A SIMPLE SOLUTION FOR DETERMINING INTERACTION OF PILE-SOIL-PILE IN STATIFIED DEPOSITS UNDER AXIAL HARMONIC VIBRATIONS

In normal foundation construction, piles are used in groups, where the response of the group is influenced by closely spaced piles. This paper contributes to develop a simple efficient, closed form solution to determine the interaction between piles in the group. Initially, the elasto-dynamic approach of Novak and his colleagues is used to simulate an isolated vertical prismatic piles subjected to harmonic axial vibration. An approximate approach based on the interference of cylindrical wave fields originating along each pile shaft and spreading radially outward is then used to model the contribution of closely spaced piles in the group. To this aim, the "Segment by Segment Method, (SSM)” developed initially by the first author is applied to determine the soil inhomogeneity in the vertical direction. The solution offers the stiffness and damping coefficients for the whole pile groups. The results are comparable with those given by rigorous solutions, demonstrating the sound ability of the approach. The main advantage of the solution is its efficiency and simplicity in practical situations, especially for inhomogeneous soil. The results of analyses show the effect of pile-pile distance in the group, excitation frequency, and soil stratification. Finally, interaction factors will be presented for pile group embedded in layered soils. It will be shown that there is no limitation to the number of soil layers in simulation.

Keywords:

Pile group , harmonic vibration , pile-soil-pile interaction , stiffness , damping , segment by segment method