Structural Safety Analysis of Steel-Concrete Composite Single-Wall Caisson Cofferdams for Deep-Water Bridge Piers

Under the influence of complex dynamic water conditions, steel–concrete composite single-wall caisson cofferdams may undergo bottom sealing concrete leakage, internal support instability, and even collapse. Therefore, it is necessary to conduct structural stress analyses for single-wall caisson cofferdams under dynamic loading conditions. Using Midas Civil software, finite element models were established for each construction stage of the deep-water pier cap of Dongwuyang Grand Bridge. The stress conditions of the cofferdam, bottom sealing concrete, and cast pier cap were analyzed. The results reveal that the stress in all parts of the cofferdam structure and cast pier cap satisfy the standard requirements, and the design plan is feasible. However, the area with the most severe deformation is the internal support region in the middle of the cofferdam, where the deformation reaches 44 mm. The maximum combined stress is 141 MPa, occurring at the vertical rib location. Local reinforcement should be applied to the internal support and vertical rib areas. During construction, the risks of lifting injuries and drowning are higher than 70 points, identifying these as critical areas for cofferdam construction control.