Wave-induced oblique cyclic load bearing characteristic of suction anchor foundations for submerged floating tunnels: experimental and numerical study

Suction anchor foundations serve as a critical anchoring solution for submerged floating tunnel (SFT) cable systems. In marine environments, these foundations must endure not only static loads but also long-term oblique cyclic loading caused by wave excitation, which can result in soil weakening and a reduction in bearing capacity. This study systematically examines the oblique cyclic bearing behavior of SFT suction anchors using a combined experimental and numerical approach. The results demonstrate that (1) the cyclic load ratio initially increases with increasing wave periods, then decreases, before rising again; (2) displacement accumulation at the mooring point occurs rapidly during the initial wave loading cycles, gradually stabilizing as cycling progresses; (3) during foundation failure, tension redistribution displays asymmetric characteristics, with connected cables experiencing load reduction while adjacent cables are subjected to amplified forces; (4) numerical analyses quantify key parametric relationships, revealing that the weakening coefficient (α) decreases with increasing loading angle, exhibits a positive correlation with ζ_b, and shows a negative correlation with ζ_c. These findings advance the understanding of cyclic performance in SFT anchors and offer essential insights for SFT safety evaluations.