Motion of Floating Caisson with Extended Bottom Slab under Regular and Irregular Waves

Journal of Marine Science and Engineering

Naoto Nagayama¹  Tomoaki Nakamura²  Yong-Hwan Cho²  Norimi Mizutani²  Yoshinosuke Kurahara³  Masahide Takeda³ 

[1] Department of Civil Engineering and Architecture, Nagoya University, Nagoya 464-8603, Japan;Department of Civil and Environmental Engineering, Nagoya University, Nagoya 464-8603, Japan;Research and Development Center, Toa Corporation, Yokohama 230-0035, Japan;

关键词: caisson;    pitch;    heave;    natural frequency;    regular wave;    irregular wave;   

DOI  :  10.3390/jmse9101129

来源: DOAJ

【 摘 要 】

Floating caissons may oscillate primarily due to ocean waves during towing operations. Reducing the oscillation based on the extension part (footing) of the bottom slab of the caissons can efficiently increase the safety of towing maneuvers. However, the influence of the footing length on the motion of floating caissons has not been adequately studied. This study investigates this topic through hydraulic model experiments and numerical simulations. Experimental results for regular waves show that the rotational motion (pitch) of the caisson around the wave crest direction increases owing to resonance. This suggests that the pitch could be reduced by designing caissons, such that resonance may be prevented along the footing length. In the numerical simulations of irregular waves, the Fourier amplitudes of the heave and pitch show that the footings amplify their low-frequency components and reduce their high-frequency components. Furthermore, the significant total amplitudes of the heave and pitch show a different trend from that of the regular waves observed in the hydraulic model experiments. This suggests that it is essential to examine the motion of a caisson under irregular waves when assessing the effect of footings in an actual marine environment.

【 授权许可】

Unknown