Analysis of the Effect of Local Foundation Scouring on the Structural Dynamic Effect of a Cable-Stayed Bridge Across The Sea

The foundation scour reduces the restraining effect of the foundation on the bridge foundation, resulting in the reduction of the lateral bearing capacity of the bridge foundation. For the cross-sea bridge, the dynamic effect of foundation scour on the bridge structure is more significant, thus affecting the safety of the structure. In this paper, the maximum possible local scouring depth of the foundation is first calculated to make the simulated foundation scouring condition conform. to the actual project. Then, the m-method is adopted to calculate the stiffness value of the foundation soil spring and establish an elastic restraint model that reflects the restraint of the foundation soil on the bridge foundation, thus setting up the finite element model of the bridge with regard to the foundation scouring. On this basis, taking Qiongzhou Strait cross-sea highway and railway dual-purpose cable-stayed bridge as an example, the effect of foundation scour on the dynamic effect of cross-sea cable-stayed bridges under the action of wind and waves is analyzed, and the influence law of the local scour depth of the foundation on the dynamic effect of the structure is determined. The maximum scour depth of 12m is considered to increase the displacement of the top of the tower by 14. 65%, mainly because the foundation scours reduces the restraint effect of the foundation soil on the bridge foundation, resulting in the reduction of the lateral bearing capacity of the bridge foundation. Therefore, for the cross-sea cable-stayed bridge without foundation soil treatment, the detection and monitoring of foundation scour should be strengthened or the preventive maintenance and reinforcement treatment of foundation soil should be done in advance to ensure the safe operation of the bridge structure.