Load Carrying Capacity of Bored Cast In-situ Concrete Pile in Cohesive Soil -(IS-2911-Part1-Sec2-2010)

As per IS-2911-Part1 / Sec-2, the ultimate load carrying capacity (Qu) of pile in cohesive soils is given by the given below, where the first term represents the end bearing resistance(Qb) and the second term gives the skin friction resistance(Qs).

pile load capacity in cohesive soil
pile load capacity in cohesive soil

 

pile in cohesive formula
pile in cohesive soil formula

Where,

Qu = Utimate load capacity, kN

Ap = Cross-sectional area of pile tip, in m2

Nc = Bearing capacity factor, may be taken as 9

αi = Adhesion factor for the ith layer depending on the consistency of soil. It depends upon the undrained shear strength of soil and may be obtained from the figure given below.

Variation of alpha with cohesion
Variation of alpha with cohesion

ci = Average cohesion for the ith layer, in kN/m2

Asi = Surface area of pile shaft in the ith layer, in m2

A minimum factor of safety of 2.5 is used to arrive at the safe pile capacity(Qsafe) from ultimate load capacity (Qu).

Qsafe = Qu/2.5

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