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 (alpha) decreases with increasing loading angle, exhibits a positive correlation with zeta b, and shows a negative correlation with zeta c. These findings advance the understanding of cyclic performance in SFT anchors and offer essential insights for SFT safety evaluations.

Submerged floating tunnels (SFTs) represent a promising innovative transportation infrastructure, offering advantages for crossing long, large, and deep bodies of water in the future. However, critical issues regarding their responses mechanism and technique remain unclear, leading to the absence of constructed SFT prototypes globally. A pier-type SFT (PSFT) is a typical SFT configuration with relatively high stability and safety. This study reviews the progress in PSFT research and discusses critical issues and solutions, including structural design, dynamic response characteristics, and feasibility analysis. Suggestions are provided for future research and applications. PSFTs can be considered as immersed tunnels supported by underwater bridge piers. Although adequate research has been conducted on piers, piles, and tunnel tubes, limited investigations have focused on PSFTs. Existing studies are primarily based on conceptual designs of PSFT, lacking theoretical and experimental investigations. The dynamic response characteristics and progressive collapse mechanism of PSFTs under the influence of waves, currents, and earthquakes are complicated. Scouring and liquefaction can significantly reduce the bearing capacity and alter the dynamic responses of PSFTs. Refined numerical simulations and underwater shaking table tests for PSFTs remain limited. In addition, the performance degradation mechanism and damage evolution process caused by accidental loads, such as impact and explosion, should be emphasized. PSFTs are recommended for broad waters with depths ranging from 30 m to 150 m and lengths larger than 1000 m. Although construction technologies for PSFT components are sufficient and mature, guidelines specifically for PSFTs remain imperative. This highlights the necessity for extensive investigations on PSFTs, considering their mechanism and characteristics under extreme environmental loads.