Structural

Calculation of Various Types of Pile Foundation and Selection

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Calculation of Pile Foundation

The pile code consists of four parts.They are

Part 1: Concrete piles

Part 2: Timber piles

Part 3: Under reamed piles

Part 4: Load test on piles

Out of these Part 1 consists of four section

Among these Calculation of Pile Foundation ,

Section 1: Driven cast in situ concrete piles.

Section 2: Bored cast in situ concrete piles and

Section 3: Driven precast concrete piles are revised in 2010

Some of the important changes in the code are highlighted as follows:

1. Definitions of various terms have been modified as per the prevailing engineering practice.

2. Minimum grade of concrete to be used in pile foundations has been revised to M25.

3. Design parameters with respect to adhesion factor, earth pressure coefficient, modulus of subgrade reaction, etc, have been revised to make them consistence with the outcome of modern research and construction practices.

4. Minimum dia of bored cat in situ pile have been changed as 450mm based on following parameters:

Clear cover over reinforcement

Cl.6.11.4 50×2 = 100mm

Dia of vertical bar minimum

Cl.6.11.4 12×2 = 24mm

Helical reinforcement minimum

dia Cl.6.11.4 8×2 = 16mm

Clearance for operation of Tremie

Cl.6.11.4 4×20 = 80mm

Dia of Tremie pipe minimum

Cl.8.4 (c) = 200mm

Total dia of pile required

= 420mm say ~ 450mm

5. Provisions for special use of large diameter bored cast in-situ reinforced cement concrete piles in marine structures have been added.

6. Procedures for calculation of bearing capacity, structural capacity, factor of safety, lateral load capacity, overloading, etc, have also been modified to bring them at par with the present practices.

7. Minimum time of curing before handling of precast piles has been modified.

8. Provisions has been made for use of any established dynamic pile driving formulae, instead of recommending any specific formula, to control the pile driving at site, giving due consideration to limitations of various formulae.

Book to Read Pile Design and Construction Practice

Selection of pile foundation:

1. For poor bearing soils such as Soft clay, Medium Clay or any clay etc. under reamed pile foundation with pile cap and grade beam or Bored cast insitu Pile foundation with pile cap may be adopted.

2. For clay soil with G+2F, G+3F, slit+3floors loads, under reamed piles with pile caps connected with grade beams is best suited.

If the hard strata available is at 10m depth, End bearing / Bored cast insitu piles with pile caps may be adopted.This type of foundation is best suited for multi storeyed building also.

3. If the load on foundation is 500KN (say G+2Floor load), Under reamed pile foundation for a depth of 3.5m to 4.50m with pile caps shall be adopted.If the load on foundation is in the range of 2000KN to 3000KN, Bored cast in-situ concrete piles with 6.0m to 20.0m depth with pile caps shall be adopted.

Read More Pile Load Test – Methodology