Study on the Stability of Ultra-Small Radius Curved Beam Bracket System in Complex Soft Soil Foundation Environment of Fuli Expressway

Aiming at the construction safety of ultra-small-radius curved beam bracket system under complex soft soil foundation environment， taking the Dazonghu Interchange C-ramp bridge project of Fuli Expressway as the background， the finite element software MIDAS/Civil was used to establish the bracket system model， the stability problem of curved beam bracket system under complex soft soil foundation environment was studied. The influence of uneven settlement of the soft soil foundation， curvature radius of the curved beam， and bracket span， width， and height on the stability of the bracket system was analyzed. The results show that under the influence of uneven settlement of the soft soil foundation， the maximum stresses of the horizontal rods when bracket 1 and 2 lose stability are 82.32 MPa and 127.36 MPa， respectively， and none of the horizontal rods reaches the yield state. The instability of the bracket is caused by the insufficient stiffness of the pole itself. When the concrete of the beam body reaches a certain strength， the buckling load of the bracket increases with the increase of the curvature radius of the curved beam， and the buckling load of the bracket of the 120 m curvature radius increases by 93% compared with that of the 60 m curvature radius. The width and height of the bracket have a great influence on the stability of the bracket. Increasing the lateral width of the bracket and reducing the height of the bracket will improve the stability of the bracket. Compared with the bracket width of 16.5 m， the buckling load of the bracket width of 22.5 m increases by 62.34%. Based on the research results， the sedimentation monitoring was conducted on the bracket system， and on-site monitoring showed that the bracket sedimentation monitoring data were within the specified range， indicating that the bracket method has good feasibility and safety for construction under soft foundation conditions.