Author(s): Charles Hin Joo Bong; Tze Liang Lau; Aminuddin Ab. Ghani
Linked Author(s): Aminuddin Ab. Ghani, Tze Liang Lau
Keywords: Critical velocity; Deposition thickness; Incipient motion; Sediment
Abstract: The current literature on incipient motion are largely for loose boundary channel with unlimited depth of sediment as compares to rigid boundary channel with limited sediment depth. A few existing literature for rigid boundary channel suggested that the incipient motion value is substantially lower than for loose boundary channels for any particle size. Some existing literature also shown that the current available equations for incipient motion in rigid boundary channel became less accurate as the sediment deposition thickness increased. Nevertheless, the understanding on how the deposition thickness could affect the incipient motion of sediment is still lacking in the literature and need further study. The current study highlights the effect of sediment deposition thickness on incipient motion by conducting experimental work in a rigid rectangular flume of 0. 6 m wide. Results revealed that sediment deposits thickness have effect on the incipient motion of the sediment particle at low sediment deposits thickness and the effect will diminished with the increased in thickness of the sediment deposits. It was also observed from the current study that the sediment deposits start to behave like a loose boundary for thickness above 48 mm. A new equation was proposed in the current study to predict critical velocity during incipient motion by incorporating the sediment deposits thickness. This new equation appears to be consistent and was not affected by the sediment deposits thickness and is an attempt toward unifying the equations for both rigid boundary and loose boundary conditions.
Year: 2015