The numerical investigation of regular waves interacting with a submerged horizontal twin-plate breakwater is presented in this paper. A numerical model with an absorbing wave-maker is established based on the VOF method. The validity of the model is verified by experimental results. Comparisons between the numerical and experimental results show that both the water surface profiles and the wave-induced pressures can be modeled accurately. Wave deformation over the breakwater,water particle velocities around the breakwater,and the wave-induced pressures on the structure are numerically investigated. The pressure amplitudes of the fundamental and second harmonics on the model surface are examined in various water depths. The computed and experimental results have revealed that the higher frequency components are generated at the onshore side of the breakwater. Furthermore,the computed results demonstrate a circulating flow formed at the onshore side of the breakwater.
For the abnormal ice condition in 2009–2010 winter,sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay,and ice specimens were prepared.Experimental study was carried out with a temperature-control precision of 0.1°C,and 117 columnar-grained ice specimens were loaded along the direction parallel to ice surface under different test temperatures(-4,-7,-10,-13,-16°C)and strain rates ranging from 10-6 to 10-2 s-1 within which the ductile region,ductile-brittle transition and brittle region are contained.The uniaxial compressive strengths,density and salinity of the ice specimens were measured.The results support the curved-surface relationship between the uniaxial compressive strength and porosity within a wide range of strain rate.The curved-surface relationship gives a quantitative description about the variations of the mechanical behavior transition point with ice porosity,and supplies a uniform mathematical representation of uniaxial compressive strength under different failure modes.Besides,it is deduced that abnormal ice condition in 2009–2010 winter will not result in a change of the uniaxial compressive strength of sea ice in Bohai Sea.
LI ZhiJunZHANG LiMinLU PengMatti LEPPARANTALI GuangWei
The wave transmission characteristics and wave induced pressures on twin plate breakwater are investigated experimentally in regular and random waves.A total of twenty pressure transducers are fixed on four surfaces of twin plate to measure the wave induced dynamic pressures.The spatial distribution of dynamic wave pressure is given along the surface of the twin plate.The uplift wave force obtained by integrating the hydrodynamic pressure along the structure is presented.Discussed are the influence of different incident wave parameters including the relative plate width B /L,relative wave height /i H a and relative submergence depth s /a on the non-dimensional dynamic wave pressures and total wave forces.From the investigation,it is found that the optimum transmission coefficient,t K occurs around B /L 0.41 ~ 0.43,and the twin plate breakwater is more effective in different water depths.The maximum of pressure ratio decreases from 1.8 to 1.1 when the relative submergence depth of top plate is increased from 0.8to +0.8.
