Construction Deformation Law and Design Optimization of Locked Steel Pipe Pile Cofferdam on Slope Foundation

Locking steel pipe pile cofferdams are widely used in deepwater bridge foundation construction in China. However, limited studies have examined their deformation characteristics under sloped foundation conditions. This study investigates the construction of a steel pipe pile cofferdam for the Xin'anjiang Bridge foundation in Jiande City, Zhejiang Province. A three-dimensional finite element model of the entire construction process is developed using Midas Civil and validated against on-site measurements. The analysis explores the deformation behavior of the cofferdam during construction and evaluates the effects of foundation inclination, construction techniques, and water flow velocity on lateral deformation. Finally, the deformation of the structure was effectively controlled by reasonably optimizing the size of the retaining structure. The results indicate that: Lateral displacement varies significantly due to differences in constraint conditions; Compared to the layered lowering method, the overall lowering approach mitigates cumulative deformation through the synergistic effect of each layer of purlins; Furthermore, the influence of the foundation inclination on cofferdam stability is more pronounced than that of water flow velocity; By optimizing the size of the maintenance system and balancing deformation control with material efficiency, cofferdam performance can be effectively improved. The findings of this study provide theoretical guidance and practical data for deepwater bridge foundation construction under similar geological conditions.