Application of Particle Image Velocimetry for the Visualization of Soil Deformation Processes due to Cyclic Lateral Loading of Rigid Piles

It is well known that piles embedded in sand accumulate lateral deformation (displacement and rotation) when subjected to horizontal cyclic loading. The rate of accumulation depends on various parameters, such as loading conditions and properties of the pile-soil system. For nearly rigid piles, such as monopile foundations for offshore wind turbines, an essential aspect is the type of loading, which is determined by the ratio of the cyclic minimum load to cyclic maximum load. Several studies have shown that asymmetric two-way loading generally results in larger accumulated pile deformation compared with other types of loading, especially one-way loading with complete unloading in each cycle. This article presents the planning, execution, and evaluation of physical 1g small-scale model tests on the deformation accumulation of laterally loaded rigid piles due to cyclic loading focusing on soil deformations resulting from various cyclic load ratios. To visualize soil deformation fields and rearrangement processes within the soil profiles, particle image velocimetry (PIV) was applied in the tests. The evaluation of the model test results provides insights into varying accumulation rates and highlights the capabilities as well as limitations of PIV. The observations are summarized under the section of findings, which may assist in planning future PIV experiments.