Abstract: Using a self-developed cyclic loading system, the model tests were conducted to investigate the bearing performance of helical anchor piles under horizontal cyclic loading and the influencing factors of soil deformation. Combined with the particle image velocimetry (PIV) technology, the deformation field of the soil around the pile was analyzed, revealing the deformation mechanisms of the surrounding soil under different influencing factors. The results show that: (1) The amplitude and frequency of cyclic loading significantly influence the bearing behavior of helical anchor piles under cyclic loading. Compared to the original static loading scenario, the bearing performance of anchor piles in dense sand exhibits a decreasing trend when subjected to static loading after cyclic loading. (2) The hysteresis loop evolves from an open to a progressively closed shape, with a clear positive offset in the overall response. Under the same cyclic period, the hysteresis loop area increases with amplitude and decreases with frequency. (3) A predictive model for horizontal cyclic cumulative displacement of anchor piles was proposed based on the law of horizontal cumulative displacement, demonstrating satisfactory predictive performance. (4) The embedment ratio, relative density, amplitude, frequency and period of cyclic load have important effects on soil deformation around the pile. The passive displacement field in front of the pile is most sensitive to the loading amplitude, while sand displacement behind the pile is more sensitive to relative density. The shear field in sand is usually parallel and symmetrical with the axis of anchor pile, and the shear strength is positively correlated with the amplitude and frequency of cyclic load, and negatively correlated with the frequency of cyclic load.

Key words: horizontal cyclic loading, helical anchor pile, model test, particle image velocimetry technology