Experimental investigations of sediment suspended by internal solitary waves under the influence of seepage

REN Ziyin; TIAN Zhuangcai; JIA Yonggang; CHEN Tian

doi:10.13984/j.cnki.cn37-1141.2024.05.002

Abstract：Current researches on the resuspension process of marine sediments were mainly divided into two aspects:the dynamic action of marine fluids and the dynamic response process of sediments under the dynamic action.Internal solitary waves can move hundreds of meters between oceanographic ther-mocline,which not only has horizontal flow,but also can induce extremely strong vertical flow,which further causes the migration of sediment and pollutants.Therefore,the phenomenon of sediment resus-pitation caused by the internal solitary waves shoaling and propagating on the slope has attracted much attention.With the flume experiment based on the researches,the setting up sediment slope and sedi-ment layer in the control group,with controlling seepage condition,controlled the dynamic response of seabed sediment.By making the concave type internal solitary waves,the changing of sediment grain-size composition and internal solitary wave amplitude,comparison and analysis of different internal sol-itary wave under the condition of shallow broken cause of sediment resuspension phenomenon,were discussed about the influence of the dynamic response process of resuspension of sediments.The main research results were found that under the action of internal solitary waves,the faster the flow rate was,the faster the sediment suspended matter concentration changed;and the increased value of sus-pended matter concentration presented a positive correlation trend.For sediment slope area,with seep-age conditions under the action of internal solitary wave could sustain high suspended sediments concen-tration for a longer time;the duration of continuous change was obviously longer than that of sediment layer.And with the slower velocity,slope area after achieving the highest suspended sediment concen-tration,concentration change rate was less than the sediment layer.For sediments with different grain-size composition,with the more clay content,the response speed to the internal solitary waves became more slowly,and the specific variation law was also different.When sediment components were sandy silt,under the action of internal solitary wave,variation of suspended sediment concentration in layer area was larger than it in slope area.And in the gap of two waves,the duration of higher suspended sediment concentration in slope area was much longer,the maximum could reach 2.5 times of that in the layer area.When the composition of sediment was clayey silt,the increased value of suspended matter concentration in the sediment slope area was 1.6-2.2 times of that in the sediment layer area.