Driven & Bored Piles

1. Driven and Bored Piles Made by : ahmed Mohamed Zanaty 9103710 ahmed Abdullah negm 9104441 Mohamed ahmed el saeid 9103644 abdelrahman Mohamed 9104286 ahmed Youssef 9100499 Departure : Course: construction & building Foundation Under supervision of: Prof. adel belal 1 To view online:

2. What is Deep foundation ? A deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground. There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation, but some of the common reasons are very large design loads, a poor soil at shallow depth, or site constraints There are different terms used to describe different types of deep foundations including the pile, the pier, drilled shafts, and caissons . 2

3. What are Piles ? Piles are generally driven into the ground in situ; other deep foundations are typically put in place using excavation and drilling. The naming conventions may vary between engineering disciplines and firms. Deep foundations can be made out of timber, steel, reinforced concrete and pre-stressed concrete. 3

4. How piles are connected ? Foundations relying on driven piles often have groups of piles connected by a pile cap (a large concrete block into which the heads of the piles are embedded) to distribute loads which are larger than one pile can bear . Pile caps and isolated piles are typically connected with grade beams to tie the foundation elements together ; lighter structural elements bear on the grade beams, while heavier elements bear directly on the pile cap. 4

5. Pile installation Pile installation is as important as design. There are two methods of installation : a)Installation by Driving b)Installation by Boring 5

6. Pile installation Before going through pile installation methods understand the following terminology . Driven pre-cast pile: The pile is casted in a yard brought to the site and driven by some mechanism into the soil. Driven Cast-in-situ pile: A casing plugged at bottom is driven into the ground and then the pile is casted by removing or retaining the casing. Bored Pre-cast pile: A bore is made and the soil inside is removed and then a pile casted in some yard is put into the bore. Bored Cast -in-situ pile: A bore is made the soil is removed and the pile is casted at site in the bore. 6

7. Choosing Pile Type 7

8. 8 Advantage & Disadvantage of Driven Piles

9. Driven Pile installation 9

10. Driven Pile installation All pile driving equipment, including the pile driving hammer , hammer cushion, helmet, pile cushion, and other appurtenances to be furnished by the Contractor shall be approved in advance by the Engineer before any driving can take place . To obtain this approval, the Contractor shall submit a description of pile driving equipment to the Engineer before pile driving begin . The description must contain sufficient detail so that the proposed driving system can be evaluated by the Engineer. 10

11. Hammer Types Drop hammer / Gravity hammer Single acting power driven hammer Double Acting Power Driven Hammer Diesel Power Driven Hammers Vibratory and Sonic Power Driven Hammers 11

12. Drop hammer / Gravity hammer: This is the original pile driving hammer. It consists of a steel ram that is guided within a set of leads. The hammer is raised to a certain height and allowed to drop on top of the pile, thus producing the driving reaction. Hammer Types 12

13. Hammer Types Single acting power driven hammer: Hammers of this type are basically power gravity hammers . The difference between a gravity hammer and a single acting power hammer is that the ram (striking part) is encased in a steel frame work and is raised by steam or compressed air rather than by the crane load lines. The frequency of the blows is also considerably higher than a drop hammer . The ram mass is usually greater than a drop hammer and the vertical travel is usually less than that of a drop hammer. Any type of power hammer is usually more efficient than a drop hammer because there is less time between blows for the soil to set up around the pile. 13

14. Hammer Types Double Acting Power Driven Hammer: The ram is raised by steam or compressed air, as in the case of the single acting power hammer. When the ram approaches the top of its stroke a valve is opened into a chamber at the top of the cylinder allowing high pressure air or steam into the cylinder forcing the ram downward. Some double acting hammers utilize a light ram, operating at a high frequency, to develop the energy blows comparable to those developed by heavier, slower acting hammers. The advantage of the lighter ram hammer is that there is less time between blows for soil to re-settle against the pile, thus increasing the driving efficiency and decreasing the drive time. 14

15. Hammer Types 15 Diesel Power Driven Hammers: They are simply a one cylinder diesel engine consisting of a steel cylinder containing a ram and an anvil. The ram is raised initially by an outside power source (crane) and dropped. As the ram drops, it activates a fuel pump, which injects fuel into a cup in the top of the anvil. The ram continues down blocking the exhaust ports and compressing the air in the combustion chamber. A ball on the end of the ram, mating closely with the cup in the anvil, forces the fuel into the hot compressed air between the ram and the anvil. The fuel then explodes forcing the ram up and forcing the anvil, and in turn, the pile down.

16. Hammer Types Vibratory and Sonic Power Driven Hammers: These are the most recent developments in pile hammer technology. They are comparatively heavy, requiring handling equipment of greater capacity than required for conventional pile hammers. The Vibratory Hammer vibrates the pile at frequencies and amplitudes which tend to break the bond between the pile surface and the adjacent soils, thus delivering more of the developed energy to the tip of the pile. 16

17. Driven Pile installation Raising the piston (starting ) Injection of diesel fuel and compression Impact and atomization. Exhaust Scavenging 17

18. Driven Pile installation 1.Raising the piston (starting ): For starting the diesel hammer, the piston (ram) is raised by means of a mechanical tripping device and is automatically released at a given height . 2 . Injection of diesel fuel and compression: As the piston falls through the cylinders, it activates a lever on the back of the fuel pump, which injects a measured amount of diesel fuel on to the top of the impact block. Shortly after this, the exhaust ports are closed. 18

