why we use piles in group insted of single pile.

Cause of  using of pile in group :

A pile is not used singulerly benearth the column because it's difficult to drive the pile absolutly verrically and to place a foundation exactly over it's center line.

1. If eccentrically loading acts, the connection b/w thepile and column may bereak and pile may be fail due to bending action.
2. for column minimum three piles are used
3. The super structure ais supported by the several piles as a group
4. the load usually transfered to pile group  the rcc slab or pile cap
5. The load carrying capacity of group pile is not equal to the sum ofcapacity of individual piles
6. the estimation of load carrying capacity in group pile is a complecated problem because when the piles are spaced apart, the group capacity is sum of individual pile capacities.