Experimental Study On Flexible Silt Curtain

One of the most severe problems of port construction on silty coast is the deposition of sediment in basins and channels.The problem is common in many ports,and is costly and time-consuming.The silt curtain,composed of a floater,a ballast and a flexible curtain,is a new kind of structure to prevent suspended sediment deposition.It is costeffective and highly efficient in preventing deposition in the channel from suspended sediment.Therefore it is a worthy investigation for application.This dissertation takes the silt curtain as the main research object.The study contents and results are as follows:(1)Physical model experiments were conducted to study the properties of different materials of silt curtain in preventing sediment leakage and their permeability under different waterheads and different sediment concentrations.Based on a newly-designed circulation leakage box system and related measures,the efficiencies of four kinds of curtain materials were investigated in preventing leakage of suspended sediment under the conditions composed of three waterheads,including 40 cm,70cm and 100 cm,and four sediment concentrations.Based on the results of tests,the filament woven fabric is chosen for the following research because of its highest efficiency in preventing sediment leakage.(2)Physical experiments were conducted to study the tension induced in the silt curtain under combined current and waves.A device was newly designed and made for measurement of the tension in the silt curtain.The tension was measured under current and wave-current coexisting conditions along with different water depth,different water level differences,different diameters and different weight of floaters.Comparison was conducted between the experimental data and predicted results by previously-proposed formula.The results show that the theoretical formulas of curtain tension induced by waves need to be improved.(3)Based on analysis of the data,wave period is considered to be the most important factor.Then the related theoretical formulas were improved by means of regression.Comparison between the experimental data and the new numerical solutions show that significant improvement is achieved.