Peripheral Water Pressure Characteristics of Piers under Oblique Flow Conditions

To investigate the impact characteristics of oblique flow on dolphin-type pier structures in mountainous river confluence hubs, the Madao Hub of the Pinglu Canal—a pivotal component of China's Western Land-Sea New Corridor initiative—was examined in this study. Full-scale three-dimensional fluid–structure interaction (FSI) simulations were implemented, with validation against physical model experimental data. The flow characteristics and hydrodynamic pressure distributions around ship-berthing piers impacted by the tailwater flow from the Madao Hub were analyzed. Simulation results of the FSIs were benchmarked against standard empirical formulas. The results revealed that under the project's layout configuration, high-velocity flow propagated predominantly along the left bank, primarily impacting piers 8–10. The maximum positive pressure zone was located near the upstream corner of the most-affected berthing pier. As the flow traversed the pier’s leading edge and impinged upon the sidewalls, the hydrodynamic pressure progressively attenuated, transitioning to negative values at the downstream end of the front face and upstream end of the side face. Comparisons indicated that the predicted values matched well with AS500 and IRS standards, whereas IRC 6 standard underestimated the hydrodynamic forces by 85%–90%. Therefore, the IRC 6 standard requires calibration to enhance its safety factor. This study elucidated the pressure distributions around piers under oblique flow conditions, providing a scientific foundation for structural layout optimization, pier geometry selection, and force analysis of piers near mountain river confluences.