Model tests on horizontal pile-to-pile interaction incorporating local non-linearity and resonance effects

Dynamic experimental studies on horizontal interaction factors for laterally loaded model soil–pile systems subjected to low-to-high amplitude pile head loading are reported, focusing on the effect of dynamics and local non-linearity. Results obtained from dynamic experiments with different amplitudes of harmonic lateral loading on instrumented model soil–pile systems conducted on a shaking table indicate that the resonance of soil–pile system shows a profound impact on the horizontal interaction factors. Furthermore, behavior of the soil–pile system becomes highly non-linear with increasing amplitude of loading, as the extent of local non-linearity around the pile increases. Consequently, group effects cannot be predicted by using established approximate equations based on the assumption of linear viscoelastic behavior. To this end, new semi-empirical equations are proposed for obtaining the horizontal interaction factors, as an extension of available approximate equations to incorporate the local non-linear behavior of soil–pile system for both small and large pile spacings.

► Horizontal pile-to-pile interaction factors are measured experimentally.
► Range of dynamic loads is used to induce low-to-high shear strains in soil.
► Local non-linearity and resonance effects of soil show profound impact on results.
► Existing approximate solutions cannot account for local soil non-linearity.
► Equations for approximation incorporating local soil non-linearity are proposed.