悬浮隧道考虑竖向弹性约束的子结构模型与涡振响应特性

Substructure model considering vertical elastic constraints vortex-induced vibration response characteristics of submerged floating tunnel

通过将跨内支撑锚索与连接边界条件简化为竖向弹性约束,采用尾流振子考虑均匀流作用下结构的流固耦合效应,研究多跨锚索支撑式悬浮隧道的涡振特性。基于Euler-Bernoulli梁理论建立可考虑跨内/边界竖向支撑刚度对涡振特性产生影响的悬浮隧道管体子结构模型,分析多组跨内锚索支撑刚度与边界约束刚度组合下管体的涡振响应规律。研究结果表明:当两类约束刚度增大、结构固有频率增大时,高阶模态越难以被激发,能有抑制涡振响应的作用;当锚索支撑刚度较小和较大时,靠近端部位置的涡振响应幅值随边界约束刚度的增大而减小,且跨度范围内的涡振响应峰值关于中点对称,当锚索支撑刚度中等且相邻阶次频率相差较大时,管体位移由单一模态主导,当相邻阶次频率接近时,在涡振锁定区间内可观察到由模态耦合所导致的“凹陷”和“凸起”的非线性现象;不同位置之间跨内位移响应的极大值在边界约束刚度较小、较大时分别出现在两端、中点位置。

The vortex-induced vibration(VIV)of the multi-span cable-supported submerged floating tunnel(SFT)was studied by simplifying the intermediate supporting cables and connected boundary conditions as vertical elastic constraints,as well as by using the wake oscillator to consider the fluid-structure interaction of uniform flow.A substructure model for the SFT tube was established based on the Euler-Bernoulli beam theory,which can consider the influence of intermediate/boundary vertical support stiffness on the VIV characteristics.The distribution laws of VIV response of the tube during the combination of multiple stiffness sets for intermediate supporting cables and boundary constraints were analyzed.The results show that the increase of the two types of stiffness has a suppressive effect on the VIV response.The frequency corresponding to the VIV for the greater stiffness is higher,and it is more difficult to excite the higher-order modes.When the intermediate stiffness is small or large,the VIV response amplitudes near the end positions decrease with the increase of boundary stiffness,and the VIV response amplitudes in spanrange are symmetric about the midpoint.When the intermediate stiffness is medium and the difference of two adjacent frequencies is large,the displacement is dominated by a single mode.However,when the two adjacent ones are very close,the nonlinear phenomena of"depression"and"bulge"caused by mode coupling are observed at the VIV locking interval.The maximum displacement for all intermediate positions is respectively located at the ends and midpoint when the boundary stiffness is respectively small and large.