南海北部陆坡内孤立波对桩柱作用力的极值推算  

Calculation of the Maximal Force Exerted by Internal Solitary Waves on Piles in Slope Area of the Northern South China Sea

作　　者：谢华荣 熊学军 陈亮 XIE Hua-rong;XIONG Xue-jun;CHEN Liang(First Institute of Oceanography, MNR, Qingdao 266061, China;Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China;College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China)

机构地区：[1]自然资源部第一海洋研究所,山东青岛266061 [2]青岛海洋科学与技术试点国家实验室,山东青岛266237 [3]中国海洋大学海洋与大气学院,山东青岛266100

出　　处：《海洋科学进展》2019年第2期171-186,共16页Advances in Marine Science

基　　金：国家科技重大专项科研任务--南海北部内波流监测;预报;预警系统研究及应用(2016ZX 05057015);国家自然科学基金项目--黄海暖流的多时相特征及其发生机制研究(41376038)和双LADCP深水大洋测量及资料后处理技术研究(41806123);国家自然科学基金青年基金项目--东海黑潮三维结构及季节变化研究(40406009);国家自然科学基金委员会-山东省人民政府联合资助海洋科学研究中心项目--海洋环境动力学和数值模拟(U1606405);国家海洋局全球变化与海气相互作用专项子课题--黑潮不稳定性及多核结构(GASI-IPOVAI-01-05)和东印度洋南部水体综合调查夏季航次(GASI-02-IND-STSsum)

摘　　要：内孤立波的发生常伴随着大振幅波动和突发性强流,对桩柱等海中结构物产生强烈破坏作用。基于KdV方程和Morison公式,在忽略高阶模态的情况下,探讨内孤立波对桩柱的单位作用力、总作用力、剪力和弯矩的极值问题,并利用2016-07南海北部陆坡的实测资料对理论结果进行检验。结果表明:1)在内孤立波最大振幅所在的垂向剖面上,上层与下层各存在一个单位作用力极值,且二者方向相反,上层总作用力强于下层,最大剪力和弯矩分别发生于水平流速的转向层和海底;2)各水层中,沿着内孤立波的传播方向,所有作用力的数值均随时间的推移先递增后递减,存在正向或负向的最大值;3)全水层总作用力极值发生在半周期,其值与波动振幅和水平波速有关,其他作用力极值发生于最大振幅时刻之前,作用力极值与振幅和非线性波速正相关,与水平特征宽度负相关;4)单位作用力极值的时间提前量与振幅和水平特征宽度强相关,与非线性波速弱相关。The fast oscillation of strong current associated with internal solitary waves (ISWs) can cause severe threat to the structures in sea water like piles.In this paper, maximal values of unit force, total force, shear force and bending moment exerted by ISWs on pile are obtained using KdV equation and Morison's empirical formula with higher modes neglected.The theoretical results are verified with the mooring observations in slope region of the Northern South China Sea during July 2016.It is found that, when the soliton reaches its trough, two maxima of unit force with opposite direction occur in upper and lower layers, respectively.The total force in the upper layer is stronger than that in the lower layer.The shear force is largest at the demarcation depth of horizontal velocity induced by ISWs.While the bending moment is largest at seafloor.In the propagation direction of ISWs, all forces increase first then decrease and have a maximum positive or negative value.Maximal total force occurs at semi-period of ISWs and is related to the amplitude and nonlinear phase speed of the ISWs.The other forces reach their maxima before the trough arrives, and are positively correlated with amplitude and nonlinear phase speed, but negatively correlated with horizontal characteristic scale.Lead time of maximal unit force is tightly correlated with amplitude and horizontal characteristic scale, but weakly correlated with nonlinear phase speed.

关 键 词：内孤立波 桩柱 作用力 KDV方程 Morison公式 

分 类 号：P731[天文地球—海洋科学]