The incipient velocity of sediment is one of the most important basic theoretical problems of hydraulic engineering. The initial motion of sediment is a random process. Based on the combination methods of classical me...The incipient velocity of sediment is one of the most important basic theoretical problems of hydraulic engineering. The initial motion of sediment is a random process. Based on the combination methods of classical mechanics with statistics theory the formula to calculate the incipient motion of sediment was established. According to the standard of incipient motion, motion status, relative degree of expose for sediment and equivalent grain were defined. The coefficient in the formula included the flow fluctuation and relative degree of exposition. The value of the coefficient was calculated by using some parameters value. The results show that the value of dimensionless shear stress coefficient is not a constant, but locating in a range from 0.022 to 0.063 for weak and middle motion status, and varying with the relative degree of sediment expose. The value of dimensionless Shields numbers that put forward in the text can explain the reason that why the coefficients in difference formulas have wide scatter. The theoretical formula has been verified with amount of data collected from both natural rivers and flumes. The results can reflect the motion characteristic of the sediment.展开更多
文摘The incipient velocity of sediment is one of the most important basic theoretical problems of hydraulic engineering. The initial motion of sediment is a random process. Based on the combination methods of classical mechanics with statistics theory the formula to calculate the incipient motion of sediment was established. According to the standard of incipient motion, motion status, relative degree of expose for sediment and equivalent grain were defined. The coefficient in the formula included the flow fluctuation and relative degree of exposition. The value of the coefficient was calculated by using some parameters value. The results show that the value of dimensionless shear stress coefficient is not a constant, but locating in a range from 0.022 to 0.063 for weak and middle motion status, and varying with the relative degree of sediment expose. The value of dimensionless Shields numbers that put forward in the text can explain the reason that why the coefficients in difference formulas have wide scatter. The theoretical formula has been verified with amount of data collected from both natural rivers and flumes. The results can reflect the motion characteristic of the sediment.
