深水半潜式平台运动响应及截面波浪载荷模型实验研究

半潜平台在恶劣的海洋环境中将承受极端的环境载荷,从而导致相应的大幅运动,截面载荷以及系泊力。文章对一艘系泊在南海的典型半潜平台进行了综合试验研究。为了测量中纵剖面上的波浪载荷,半潜平台模型从中纵剖面处被剖开,并用3个六分力传感器进行连接。结果表明,当波浪周期在10 s附近时,中纵剖面处的截面传递函数达到最大值。而低频长波以及差频波浪成分对剖面载荷影响很小。文中还分别针对仅有波浪作用的海况和风、浪、流联合作用的海况,对半潜平台的运动和载荷情况进行了研究,发现风和流对平台波频运动影响较小,而对于低频运动,其影响要大于波浪作用。随着风和流的出现,中纵剖面的剪切力,分离力以及垂向弯矩增幅分别可达127.07%,51.87%和45.77%。与此同时,在风、浪、流的联合作用下,最大锚链力与锚链的破断强度比值达到了62.3%,接近规范中66.6%的限制。

Experimental Investigation on Motion Responses and Sectional Wave Loads of a Moored Semi-submersible in Deepwater

The semi-submersibles are extensively employed in the offshore production but often suf-fer from extreme motion responses, internal sectional loads and mooring line tensions in harsh envi-ronments. A comprehensive experimental study was carried out to investigate the performance of a typical semi-submersible moored in South China Sea. In order to measure the wave loads in the lon-gitudinal mid-section, the semi model was divided into two parts. Three six-component force sen-sors were assembled to connect the two parts. It is revealed that the wave load transfer functions in the longitudinal mid-section reach to their peaks at the wave period of 10 s and the low-frequency long waves and the difference frequency waves seem to have little influence on the sectional loads. The influence of the wave and the combination of wave, wind and current was figured out by a com-parative study. It is noted that the wind and current have little influence on the wave-frequency mo-tions. But for the low-frequency motions, the contribution of the wind and current outweighs that of the wave. With the appearance of the wind and current, the maximum shear force, the separation force and the vertical bending moment in the longitudinal mid-section increase 127.07%, 51.87% and 45.77%, respectively. Meanwhile, the ratio (maximum mooring line tension/broken strength) reaches up to 62.3% in the most loaded line, which almost exceeds the limitation of 66.6%.