In general, a pile group foundation may be subjected to simultaneous axial load, lateral load, moment, and possibly, tortional load from the superstructure. This paper presents the method of analysis for the elastic behavior of pile group foundation under the above combined load. In the proposed method, Mindlin's solutions were applied to express the interaction phenomena between piles, assuming the soil as a homogeneous elastic continuum, and a solution was derived from imposing compatibility between the displacements of the pile and the adjecent soil along each divided element of the piles.
In order to examine the effects of pile spacing, pile arrangement, difference between loadings at center and eccentric point of the pile cap, and so forth on the behavior of pile group foundation, three numerical examples were analyzed. And then, the comparison between the results of the full scale pile group test in the field and the theoretical ones was also made.