A general three-dimensional boundary integral formulation for pile groups is used to obtain
a set of dynamic interaction factors for a number of soil profiles and for a wide range of pile
and soil parameters. The formulation employs the Green's functions for barrel loads and disk
loads in layered semi-infinite media to couple the dynamic response of the soil mass to that
of the piles by invoking the equilibrium and compatibility requirements. The interaction
factors presented in this paper can be used in conjunction with the superposition method.....