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pile foundation

1. Classification of Piles The Materials Used The Mode of Transfer of Loads Method of Construction The Use or Function The Displacement of Soil

2. Classification Based on Materials Used 1-Steel Piles ● Pipe piles : can be driven into the ground with their ends open or closed, the pipe piles are filled with concrete after they have been driven. ● rolled steel H-section piles , Wide-flange and I-section steel , H-section piles are usually preferred because their web and flange thicknesses are equal. Usual length: 15 to 60 m Usual loud: 300kN to 1200kN

3. Advantages ● Easy to handle with respect to cutoff and extension to the desired length ● Can stand high driving stresses ● Can penetrate hard layers such as dense gravel and soft rock ● High load-carrying capacity Disadvantages ● Relatively costly ● High level of noise during pile driving . ● Subject to corrosion ● H-piles may be damaged or deflected from the vertical during driving through hard layers or past major obstructions

4. 2- Concrete piles a - precast piles: can be prepared by using ordinary reinforcement , they can be square or octagonal in cross section . The piles are cast to desired lengths and cured before being transported to the work site. Usual length: 10 m to 15 m. Usual loud:300kN to 3000kN Precast piles can also be prestressed by the use of high-strength steel pre-stressing cables. The ultimate strength of these cables is about 1800 MN/m2 Usual length: 10 m to 45 m and maximum length is 60 m. Maximum loud :7500 kN to 8500 kN

5. Advantage Can be subjected to hard driving Corrosion resistant Can be easily combined with a concrete superstructure Disadvantage Difficult to achieve proper cutoff Difficult to transport

6. b) Castin situ piles : are built by making a hole in the ground and then filling it with concrete. These piles may be divided into two broad categories: ( i ) cased (ii) uncased. Both types may have a pedestal at the bottom. i - Cased piles: Usual length: 5 to 15 m and Maximum length is 40 m Usual loud :200 to 500kn and maximum loud 800 kn made by driving a steel casing into the ground with the help of a mandrel placed inside the casing. When the pile reaches the proper depth the mandrel is withdrawn and the casing is filled with concrete. And there are cased piles without a pedestal. and cased pile with a pedestal. (The pedestal is an expanded concrete bulb that is formed by dropping a hammer on fresh concrete.

7. Advantages Relatively cheap Allow for inspection before pouring concrete Easy to extend Disadvantage Difficult to splice after concreting Thin casings may be damaged during driving

8. ii-uncased piles: Usual length: 5 to 15 m and Maximum length is 40m. Usual loud: 300 to 500 kn and Maximum loud 700 kn. uncased piles: are made by first driving the casing to the desired depth and then filling it with fresh concrete. The casing is then gradually withdrawn. There are two types of uncased pile, one with a pedestal and the other without. Advantages Initially economical Can be finished at any elevation Disadvantages Voids may be created if concrete is placed rapidly. Difficult to splice after concreting In soft soils, the sides of the hole may cave in, squeezing the concrete

9. 3-Timber Piles Timber piles are tree trunks that have had their branches and bark carefully trimmed off. the timber should be straight, sound, and without any defects. to avoid damage at the pile tip (bottom) Steel shoes may be used. And avoid damage to the top of the pile, a metal band or a cap may be used, Splicing of timber piles should be avoided, if splicing is necessary, it can be done by using pipe sleeves ,or metal straps and bolts The timber pile is placed at a strong level below the water level. This type of pile foundation lasts for about 30 years. When located above the water table , the piles are subject to attack by insects . The usual length : 5 m to 15 m The maximum length is 40 m, The usual load : 300 kN to 500 kN.

10. advantages Timber piles can stay undamaged indefinitely if they are surrounded by saturated soil. The life of the piles may be increased by treating them with preservatives such as creosote. Disadvantages cannot withstand hard driving stress; Timber pile capacity is generally limited. timber piles may also be damaged during the driving operation. a marine environment, timber piles are subject to attack by various organisms and can be damaged extensively in a few months.

11. 4-Composite Piles The upper and lower portions of composite piles are made of steel and concrete or timber and concrete. This type of pile is used when the length of the pile required for adequate bearing exceeds the capacity of simple cast-in-place concrete piles. forming proper joints between two dissimilar materials is difficult, and for that reason, composite piles are not widely used.

12. Classification Based on Mode of Transfer of Loads End Bearing Piles In this type of pile, the lower end of the pile is lowered into the ground up to the level of strong ground or rock. The load of the structure of the building is transferred to a stronger level by the bearing pile. This type of pile acts as a column. This type of pile transfers the load of the structure from a weak layer to a strong layer .

13. Friction Piles In this type of pile, the load of the building is transferred to a strong soil strata using skin friction along the length of the piles. This type of friction pile transfers the superstructure load of the building to the ground using the force of friction resistance between the surface of the pile and the adjacent ground. These types of pile foundations are commonly known as floating pile foundations.

14. Classification Based on Installation Driven Piles Driven and Cast-in-situ Pile Bored Cast-in-situ Pile Screw Pile Jacked Pile

15. Classification Based on Use Load Bearing Pile Compaction Pile Tension Pile Sheet Pile Fender Pile Anchor Pile

16. Classification Based on Displacement of Pile Displacement Pile Non Displacement Pile