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You are here : eLibrary : IAHR World Congress Proceedings : 32nd Congress - Venice (2007) : THEME A: Engineering and Management of Fresh-water Systems : Critical bed-shear stress and bed deformation of heavy sediment under steady currents and waves
Critical bed-shear stress and bed deformation of heavy sediment under steady currents and waves
Author : Syamsidik , Hisae Ito, and Shin-Ichi Aoki
In order to seek measures to rehabilitate and to maintain stability of coastal/inlet channels morphology, heavy material, i.e. iron slag, was used as alternative sediment objects in this study. Focus of this study is addressed to critical bed-shear stress of the iron slag, Shields parameter, and sediment transport rates. A series of laboratory researches were conducted by applying steady currents and regular waves. During steady currents experiments, a straight flume with an attached adjustable steady currents propagator was used. In regular waves experiments, an 18-meter long wave flume was operated where an amount of material (the iron slag or sand) was placed in a 2m x 0.8m x 0.1m material pit. The iron slag was divided into four groups of grain size. For comparison, five types of natural sand were also investigated. Swart’s wave friction equation was applied to calculate wave friction factor, fw, and the calculation was proceeded to obtain critical bed-shear stress, cτ , and critical Shields parameter, θc, of each material. The observation and measurement were performed using instruments, namely Vectrino ADV, CCD Laser Displacement Sensors, Ultrasonic Displacement meter, and wave gauges. Determination of the material critical conditions under steady currents and regular waves were conducted by observing the material particles movement while the currents or the wave heights were increased gradually within a small value of interval. Results show that the iron slag need a larger bed-shear stress to move its particle compared to sand under steady currents conditions and regular waves. The iron slag’s final bed profiles showed no significant changes compared to their initial profiles in the regular waves experiments. The iron slag’s bed profiles stability is considered as prospects of the iron slag usage for inlet channels/coastal bed stabilizing purposes.
File Size : 210,301 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 32nd Congress - Venice (2007)
Article : THEME A: Engineering and Management of Fresh-water Systems
Date Published : 01/07/2007
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