水中悬浮隧道锚索的非线性涡激振动研究

Research on Nonlinear Vortex-induced Vibrations of Submerged Floating Tunnel Tethers

建立了水中悬浮隧道锚索在波流场中涡激振动的非线性数学模型,考虑了锚索的几何非线性对其涡激振动的影响,并应用有限差分法求解了锚索的运动控制方程。计算结果表明:锚索在顺流向和横向2个方向运动的耦合作用特别是几何非线性作用的引入,抑制了部分高阶模态的激发,使锚索横向涡激振动的振幅减小,顺流向振动的振幅增大;在悬浮隧道的振动引起的强迫激励和参数激励作用下,锚索顺流向涡激振动振幅显著增大,横向涡激振动出现"拍"的现象。

Mathematical model of nonlinear vortex-induced vibration was presented for predicting the nonlinear dynamic responses of submerged floating tunnel （SFT） tethers which were subjected to wave, current and oscillatory displacements at their upper end in horizontal and vertical directions. The finite difference method was used to solve the dynamic equations of tethers. The calculated results show that the transverse amplitudes of vortex-induced vibration decrease when considering the coupling between the in-line and the cross-flow vibrations. The geometric nonlinearity of the tether inhibits the excitement of higher modes of vibration. However, the in-line amplitudes of vortex-induced vibration increase due to the coupled vibrations. Periodical vibrations of submerged floating tunnel caused by wave forces play the roles of parametric exciter and forcing exciter to vortex-induced vibrations of tethers. In-line amplitudes of vortex-induced vibration increase obviously due to the external excitations, and the transverse amplitudes of vortex-induced vibration exhibit a periodic behavior. These results indicate that the higher modes of vibration are excited because of external excitations.