Centrifuge Modeling of Wave–Seabed–Pipe Interaction in Clay

This study investigates wave-induced seabed instability in clayey soils and its impact on the pipe–soil interaction for pipelines or tunnels through centrifuge modeling. An inflight wave-generating device was developed to achieve stable wave generation at 50g, effectively simulating prototype conditions including 15-m water depths, 4.1-m wave heights, and 25-m seabed thickness. A series of tests were conducted on seabeds with different consolidation states, incorporating sequential wave loading–reconsolidation cycles to examine pore pressure evolution, shear strength degradation, and soil–pipe interaction. Key findings reveal that clayey seabeds exhibit pronounced pore pressure accumulation even under low-intensity waves, with instability triggered by dynamic strength degradation rather than excess pore pressure reaching nominal effective stress—establishing a distinct mechanism from sand liquefaction. The normally consolidated seabed gains substantial strength post-reconsolidation, while the overconsolidated one undergoes stress release and structural weakening, exacerbating vulnerability to subsequent wave loadings even after reconsolidation. Nevertheless, both seabed types develop interlayers that exhibit a sharp strength increase relative to adjacent depths, and these layers spatially align with oscillatory failure boundaries. The presence of pipe amplifies pore pressure accumulation under waves, while significantly inhibiting dissipation during reconsolidation.