Mechanical Behavior of Anti-Floating Anchors Under Cyclic Loading Considering Interface Degradation

Under cyclic loading, anchorage interfaces in anti-floating anchors may degrade, weakening bond strength and reducing bearing capacity, thereby compromising structural safety. Accordingly, understanding the mechanical behavior of anti-floating anchors while accounting for interface degradation is essential for ensuring the safety of underground structures. This study employs an elastic–plastic shear stress–shear displacement model that incorporates cyclic interface degradation, in which the degradation of interface strength and stiffness is governed by the number of loading cycles and the cyclic degradation parameters. By combining the load transfer method with the finite difference method, a mechanical analysis framework was developed for anti-floating anchors subjected to cyclic loading. The model was validated against published experimental data and then used to investigate interface stress distributions, load transfer mechanisms, and the effects of the number of loading cycles, load amplitude, and mean load. The results show that (1) under initial loading, the stress distribution along the anchoring interface progressively shifts toward the anchor tip as the load increases; (2) under cyclic loading, the bearing capacity of anti-floating anchors decreases continuously with increasing cycle numbers and stabilizes after reaching a certain number of cycles; (3) different initial interface strengths significantly influence the load transfer mechanism. High-strength interfaces can complete load transfer within a shorter anchorage length with more concentrated stress distribution, while low-strength interfaces enter the stable degradation stage earlier with more uniform stress distribution. The cyclic degradation parameter determines the degradation process and ultimate strength state of the interface. These findings provide practical guidance for controlling the long-term uplift deformation of underground structures, thereby helping to reduce the risk of basement upheaval and structural cracking in coastal environments with high groundwater levels.