Applied Mechanics and Materials Vols. 405-408

Abstract: For the large coastal harbor with one entrance attacked badly from the waves and sands from the sea, it is advantaged to break waves and produce sands, but not advantaged for the water exchange flux, especially when a point source appearing inside the harbor, the polluted water is difficult to flow into the sea in time and be diluted by the water from outside. The water flow in estuary presents the character of to-and-fro flow, and the polluted source will flow into harbor with the flood tide and pollute the harbor secondly, although it has been outside the harbor at least with the ebb tide. For the harbor with one entrance against waves, the polluted source will be more difficult to be transported to the outside when waves coming, and the water environment capacitance will decline rapidly for the polluted water not to be absorbed. It is Taizhou Wenling harbor for example in Zhejiang province, and the movement of water particle is simulated in tidal current and wave to describe the movement of the point source transported not diffused. The rusults show that the capacity of water exchange for the large harbor wih one entrance will be declined in both tidal current and wave.

Abstract: Offshore jacket platforms under complicated and changeful ocean environments are subjected to various stochastic actions such as actions of wave, current, wind, ice, earthquake and their combinations. This paper presented the approach to calibrate of the reliability of the offshore jacket platform, and suggested all kinds of associated load cases. The combination of loads were mainly investigated. As an example, the reliability of offshore jacket platform of QK18-1 in Bohai Bay was verified. The result shows that the reliability of the offshore jacket platform related to 25-year reference period is between 2.7 and 3.39, which is close to the conclusion of some existing researches. This method would be used more widely for the design of offshore jacket platforms.

Abstract: A three dimensional numerical model to calculate the wave forces on the composite bucket foundation of the offshore wind turbine is established and the analytical method to approximatively calculate wave forces on the structure with the variable cross section is proposed. Based on the validation of numerical results, wave forces on the composite bucket foundation are calculated under different wave conditions. The variable cross-section of the composite bucket foundation is divided into sections with the approximate same diameter. Comparison with the numerical calculations and analytical results, the wave force on each section can be calculated using Morison equation when the relative diameter is less than 0.2 and using diffraction theory when the relative diameter is more than 0.2.

Abstract: Lattice type steel sheet pile wharf is a new type of wharf structure, which is increasingly and widely used, but its structure is complicated, and the calculation theory is not perfect. This paper uses the general finite element software ABAQUS to establish the finite element numerical calculation model of grid shape steel sheet pile structure. The result was deeply researched and analysed,so some useful conclusions are drawn that can be used as references in the engineering application.

Abstract: The article analyses and predicts the hydrodynamic feature of Tang Shan bay on the basis of Ecomsed model, thus the calculation accuracy is improved. And then it predicts erosion-deposition characteristics of the study sea area.The paper assesses the influence of the artificial island construction in aspects of hydrodynamic and erosion-deposition environment. Research shows that the sea area in the north of the artificial island is deposition area because of sand excavation and the water inside is slightly deposit.

Abstract: Caofeidian sand island unique shoal-channel system provides construction conditions for deep-water port.By comparing the underwater topography changes before and after Caofeidian industrial construction to understand the sediment transport and erosion-deposition evolution. Bathymetry results in 2006 and 2012 showed that the deep channel is in good stability. 2 to 3 years later after construction, excepting artificial dredging area, erosion occurs in front of the headland. The sediment is transported to the west of harbor 1 entrance. Seabed sediment controlled by wave comes from the front of the southeast seawall inflection point is transported to the deep channel, some deposits in the east slope and the most is taken away by the deep channel water. All processes above become more weakly now, in the future the sea area in front of the headland will erode weakly, the sea area in the west slope will deposit weakly while in the east slope will erode weakly, and the sea area near the harbor entrance will erode.

Abstract: Based on the essential characteristic of cohesive deposits, from the motion mechanism of cohesive deposits to start with, incipient motion of cohesive deposits laws under different conditions of bulk density and flow are studied by flume experiment. The research results show that the incipient motion of cohesive deposits is greatly influenced by the bulk density. The incipient motion velocity is increase with the growth of bulk density.

Abstract: The effects of ocean waves on the stability of seafloor slopes are of great importance in marine environment. The stability of a seafloor slope considering wave-induced pressure is analyzed using the kinematic approach of limit analysis combined with a strength reduction technique. A seafloor slope without waves is considered first. Furthermore, waved-induced pressure is considered to act on the surface of slope as an external load to analyze the effects on the stability of slope by waves. The results show that the adverse effect of waves on slope stability increases with an increase of the wave height as well as a decrease of the water depth.

Abstract: A nonlinear elliptic mild slope equation was used to simulate the wave transformation in the water of Rizhao harbor. The model is well suited to complex domain, and fits the irregular boundary conveniently. When the incident direction of wave is E, the mooring condition of harbor entrance is poor, and when the incident direction is SE, the wave hights are relatively great in the inside harbor basin. In wave numerical simulation, the physical phenomenon of wave transformation including wave diffraction, refraction and reflection can be shown obviously. The results show that the model could be used on relative large region and get ideal results.

Abstract: A calculation method of rotational stiffness of all-vertical-pile-supported (AVPS) wharf is discussed and a formula based on rotational stiffness is derived to evaluate the distribution of horizontal forces on an AVPS wharf. Combining with an engineering example, the rotational stiffness and the horizontal force distribution coefficients were calculated utilizing finite element method (FEM), the elastic support-rigid beam method (ESRBM) outlined in Chinese Harbor Code, as well as the proposed formula for the piles layout width-length ratio of 0.4, 0.5 and 0.6. Results indicate that the increase in width-length ratio will increase the rotational stiffness and make the distribution of horizontal forces on each bent to be more uniform. Results calculated by the proposed formula are agree well with the results by FEM. The maximum difference of the distribution coefficient on the first bent between the results obtained by the proposed formula and by ESRBM is approximately 22%.