The influence of clayey soil hardpan layers in turbid plumes from water flow

To investigate the formation mechanism of hardpan layers in liquefied silty soils, this study simulates external physical disturbances using a controllable rotating wheel and observes the internal flow field evolution through Particle Image Velocimetry (PIV) experiments. The objectives are to analyze the flow field structure, soil microstructure, and basic geotechnical parameters under varying disturbance intensities. Results show the emergence of two distinct flow velocity centers during liquefaction: Center A, where upward seepage drives fine particles from the bottom, and Center B, associated with high pore pressure beneath the disturbance source-both critical to soil skeleton rearrangement and liquefaction. Microscopic imaging (500×) and index tests reveal that increasing disturbance intensity leads to skeleton coarsening, directional rearrangement, and compaction of deeper layers. These findings clarify the liquefaction-seepage mechanism driving hardpan formation and provide insight into microstructural evolution under hydrodynamic disturbance.