Pile Groups In Cohesive Soils The effect of driving piles into cohesive soils (clays and silts) is very different from that of cohesionless soils. It has already been explained that when piles are driven into clay soils, particularly when the soil is soft and sensitive, there will be considerable remolding of the soil. Besides there will be heaving of the soil between the piles since compaction during driving cannot be achieved in soils of such low permeability. There-is every possibility of lifting of the pile during this process of heaving of the soil. Bored piles are, therefore, preferred to driven piles in cohesive soils. In c,ase driven piles are to be used, the following steps should be favored:

1. Piles should be spaced at greater distances apart. 2. Piles should be driven from the center of the group towards the edges, and 3. The rate of driving of each pile should be adjusted as to minimize the development of pore

water pressure.