In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environ...In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.展开更多
The seabed scouring and silting are very important to the construction of port and waterway engineering. Seabed deposition and erosion change is complicated due to the influence of sediment supply, human activities an...The seabed scouring and silting are very important to the construction of port and waterway engineering. Seabed deposition and erosion change is complicated due to the influence of sediment supply, human activities and other factors. The Yangshan Deepwater Port is the new deep water harbor, which is an important part of the Shanghai International Shipping Service Center. Its construction has received much attention. At present, the water depth from the 1 st to the 3 rd harbor district is currently suitable under regular dredging and tidal current action. The fourth harbor district will be built in the world’s largest fully-automated deep water wharf. In the study, bathymetry change of the entire sea area of the Yangshan Deepwater Port and the 4 th harbor district(i.e.,Phase IV project) waters were analyzed quantitatively using multiyear bathymetric, hydrological and sediment data. The results show that from 1998 to 2010, seabed changes are characterized by large volumes of erosion and sedimentation, which the southern part was deposited and the northern part was eroded in the inner harbor waters, but the seabed of the Kezhushan inlet was eroded. Seabed changes of Phase IV project waters generally show a scour tendency in recent few years with the annual scour rate about 0.7 m. Among the many factors, the existence of Kezhushan inlet and its influence of the western water flow play an important positive role in water depth changes under the ebb tide action.展开更多
The numerical modeling of a 2D flow around a horizontal cylinder near a rigid bed with the gap ratios G/D = 0, 0.2, 0.3 at Reynolds numbers 840, 4500, 9000, and 9500 is investigated by using weakly compressible smooth...The numerical modeling of a 2D flow around a horizontal cylinder near a rigid bed with the gap ratios G/D = 0, 0.2, 0.3 at Reynolds numbers 840, 4500, 9000, and 9500 is investigated by using weakly compressible smoothed particle hydrodynamics. The velocity field and the separation angles from the present simulations are compared with those obtained from the experimental measurements and are in a good agreement. The results show that the maximum value of shear stress on the bed increases as the cylinder closes the bed and suddenly decreases when the cylinder contact the wall.展开更多
基金The National Natural Science Foundation of China under contract Nos 41402253,41427803 and 41372287the Project of Qingdao National Laboratory for Marine Science and Technology under contract No.QNLM2016ORP0110
文摘In estuarine and coastal areas, the seabed is in a constant process of dynamic change under marine conditions.Seabed sediment erosion and resuspension are important processes that safely control the geological environment. Field tripod observations conducted in the Jiaozhou Bay in China are reported, to investigate the effects of hydrodynamic conditions on the erosion and resuspension processes of the seabed. The observational results show that the maximum shear stress created by tidal currents can reach 0.35 N/m2, which is higher than the wave-induced shear stress during fair weather conditions. A seabed erosion frequently occurs during the flood tide, whereas a seabed deposition occurs during ebb tide. Waves can produce a bottom shear stress approximately equivalent to that induced by currents when the local wind reaches Force 4 with a speed of 5 m/s.When the wind reaches 7 m/s and the significant wave height reaches 26 cm, waves play a more significant role than currents in the dynamic processes of the seabed sediment resuspension and lead to a high value of turbidity that is approximately two to eight times higher than that in fair weather. These analyses clearly illustrate that periodic current-induced sediment erosion and resuspension are dominant in fair weather, whereas episodic high waves are responsible for significant sediment resuspension. Additional work is needed to establish a more thorough understanding of the mechanisms of sediment dynamics in the Jiaozhou Bay.
基金The Fund of Tianjin Research Institute of Water Transport Engineering of China under contract Nos TKS180101,TKS170202 and TKS150207the National Natural Science Foundation of China under contract Nos 51509120 and 51779112+1 种基金the Shanghai Science and Technology Committee under contract No.15DZ1202300the Tianjin Science and Technology Plan Innovation Platform and Talent Special Fund Project under contract No.16PTSYJC00190
文摘The seabed scouring and silting are very important to the construction of port and waterway engineering. Seabed deposition and erosion change is complicated due to the influence of sediment supply, human activities and other factors. The Yangshan Deepwater Port is the new deep water harbor, which is an important part of the Shanghai International Shipping Service Center. Its construction has received much attention. At present, the water depth from the 1 st to the 3 rd harbor district is currently suitable under regular dredging and tidal current action. The fourth harbor district will be built in the world’s largest fully-automated deep water wharf. In the study, bathymetry change of the entire sea area of the Yangshan Deepwater Port and the 4 th harbor district(i.e.,Phase IV project) waters were analyzed quantitatively using multiyear bathymetric, hydrological and sediment data. The results show that from 1998 to 2010, seabed changes are characterized by large volumes of erosion and sedimentation, which the southern part was deposited and the northern part was eroded in the inner harbor waters, but the seabed of the Kezhushan inlet was eroded. Seabed changes of Phase IV project waters generally show a scour tendency in recent few years with the annual scour rate about 0.7 m. Among the many factors, the existence of Kezhushan inlet and its influence of the western water flow play an important positive role in water depth changes under the ebb tide action.
文摘The numerical modeling of a 2D flow around a horizontal cylinder near a rigid bed with the gap ratios G/D = 0, 0.2, 0.3 at Reynolds numbers 840, 4500, 9000, and 9500 is investigated by using weakly compressible smoothed particle hydrodynamics. The velocity field and the separation angles from the present simulations are compared with those obtained from the experimental measurements and are in a good agreement. The results show that the maximum value of shear stress on the bed increases as the cylinder closes the bed and suddenly decreases when the cylinder contact the wall.
