GROWTH AND TRANSFORMATION OF ALTERNATE BARS UNDER SINUSOIDAL WAVE FLOOD CONDITIONS(Engineering)

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Growth and transformation process of alternate bars and variations in flow depth and sediment transport rate under sinusoidal wave flood conditions are investigated on the basis of flume tests using the uniform sediment and the graded sediment. Experimental results show that the transformation process of alternate bars is influenced by the wave period strongly. That is, an effect of the change rate of discharge on the growth and transformation is large in case of a short wave period, whereas it is relatively small in case of a long wave period. The wave height of an individual alternate bar in the graded sediment bed is always lower than that in the uniform one during the flood period. This reason is that the erosion of bed in the pool is restrained by coarsening of sediments caused by grain sorting. The hysteresis loops are identified in the graphs of discharge-wavelength, discharge-wave height, discharge-flow depth and discharge-sediment transport rate. When the wave period becomes long, the hysteresis loop becomes small, and response-lag of alternate bars to the discharge change becomes small. In addition, width of the hysteresis loops of the wavelength and height in the graded sediment bed is smaller than that for the uniform one under the same wave period. This means that response-lag of alternate bars in the graded sediment bed is smaller than that in the uniform one.
舞鶴工業高等専門学校の論文
2003-03-10