Study Of The Harbor Water Resonance In Dayaowan Harbor Of Dalian

Dayaowan waters are narrow and long, especially bottom waters are more narrow. The waters of the harbor connect with the open sea only by the south and north channels. Already built berths are mostly the gravity caissons (total reflection boundarys). When the waves come from the open sea to dayaowan harbor by the entrances, the underwater topography and morphology of harbor shoreline would induce refraction and (multiple) reflecting as well as wave energy dissipation is difficult. The above factors are predisposing factors of harbor resonance. Will dayaowan harbor happen water resonance and how the conditions and the strength occured and other problems are the key issues in the development of the whole planning. This paper uses the Boussinesq numerical wave model to solve the questions above.Firstly, simulating the surface responses of the whole water in the harbor to an incident white noise by the improved Boussinesq numerical wave model. The natural frequencies of different areas in dayaowan harbor are estimated by comparing the amplitude spectrums obtained from spectral analysis with the theoretical values of amplification factors.The surface responses of the whole water to incident monochromatic (regular) and random waves are simulated and the numerical results show the response of different areas in dayaowan harbor are markedly different to the same incident wave. Therefore, regarding the local water areas where are easy to be stimulated drastic fluctuations such as in the bottom of the harbor and in the small harbor in the south bank as the independent smaller harbors in dayaowan harbor. Analysing the characteristics of the water resonance in the local areas and the whole harbor from the history of wave elevation, amplitude spectrums and wavelet spectrums. The studies show:1.Under the action of unimodal spectrum waves, the whole harbor water resonance is stimulated by the incident wave with the period of60s, which is much larger than the period of the local offshore waves; The water resonances in the bottom and in the small harbor in the south bank of the harbor are stimulated by the incident wave with the minimum period of11～13s, which are close to the period of the local offshore waves. In consequence, the water resonances are probabily in the bottom and in the small harbor in the south bank, but not in the whole harbor waters.2.Under the action of bimodal spectrum random waves, having a stronger role in amplitude on the water resonance compared with the unimodal spectrum wave with the same spectral energy and the low spectrum peak frequency. 3.Proposed five improvement schemes in view of the local water areas in the bottom of the harbor and in the small harbor in the south bank where are easy to be induced local water resonances. The simulation results show that, decreasing the reflection coefficient of the borders is effective to prevent the water resonance in the local waters; Reserving800m X600m water in the region of the north shore near28#-29#berths is effective to reduce the water resonance in the bottom. In addition, the two programs play important roles in improving the whole water surface stable level.