pile These pile are formed by driving a casing with a closed bottom end into the soil . The casing is later filled with concrete. The casing may or may not be withdrawn.

45. Bore And Cast-in-Situ Piles These pile are formed by excavating a hole into the ground and then filling it with concrete.

46. Screw Piles

47. Jacked pile These piles are jacked into the ground by applying a downward force by a hydraulic jack .

48. Under Reamed Piles These piles are developed by C.B.R.I for serving foundation for black cotton soils , filled up ground and other type of soil having poor bearing capacity .

49. Under reamed piles An under reamed pile is bored cast-in-situ concrete pile having one or more bulbs or under reamed in its lower level. The bulb or under reamed are formed by under reaming tool . Diameter of pile is 20 to 50 cm and bulb diameter is 2-3 times of diameter of pile . Length of pile is 3 to 8 m and spacing between piles are 2 to 4 m. Load carrying capacity can increase by making more bulb at the base . The vertical spacing between two bulb is varies from 1.25 to 1.5 times diameter of bulb. For black cotton soil the bulb is increase bearing capacity and also provide anchorage against uplift.

50. Construction of Under Reamed Piles The equipment required for the construction of pile are, Spiral auger - for boring Under reamer - for making bulb Boring guide -to keep the hole vertical

51. Boring Using Spiral Auger Making Bulb Using Under Reamer

52. Placing of Concrete Placing of Reinforcement

53. Pile Accessories Pile cap Pile shoe

54. Pile Cap To protect the top of pile from blow of hammer on top, pile cap is provided. Pile carry load from structure and distribute it to various pile . Generally, Pile cap is made of steel. Thickness and size of cap is depend on shape and size of pile hammer . Pile should penetrate into the cap at least 10 cm length . For group pile a common R.C.C. is provided for all the pile.

55. Pile shoe There for pile shoe is fitted at bottom end of pile to protect the pile and to facilitate easy pile driving. Pile shoe are made of cast iron, steel or wrought iron . Various types of shoe are; Square pile shoe Wedged shaped pile shoe Round pile shoe Steel trap pile shoe for timber pile Socket type pile shoe for timber pile closed end shoe for pipe piles

56. Pile driving Equipment The operation of inserting pile into ground is known as pile driving. Pile are driven into the ground by means of hammer. The equipment used for lifting hammer and allow to fall on head of pile is known as Pile driver. Various method for pile driving are; Hammer driving Vibratory pile driver Watter jetting and hammering Partial angering method

57. Factor for selection of pile driving method Type of soil at site Costs of pile driving equipment Availability of fluid pressure Material of pile Length of pile Ground water level etc ……

58. Hammer driving Equipment required for hammer driving Pile frame or pile driving rig Pile hammer Leads Winches Miscellaneous equipment

59. Pile Frame Or Pile Driving Rig Pile drive with crawler mounted crane rig commonly used for pile driving. The hammer is guided between two parallel steel channel known as leads .

60. Leads Leads are also called leaders . It is used to guide hammer and pile for alignment. In case of drop hammer fixed lead are used. Lead can be movable and can be adjusted as per the requirement. Movable leads are more convenient as they can adjusted as required.

61. Winches Winches are used for lift hammer and pile . It should be light with single drum provision or heavy with double drums . Winches may be fitted with reverse gear system. Winches are driven with diesel or petrol engines or electrical power in case of drop hammer and pneumatic hammers.

62. Pile hammer Types of hammer used for driving the pile are; Drop hammer Single acting hammer Double acting hammer Diesel hammer Vibratory hammer

63. 1. Drop hammer The drop hammer is the oldest type of hammer used pile driving. A drop hammer is rise by a winch and allowed to drop the top of the pile under gravity from a certain height. During the driving operation a cap is fixed to the pile and cushion is generally provided between the pile and the cap . Another cushion known as hammer cushion is placed on the pile cap on which the hammer causes the impact.

64. 2.Single acting hammer In this hammer the ram is raised by air or steam under pressure to the required height. It is then allowed to fall under gravity on the top of the pile cap. The weight of hammer is about 1000 kg to 10,000 kg.

