The overlapping displacement fields among closely spaced piles termed as pile-to-pile interactions, increase the overall settlement of pile groups. Resultantly, under static loading, these interactions invariably decrease the group stiffness of piles than the collective stiffnesses of corresponding single piles. Whereas under dynamic loading, the group stiffness may increase or decrease than the cumulative stiffnesses of single piles depending on the loading frequency. As soil exhibits nonlinear behaviour under strong motions, in addition to the consideration for soil nonlinearity to obtain the response of piles, nonlinearity generated at the interface between the soil and pile needs to be appropriately considered as it can significantly change the response of piles. To assess the influence of mentioned nonlinearities on the vertical pile-to-pile interaction factors, a scale model test on closely spaced piles is carried out under 1 g conditions. At very low loading amplitudes wherein soil exhibits close-to-elastic behaviour, the experimental interactions are drastically smaller than those obtained from closed-form solutions assuming soil as an elastic material, highlighting the influence of soil-pile interface nonlinearity. Under higher loading amplitudes, results indicate that the increased nonlinearities strengthen the amplitude dependency of interactions. To minutely assess the effects of soil-pile interface nonlinearity on the response, three-dimensional nonlinear finite element modelling (FEM) is carried out. Results obtained from FEM considering soil and soil-pile interface nonlinearities validate the experimental results well. Whereas, assuming soil as an elastic material leads to a noticeable reduction in interactions due to stiffnesses of neighbouring piles; interactions get further reduced when the number of adjacent piles increases.

密集桩之间的重叠位移场称为桩间相互作用，增加了桩群的整体沉降。结果，在静载荷下，这些相互作用总是使桩的群刚度比相应单桩的集体刚度降低。而在动态加载下，根据加载频率，群刚度可能会比单桩的累积刚度增加或减少。由于土体在强运动下表现出非线性行为，除了考虑土体非线性来获得桩的响应外，还需要适当考虑土与桩交界面处产生的非线性，因为它可以显着改变桩的响应。 G使适应。在非常低的加载幅度下，土壤表现出接近弹性的行为，实验相互作用比从假设土壤为弹性材料的封闭形式解获得的相互作用要小得多，突出了土 - 桩界面非线性的影响。在更高的加载幅度下，结果表明增加的非线性增强了相互作用的幅度依赖性。为了详细评估土桩界面非线性对响应的影响，进行了三维非线性有限元建模 (FEM)。考虑土和土桩界面非线性的有限元法得到的结果很好地验证了实验结果。鉴于假设土壤为弹性材料，由于相邻桩的刚度而导致相互作用显着减少；