AbstractFor this study, a scaled model test is conducted to investigate the deflection of a laterally loaded pile and soil deformation in loose sand. An optical experimental setup is developed to capture images of soil movement and the readings of strain gauges along the pile. The deflection of the pile, derived from readings of the strain gauges, increases with the increasing lateral loads. Additionally, the displacement fields of ground surface and profile from a series of images are calculated using the particle image velocimetry (PIV) technique. This technique provides a more accurate estimate of the pile deflection compared with the double integration (DI) method. The images illustrate that the sand rotated in a position approximately 160 mm deep, which is identical to the results of the DI method. Finite-element analysis is used to simulate the model test, which verifies the accuracy of the PIV technique. The results demonstrate that the PIV technique and this optical setup are suitable for solving ...