Pile Foundation In Metro or Flyover Construction

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                               Pile Foundation:

  •      Pile foundation is a type of deep foundation.
  •      It is  done where shallow foundation is not possible because hard rock strata is not available at upper levels of ground.
  •      Load is transferred to ground through skin friction and end bearing reaction.
  •     In this project depth of piles is around 14m and diameter is 1m. But it can be as deep as 50m.
  •      It is very slow and steady process and high accuracy is required.


Methodology:

     1.    After the geotechnical survey is done, Survey Coordinate and Control Points are marked.
2.    Boring is done with pile boring machine/rig machine until hard rock strata is found or as per plan. Depth is known by chain sounding method.
3.    If hard rock is found it is further bored for more 2-3 feets for better end bearing reaction.
4.    Simultaneously steel casing/liner is done while boring so that surrounding soil doesn’t fall and is held in place. It also works as formwork for concreting. Oiling is done on inner surface of liner so that concrete doesn't stick to it. It can later be removed.
5.    Vertical alignment is assured by plumb bob verticality test.Vertical Alignment error should not be more than 1.5%.
6.    Care should be taken of ground water table and testing the bottom soil samples.
7.    Boring is done until mud density is around 1.05 gm/cc and marsh cone viscosity should be around 30-40 seconds.
8.    Prefabricated reinforcement is inserted into the casing with cover of 75mm.
9.    M40 grade concrete is pumped down using trimmy pipe until slurry concrete(mixed with mud and water) comes on top.10
10.                    Curing?? No Curing is required for piles because it remains hydrated as it is not open to atmosphere.

Testing Methods Involved :
●      Concrete testing before concreting
○      Size of aggregate shall not be more than 20mm.
○      Slump required is 150-170mm.
○      Minimum cement content shall not be less than 400 kg/㎥.
●      Dynamic integrity test
●      Cross Hole Sonic Logging Test

IS Code references :
●      IS 2911 Part 1 - Concrete
IS 2911 Part 4 - Tests

Reinforcement Of the Piles Over the Cut-Off Level


Piling is in Progress with the help of Rig Machine

Pile Chipping is in Progress Over the Cut-Off level
(due to the Dense material comes upward automatically during the Concreting)

Location: Mumbai, Maharashtra, India

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