The load distributions of the grouped piles under lateral loads acting from one side of the pile cap could be approximately modeled using the elasticity equations with the assumptions that the underground structure is rigid enough to sustain the loads, and only small deformations of the soils are yielded. Variations of the soil-pile interactions along the depths are therefore negligible for simplicity. This paper presents the analytical modeling using the dynamic pile-to-pile interaction factors for 2×2 and 2×3 grouped piles. The results were found comparative to the experimental and numerical results of other studies. Similar to others’ finding, it was shown that the leading pile could carry more static loads than the trailing pile does. For the piles in the perpendicular direction with the static load, the loads would distribute symmetrically with the centerline whereas the middle pile always sustains the smallest load. For steady-state loads with operating frequencies up to 30 Hz, the pile load distributions would vary significantly with the frequencies. It is interesting to know that designing the pile foundation needs to be cautioned for steady state vibrations as the problem of machine foundation. However for transient loads or any harmonic loads acting upon relatively higher frequencies, the pile loads could be regarded as uniformly distributed. It is hoped that the numerical results of this paper could be helpful to the design practice of pile foundation.
International Journal for Numerical and Analytical Methods in Geomechanics 33(2), pp.173-191