Vibration Behavior Analysis of Anchor Cables in Submerged Floating Tunnel and Its Application

Based on the vibration mechanism of the anchor cable of submerged floating tunnel (SFT) in water, the partial differential equation of the anchor cable’s vibration with wave and uniform flow is derived. According to the simply supported boundary condition and the difficulty of solving the partial differential equation, the numerical solution is given by Galerkin method and Runge–Kutta method. Taking the design of SFT in Qiandao Lake as the engineering background, the responses of anchor cable vibration are analyzed and studied. The method of measuring and calculating anchor cable force in water is proposed. The results show that when the vortex-induced shedding frequency is close to the natural frequency of the first order of the anchor cable under the action of uniform flow, the cable will produce the corresponding vibration. At this time, the vibration response of the cable displacement arrives to the maximum. Although the third and fifth modes only account for about 1% of the displacement response, their influence on the dynamic bending moment and shear force of the anchor cable can reach 10%. With the same parameters of anchor cable, the vibration frequency of anchor cable in water is lower than that in air, and the difference increases with the increase of anchor cable force. The quadratic function between cable force and frequency of anchor cable in Qiandao Lake SFT is fitted, which can directly guide the monitoring of cable forces of SFT.