65. 3. Double acting hammer In double acting hammer raise by using air or steam pressure and drop the hammer. When hammer has been raised to the required height steam or air pressure is applied to other side of piston and the hammer is pushed downward under pressure . The weight of the hammer may be about 1000 kg to 2500 kg . It can be apply 90 to 240 blow per minute . It is used for driving light to moderate weight piles in soils of average resistance against driving.

66. Vibratory hammer

67. Pulling Of Pile To replace the damaged piles during the driving operation. To reuse the existing piles when the structure above the pile is demolished. To prepare the data of strata trough which piles are to be driven by carrying out pulling tests . To remove the pile which are driven temporarily as in case of a cofferdam.

68. Method For Pulling Of Pile The method for pulling of piles will depend on the type of pile, equipment availability. Various method are; Use of double acting steam hammer Use of pile extractors Use of tongs Use of vibrator Use of electricity

69. Pile Extractor

70. Vibration Pulling

71. Failure of Pile

72. Causes Of Failure Of Pile Most common causes of failure of piles; Absence of statistical data of nature of soil strata Load coming on pile is high than design load. Bad workmanship Attack by insets on wood Breakage due to over driving (timber pile) Buckling of pile Damage due to absence of protective cover Improper type of pile, method of driving, classification of soil Insufficient reinforcement in case of R.C.C Misinterpretation of result from pile load test. Wrong formula use for determining load bearing capacity.

73. Causes of Failure of R.C.C. piles Improperly designed concrete mix. Use of wrong type of cement Insufficient concrete cover to the reinforcement Early removal of concrete form. Use of aggregate that react with the type of cement.

74. Micro pilling A Micro pile is a small diameter , typically less than 300mm . A drilled and grouted non-displacement pile which is heavily reinforced and carries most of its loading on the high capacity steel reinforcement . Reinforcement and cement grout are the major component of micro pile. It also known as mini pile .

75. Construction of micro pile Following step are carried out for construction of micro pile. Drilling and/or installation of temporary casing Remove inner drilling bit rod. Placing reinforcement and grouting by tremie. Remove temporary casing, inject further grout under pressure. Complete pile (casing may be left in place of compressible stratum)

76. Application of micro pile For structure support New foundation Under pinning of existing foundation Seismic retrofitting of existing structure Scour protection Excavation support in confined area For situ reinforcement Slop stabilization Earth retention Ground strengthening and protection Settlement reduction

77. Advantages of micro pile It used to underpin the existing structure where need of minimum vibration It can be easily laid where low head room is constraint. It can be installed at any angle. It offers practical and cost effective solution to costly alternative pile system. Not require large access road or drilling platforms

78. Pile driving formula Load carrying capacity of pile can be determine following method; Dynamic formula Static formula

79. Dynamic formula Dynamic pile formula are useful in estimating pile capacity . The dynamic formula are based on assumption that the kinetic energy delivered by hammer during driving operation is equal to the work done in penetrating the pile . Kinematic energy delivered=work done in penetration Wh h = R x s + energy loss   W=weight of hammer (KN) h= height of fall of hammer h = Efficiency of hammer R= pile resistance taken equal to Qu S=penetration of pile per blow

80. Various Dynamic formula Engineering News Record (ENR) formula Hiley’s formula Danish formula

81. Engineering News Record formula As per the Engineering News formula the allowable load of driven pile is given by Q a =   Q a = Allowable load in kg W = Weight of hammer h = Height of fall in mm s = Final settlement per blow known as set c = Empirical constant ( drop hammer= 25 mm, single acting hammer=2.5 mm) F = Factor of safety (Usually taken as 6)

82. Hiley’s formula Hiley’s gave the formula which take into various energy loss. Qu = Qu=ultimate load on pile W=weight of hammer h = Height of fall of hammer C=elastic compression h =efficiency of hammer ( drop hammer =100%, single acting hammer = 75-85 %, double acting =85%) S= Avg. settlement per blow  

83. Danish formula Qu = =Elastic compression of pile = { } 1/2 L = Length of pile A= Area of cross section of pile E=Modulus of elasticity of pile material Allowable  

84. Static Formula In static formula ultimate bearing capacity of pile is considered to the sum of end bearing pile and resistance of skin friction. Qu= Qp +Qs = q p .A p + f s .A s Where, Qp =end bearing resistance qp = unit end bearing resistance Ap =area at the base Qs= skin friction resistance fs= unit skin friction As= surface area