Real and Apparent Relaxation of Driven Piles

Abstract

Relaxation, defined as a decrease in bearing capacity of driven piles with time after initial driving, has been observed to be a rare phenomenon in southern Canadian geotechnical conditions. It has been encountered by the writers with piles driven to end bearing in shale of the Georgian Bay Formation in the Bayfront area of downtown Toronto, Ontario. In this case, the approach of increasing the end area of the piles to reduce the bearing pressure has been counter‐productive. In other founding conditions, a reduction in driving resistance between the end of initial driving and the beginning of redrive has not indicated a reduction in bearing capacity, but rather an increase in the developed force from the pile hammer. It appears to be primarily associated with the use of single‐acting diesel hammers.