Vortex-induced vibrations and solid-structure impacts of a horizontal flexible pipeline in the vicinity of a bottom wall boundary are experimentally investigated in a water flume. A neutrally-buoyant submerged pipe, with a length-to-diameter ratio of about 87 and fixed end supports, is subject to a shear flow with an oblique angle of 30°. The initial gap-to-diameter ratio between the wall and the pipe is equal to 0.2. A non-intrusive measurement with high-speed cameras is employed to simultaneously capture the space–time varying in-line and cross-flow vibrations in the normal flow reduced velocity range of 3–15 with a maximum Reynolds number of about 2780. Experimental results highlight new pipe equilibrium profiles and modal response branches being significantly broadened due to the wall proximity. Two solid-pipe impact features are discussed, including single-segment and two-segment alternating impacts depending on the dominant oscillation mode of the flexible pipe. Both the response amplitude and frequency increase with the reduced velocity, resulting in a more frequent impact with a greater impact force. A temporal evolution from a single point contact to a segment contact is observed for the two-segment alternating impact. Nevertheless, the lengths of the two contact segments are different as a result of the asymmetric response profile. In all cases, the pipe transversely impacts the bottom wall introducing a perturbation transmission along the pipe, which leads to the multi-mode, multi-frequency and asynchronous in-line and cross-flow oscillations with a 1:1 and 2:1 resonance. Due to a momentum energy consumption, the pipe experiences a slow post-impact bouncing phenomenon, contributing to a longer temporal period of the fluid–pipe interaction with a wall impact.

在水槽中实验研究了底壁边界附近水平柔性管道的涡激振动和固体结构影响。长径比为87左右，端部固定支撑的中性浮力潜管，承受30°斜角的剪切流。壁和管道之间的初始间隙直径比等于 0.2。使用高速相机进行非侵入式测量，同时捕获正常流动降低速度范围 3-15 中时空变化的在线和横向流动振动，最大雷诺数约为 2780。 实验结果突出显示新的管道平衡剖面和模态响应分支由于壁接近而显着加宽。讨论了两个实心管冲击特征，包括单段和两段交替冲击，取决于软管的主要振荡模式。响应幅度和频率都随着速度的降低而增加，从而导致更频繁的冲击和更大的冲击力。对于两段交替撞击，观察到从单点接触到段接触的时间演变。然而，由于不对称响应分布，两个接触段的长度是不同的。在所有情况下，管道横向冲击底壁，沿管道引入扰动传输，导致多模式、多频率和异步在线和错流振荡，具有 1:1 和 2:1 共振. 由于动量能量消耗，管道经历缓慢的冲击后弹跳现象，