Analytical Method for Settlement of Axially Loaded Compressible Pile

In the design of pile foundation, settlement rather than the bearing capacity is often the controlling factor. Therefore, foundation settlement should be assessed as accurately as possible. Empirical methods are generally used to determine the settlement of pile foundation. As per IS code: 8009, for point bearing pile group, the pile group is replaced by a fictitious footing at the top of the bearing layer. For friction pile groups, it is assumed that the fictitious footing is at a depth of Dp/3 above the pile tip. In IS code method, settlements happen to be same for both the rigid friction pile and compressible pile groups, whereas settlements in case of compressible pile are higher than those in rigid friction pile. An alternative analytical method is developed for determining the stresses induced in the soil due to the axially loaded friction and compressible pile. The vertical stress coefficients obtained by the method proposed are used to determine the settlements of the axially loaded group of friction and compressible piles. It is found that settlement of compressible pile group obtained by analytical method is 2.5 times that of rigid friction pile group settlement obtained by IS code 8009 method or empirical method.