19. Driven Pile installation 3. Impact and atomization: Compressing all the air /fuel between the exhaust ports and the top Of the impact block, the piston continues falling until it strikes the top of the impact block. The heat generated by the compression of air, in the presence of atomized fuel, causes the explosion of the fuel, throwing the piston upward and forcing the impact block downward against the pile. 19

20. Driven Pile installation 4. Exhaust: While moving upwards, the piston will pass and open the exhaust ports. Exhaust gases will escape and the pressure in the cylinder will equalize . 5 . Scavenging: The piston continues its upward momentum, which draws in fresh air for the nextcycle , cools the cylinders, and releases the pump lever. The pump lever returns to its startingposition , so that the pump will again be charged with fuel. Gravity stops the upward motion of thepiston and it starts falling through the cylinders once again. 20

21. Driven Pile installation 21

22. Driven Pile installation 22

23. Design of driven pile in sandy soil 23 Using static formula: Length of pile = 25 m , D iameter of pile = 50 cm , γ = 18 , Ø = 30 ° Qult = q Nq л + Σ KHc Po tan δ. 2 л R ΔH q = Ø = 30 + 40/2 = 35 , Nq = 75 Qb = π P = QS = Σ KHc Po tan δ. 2 л R QS = Q1 + Q2  

24. Design of driven pile in sandy soil 24 (Cont.) Design of driven pile in sandy soil Q2= л QS1 = л QS Total = 2196 + 732 = 2927 KN QU = 6627 + 2928 = 9555 KN  

25. Design of driven pile in clay soil 25 Use static formula: Length of pile = 25m, Diameter of pile = 50cm, γ =18 , ø = 30 , c = 3.8 t/ Ca =3t / Qb = Ab Cnc Qb = π KN QS= f = C a Qs= л QU=42.529+1178=1220.6KN Qall =1220.6  

26. BORED PILES 26

27. Pile installation Pile installation is as important as design. There are two methods of installation : a)Installation by Driving b)Installation by Boring 27

28. Bored Piles Bored piles is another type of reinforced concrete  piles  which is used to support high building which has heavy vertical load. Bored pile is a cast-in-place concrete pile where the bored piles have to be cast on construction site. 28

29. Bored Piles 29 Normally  bored piling has be to carried on those tall buildings or massive industrial complexes, which require foundations which can bear the load of thousands of tons, most probably in unstable or difficult soil conditions. Bored piling is cast by using bored piling machine which has specially designed drilling tools, buckets and grabs, it’s used to remove the soil and rock. Normally it can be drilling into 50metres depth of soil.

30. Advantage & Disadvantage of Bored Piles 30 Advantage Disadvantage Absence of vibration will not disturb adjacent piles or structures. Susceptible to "wasting" or "necking" in "squeezing" ground. Extremely high capacity caissons can be obtained by expanding the base of the shaft up to three times the shaft diameter, thus eliminating construction of caps over multiple pile groups. Concrete is not placed under ideal conditions and cannot be subsequently inspected. For many design situations bored piles offer higher capacities with potentially better economics than driven piles. Water under artesian pressure may pipe up pile shaft washing out cement.

31. Bored Pile installation 31

32. Bored Pile installation To install a pile you should drill a borehole of a specified diameter and depth. Next the borehole should be filled by fine-aggregated concrete and reinforced with a metal frame of a required cut. So, the bored piles are installed and concreted directly on a site. The diameter varies up to 1500mm and depth - up to 10m or 30 m and more. To increase bearing capacity the piles should be installed with a widening at the bottom of the borehole (a foot of pile). Mostly such types of bored piles are used in situations when there are heavy loads to a foundation and the few compressible soils are deep-seated. 32

33. Bored Pile installation The installation of bored piles is free of dynamic effects to soils and foundations of existing buildings. This main advantage of bored piles is more appreciable during a construction within the urban zone. Moreover this type of foundations allows installing of a pile in any soil; even there are construction waste, remains from the previous structures and boulder and cobble deposits.  33

34. Bored Pile installation Quality control is very important during installation of bored piles. All rigs are equipped with a special computer system to control a pile concreting process. The monitoring piles’ parameters are depth, pressure of concrete mix, concrete volume and shape of piles. 34

35. Design of Bored Piles in sandy soil Ɣ=1.8 t / , ɸ = 25 ˚ , D = 50 cm , L = 18 m Q = 1.8 x 18 = 32.4 t / ɸ = 25˚ – 3˚ = 22 ˚ = 20.27 Bored piles: = 0.7-1.5 , taken =1.1 Concrete material = 0.75 , ɸ = 18.75 ˚   35

36. Design of Bored Piles in sandy soil 266.2 TON = = 88.73 TON   36

37. Design of Bored Piles in c lay soil 37 Ɣ= 1.9t / , C = 3.8 T / , D= 50 cm , L=25m Medium soil =2.5-5 taken =3t/ ɸ = 0 ˚ =5.7  

38. Design of Bored Piles in clay soil 122.06 Ton = =40.69 Ton   38

39. THANK YOU Made by : Ahmed Mohamed Zanaty 9103710 Ahmed Abdullah Negm 9104441 Mohamed Ahmed El Saeid 9103644 Abdelrahman Mohamed 9104286 Ahmed Youssef 9100499 Departure: Construction & Building Course : Foundation Under supervision of: Prof. Adel Belal 39